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MANUAL 


OF   THE 


DISSECTION  OF  THE  HUMAN  BODY 


LUTHER    HOLDEN 


LATE  PRESIDENT  OP  THE  ROYAL  COLLEGE  OP  SURGEONS  OP  ENGLAND 
CONSULTING   SURGEON  TO   ST.  BARTHOLOMEW'S   AND   FOUNDLING    HOSPITALS 


FIFTH  EDITION 

EDITED  BY 

JOHN    LANGTON 

SURGEON  TO,  AND  LECTURER  ON  ANATOMY  AT,  ST.  BARTHOLOMEW'S  HOSPITAL 
MEMBER  OF  THE   BOARD  OF  EXAMINERS,   ROYAL  COLLEGE  OF  SURGEONS  OF  ENGLAND 

SURGEON  TO  THE  CITY  OF  LONDON   TRUSS   SOCIETY 

CONSULTING  SURGEON  TO  THE  CITY  OF  LONDON   LYING-IN  HOSPITAL 
AND  TO  THE  MEMORIAL  HOSPITAL  AT  MILDMAY   PARK 


PHILADELPHIA : 

P.    BLAKISTON,    SON    &    CO., 

1012    WALNUT    STREET. 


TO 

THE    STUDENTS 

OF 

ST   BABTHOLOMEW'S   HOSPITAL 

IN     THE     HOPE     THAT     IT     MAY     ASSIST     THEM     IN     THEIR 
ANATOMICAL     STUDIES 

h  grifoaUfc 

\ 

BY    THBIE   FAITHFUL   FRIEND    AND    WELL-WISHER 

THE   AUTHOR 


>- 


PREFACE 


THE    FIFTH    EDITION. 


IN  THIS  EDITION  the  Editor  has  most  carefully  revised  the  entire 
work.  The  order  of  dissection  has  been  here  and  there  altered, 
and  further  illustrations  and  additional  matter  introduced,  especi- 
ally concerning  the  Anatomy  of  the  Nervous  System  and  the  Organs 
of  Special  Sense. 

The  object  throughout  has  been  to  be  as  concise  as  possible, 
and  to  put  the  subject  in  as  clear  and  practical  a  light  as  is  com- 
patible with  the  faithful  handling  of  its  natural  difficulties. 

It  is  hoped  that  the  work,  in  its  present  form,  is  adapted,  not 
only  for  students,  but  for  members  of  the  profession  who  wish  to 
refresh  their  anatomical  knowledge. 

The  best  thanks  of  the  Editor  are  due  to  the  Demonstrators 
and  Assistant  Demonstrators  of  Anatomy  at  St.  Bartholomew's 
Hospital  for  valuable  suggestions. 


2  HARLEY  STREET,  CAVENDISH  SQUARE  : 
September  1884. 


X  PEEFACE    TO    THE    FIRST    EDITION. 

The  several  regions  of  the  body  are  treated  of  in  the  order 
considered  most  suitable  for  their  examination ;  and  the  muscles, 
vessels,  nerves,  &c.  are  described,  as  they  are  successively  exposed 
to  view  in  the  process  of  dissection. 

The  Author  has  written  the  work  entirely  from  actual  observa- 
tion :  at  the  same  time  no  available  sources  of  information  have 
been  neglected,  the  highest  authorities  both  English  and  Foreign 
having  been  carefully  consulted.  His  acknowledgments  are 
especially  due  to  F.  C.  SKEY,  Esq.  F.R.S.,  Lecturer  on  Anatomy 
at  St.  Bartholomew's  Hospital,  for  many  valuable  suggestions. 
He  is  also  much  indebted  to  his  young  friend,  Mr.  W.  CLUBBE,  for 
able  assistance  in  dissections. 

September  1851. 


CONTENTS. 


PAKE 

DISSECTION  OF  THE  SCALP      .            .            .            .            .  1 

DISSECTION  OF  THE  FACE  .  .  .  .  .  .24 

DISSECTION  OF  THE  ORBIT      .            .            .            .            .  49 

DISSECTION  OF  THE  NECK  .  .  .  .  .  .63 

COURSE  AND  EELATIONS  OF  THE  SUBCLAVIAN  ARTERIES      .                   .  113 

THE  MUSCLES  OF  MASTICATION.     TEMPORAL  AND  PTERYGO-MAXILLARY 

EEGIONS    .            .            .            .            .            .            .            .  127 

BRANCHES  OF  THE  INTERNAL  MAXILLARY  ARTERY  IN  THE  THREE  STAGES 

OF  ITS  COURSE      ........  134 

BRANCHES  OF  THE  INFERIOR  MAXILLARY  NERVE             .            .            .  138 

DISSECTION  OF  THE  THORAX  .            *.  -                     .            .            .  155 

DISSECTION  OF  THE  HEART           ......  198 

FOZTAL  CIRCULATION    .            .            .            .                      '.            .      .  213 

STRUCTURE  OF  THE  LUNGS        '    .  •  •        .            .            .            .            .  216 

DISSECTION  OF  THE  PHARYNX             .            .            .            .            .       .  224 

DISSECTION  OF  THE  LARYNX         ......  238 

DISSECTION  OF  THE  TONGUE  .            .            .            .            .            .  253 

DISSECTION  OF  THE  SUPERIOR  MAXILLARY  NERVE         .            .            .  258 

DISSECTION  OF   THE  NINTH,  TENTH,  AND  ELEVENTH  CRANIAL  NERVES 

AT  THE  BASE  OF  THE  SKULL      .            .            .            .            .       .  265 

DISSECTION  OF  THE  NOSE             ......  271 

DISSECTION  OF  THE  MUSCLES  OF  THE  BACK             .            .            .  278 

LIGAMENTS  OF  THE  SPINE             ......  295 

DISSECTION  OF  THE  UPPER  EXTREMITY         .            .            .            .  305 

DISSECTION  OF  THE  AXILLA  312 


Xll  CONTENTS. 

PAGE 

DISSECTION  OF  THE  UPPEK  ARM        .            .            .            .            .  324 

DISSECTION  OF  THE  FRONT  OF  THE  FOREARM     ....  839 

DISSECTION  OF  THE  PALM  OF  THE  HAND      .            .            .            .  353 

MUSCLES  OF  THE  BACK  CONNECTED  WITH  THE  ARM       .            .            .  366 

DISSECTION  OF  THE  MUSCLES  OF  THE  SHOULDER    .            .            .  378 

DISSECTION  OF  THE  BACK  OF  THE  FOREARM       .....  387 

DISSECTION  OF  THE  LIGAMENTS         .            .            .            .            .  401 

DISSECTION  OF  THE  ABDOMEN       ......  419 

DISSECTION  OF  THE  PARTS  CONCERNED  IN  INGUINAL  HERNIA         .       .  440 

DISSECTION  OF  THE  PELVIC  VISCERA       .....  499 

DISSECTION  OF  THE  MALE  PERINEUM            .            .            .            .  505 

DISSECTION  OF  THE  FEMALE  PERINEUM  .....  521 

ANATOMY  OF  THE  SIDE  VIEW  OF  THE  PELVIC  VISCERA       .            .       .  525 

STRUCTURE  OF  THE  BLADDER,  PROSTATE,  URETHRA,  AND  PENIS           .  547 

DISSECTION  OF  THE  FEMALE  PELVIC  VISCERA          .            .            .  562 

DISSECTION  OF  THE  ABDOMINAL  VISCERA             ....  575 

DISSECTION  OF  THE  LOWER  EXTREMITY        .            .            .            .  609 

ANATOMY  OF  THE  PARTS  CONCERNED  IN  FEMORAL  HERNIA        .            .  619 

DISSECTION  OF  THE  FRONT  OF  THE  LEG       .            .            .            .  643 

DISSECTION  OF  THE  GLUTEAL  EEGION     .            .            .            .            .  653 

DISSECTION  OF  THE  BACK  OF  THE  THIGH      .            .            .            .  668 

DISSECTION  OF  THE  BACK  OF  THE  LEG   .....  672 

DISSECTION  OF  THE  SOLE  OF  THE  FOOT       .            .            .            .       .  683 

DISSECTION  OF  THE  LIGAMENTS    .            .            ,..•'.            .            .  693 

DISSECTION  OF  THE  BRAIN     .            .            .            .            .            .       .  715 

DISSECTION  OF  THE  SPINAL  CORD             .....  780 

DISSECTION  OF  THE  EYE         .            .            .            .            .            .  793 

DISSECTION  OF  THE  ORGAN  OF  HEARING             ....  816 

DISSECTION  OF  THE  MAMMARY  GLAND           .            .            .            .  836 

DISSECTION  OF  THE  SCROTUM  AND  TESTIS           ....  838 

INDEX                                                                                                           ,  849 


LIST    OF    ILLUSTBATIONS. 


1.  Muscular  and  Aponeurotic  Stratum  of  the  Scalp  .             .             .2 

2.  Sensory  Nerves  of  the  Scalp  and  Face       .             .  .             .       .       5 

3.  Branches  of  the  Facial  Nerve   .             .             .  .             .             .7 

4.  Diagram  to  show  the  Formation  of  a  Sinus           .  .                   .     11 

5.  The  Cranial  Sinuses       .             .             .             .  .             .             .11 

6.  The  Venous  Sinuses  at  the  Base  of  the  Skull         .  .                    .     15 

7.  The  Exit  of  the  Cranial  Nerves             .             .  .             .             .18 

8.  The  Nerves  in  the  Foramen  Jugulare        .             .  .             .       .     20 

9.  Relation  of  Structures  in  the  Cavernous  Sinus  .             .             .21 

10.  Eelations  of  the  Nerves  in  the  Sphenoidal  Fissure  .                   .     22 

11.  Eelations  of  the  Nerves  and  Muscles  in  the  Orbit  .             .             .22 

12.  The  Geniculate  Ganglion  of  the  Facial  Nerve        .  .            .       .     28 

13.  The  Muscles  of  the  Face            .            .            .  .             .             .26 

14.  The  Lachrymal  Apparatus              .            .             .  ...     83 

15.  The  Muscles  of  the  Pharynx     .             .             .  '      .     .  .             .37 

16.  The  Branches  of  the  External  Carotid  Artery       .  .                    .     39 

17.  The  Branches  of  the  Facial  Nerve        .             .  .             .             .46 

18.  The  Sensory  Nerves  of  the  Scalp  and  Face            .  .            .      .     48 

19.  The  Nerves  of  the  Orhit            .            .            .  .            .            .50 

20.  View  of  the  Orbit  from  above          .             .             .  .             .       .     52 

21.  Lachrymal  Duct             .             .             .             .  .             .             .54 

22.  View  of  the  Optic  and  Lower  Nerves  of  the  Orbit  .            .      .     57 

23.  Insertion  of  the  Eecti  Muscles              .            .  •            •            .62 

24.  The  Superficial  Nerves  and  Veins  of  the  Neck      .  .            .       .     66 


Xll  CONTENTS. 

PAGE 

DISSECTION  OF  THE  UPPER  ARM        .            .            .            .            .  324 

DISSECTION  OF  THE  FRONT  OF  THE  FOREARM     ....  339 

DISSECTION  OF  THE  PALM  OF  THE  HAND      .            .            .            .       .  353 

MUSCLES  OF  THE  BACK  CONNECTED  WITH  THE  ARM       .            .            .  366 

DISSECTION  OF  THE  MUSCLES  OF  THE  SHOULDER    .            .            .  378 

DISSECTION  OF  THE  BACK  OF  THE  FOREARM       .....  387 

DISSECTION  OF  THE  LIGAMENTS          .            .            .            .            .  401 

DISSECTION  OF  THE  ABDOMEN       ......  419 

DISSECTION  OF  THE  PARTS  CONCERNED  IN  INGUINAL  HERNIA         .       .  440 

DISSECTION  OF  THE  PELVIC  VISCERA       .....  499 

DISSECTION  OF  THE  MALE  PERINEUM            .            .            .            .  505 

DISSECTION  OF  THE  FEMALE  PERINEUM  .....  521 

ANATOMY  OF  THE  SIDE  VIEW  OF  THE  PELVIC  VISCERA       .            .       .  525 

STRUCTURE  OF  THE  BLADDER,  PROSTATE,  URETHRA,  AND  PENIS           .  547 

DISSECTION  OF  THE  FEMALE  PELVIC  VISCERA          .            .            .  562 

DISSECTION  OF  THE  ABDOMINAL  VISCERA             ....  575 

DISSECTION  OF  THE  LOWER  EXTREMITY        .            .            .            .  609 

ANATOMY  OF  THE  PARTS  CONCERNED  IN  FEMORAL  HERNIA        .            .  619 

DISSECTION  OF  THE  FRONT  OF  THE  LEG       .            .            .            .  643 

DISSECTION  OF  THE  GLUTEAL  EEGION     .....  653 

DISSECTION  OF  THE  BACK  OF  THE  THIGH      .            .            .            .  668 

DISSECTION  OF  THE  BACK  OF  THE  LEG   .....  672 

DISSECTION  OF  THE  SOLE  OF  THE  FOOT       .            .            .            .       .  683 

DISSECTION  OF  THE  LIGAMENTS    .            .            .            .            .            .  693 

DISSECTION  OF  THE  BRAIN     .            .            .            .            .            .       .  715 

DISSECTION  OF  THE  SPINAL  CORD             .....  780 

DISSECTION  OF  THE  EYE         .            .            .            .            .            .  793 

DISSECTION  OF  THE  ORGAN  OF  HEARING              ....  816 

DISSECTION  OF  THE  MAMMARY  GLAND           .            .            .            .  836 

DISSECTION  OF  THE  SCROTUM  AND  TESTIS           ....  838 

V 

INDEX                                                                                                         ,  849 


LIST    OF    IKLUSTKATIONS. 


FIG.  PAGE 

1.  Muscular  and  Aponeurotic  Stratum  of  the  Scalp  .             .             .2 

2.  Sensory  Nerves  of  the  Scalp  and  Face       .             .  .                           5 

3.  Branches  of  the  Facial  Nerve   .             .             .  .             .             .7 

4.  Diagram  to  show  the  Formation  of  a  Sinus           .  .                   .     11 

5.  The  Cranial  Sinuses       .             .             .             .  .             .             .11 

6.  The  Venous  Sinuses  at  the  Base  of  the  Skull        .  .                   .     15 

7.  The  Exit  of  the  Cranial  Nerves             .            .  .            .            .18 

8.  The  Nerves  in  the  Foramen  Jugulare        .             .  .             .       .     20 

9.  Relation  of  Structures  in  the  Cavernous  Sinus  .             .             .21 

10.  Relations  of  the  Nerves  in  the  Sphenoidal  Fissure  .                   .     22 

11.  Relations  of  the  Nerves  and  Muscles  in  the  Orbit  .             .             .22 

12.  The  Geniculate  Ganglion  of  the  Facial  Nerve        .  .            .       .     23 

13.  The  Muscles  of  the  Face            .            .             .  .             .             .26 

14.  The  Lachrymal  Apparatus              .             .             .  ...     33 

15.  The  Muscles  of  the  Pharynx     .             .             .  '     .    .  .             .37 

16.  The  Branches  of  the  External  Carotid  Artery       .  .                    .     39 

17.  The  Branches  of  the  Facial  Nerve        .             .  .             .             .46 

18.  The  Sensory  Nerves  of  the  Scalp  and  Face            .  .            .       .     48 

19.  The  Nerves  of  the  Orbit            .            .            .  .            .            .50 

20.  View  of  the  Orbit  from  above          .             .             .  .             .       .     52 

21.  Lachrymal  Duct             .             .             .             .  .             .             .54 

22.  View  of  the  Optic  and  Lower  Nerves  of  the  Orbit  .             .       .     57 

23.  Insertion  of  the  Recti  Muscles              .            .  .            .            .62 

24.  The  Superficial  Nerves  and  Veins  of  the  Neck      .  .            .      .     66 


xiv  LIST   OF   ILLUSTRATIONS. 

F[G.  PAGE 

25.  The  Triangles  of  the  Neck             .             .             .             .  73 

26.  Central  Line  of  the  Neck         ......  78 

27.  Digastric  Triangle  and  Contents  .             .             .             .  92 

28.  The  Branches  of  the  External  Carotid  Artery  and  their  Branches    .  97 

29.  Muscles,  Vessels,  and  Nerves  of  the  Tongue        .             .             .       .  102 

30.  The  Heart  and  Large  Vessels              .....  114 

31.  The  Inosculations  of  the  Subclavian  Artery        .             .             .  122 

32.  The  Formation  of  the  Brachial  Plexus  and  its  Branches       .             .  125 

33.  Pterygoid  Muscles  and  the  Internal  Maxillary  Artery    .             .       .  132 

34.  Plan  of  the  Internal  Maxillary  Artery            ....  135 

35.  Plan  of  the  Branches  of  the  Inferior  Maxillary  Nerve    .             .       .  139 

36.  The  Communications  of  the  Facial,  Glosso-pharyngeal,  Pneumo- 

gastric,  Spinal  Accessory,  Hypoglossal,  Sympathetic,  and  the  two 

Upper  Cervical  Nerves          ......  152 

37.  Form  and  Position  of  the  Lungs  .             .             .             .             .  156 

38.  The  Reflections  of  the  Pleural  Sacs    .....  161 

39.  The  Heart,  showing  Interpleural  Space    .             .             .             .  163 

40.  Form  and  Position  of  the  Lungs         .....  164 

41.  Eelative  Position  of  the  Heart  and  its  Valves  with  regard  to  the 

Walls  of  the  Chest          .            .            .            .            .            .       .  168 

42.  Superior  Vena  Cava  and  its  Tributaries         .            .             .  173 

43.  Course  and  Eelations  of  the  Arch  of  the  Aorta    .             .             .  175 

44.  The  Course  of  the  Vena  Azygos  and  the  Thoracic  Duct         .             .  183 

45.  The  Thoracic  Portion  of  the  Sympathetic  Nerve             .             .       .  189 

46.  Diagram  of  a  Spinal  Nerve      ......  192 

47.  The  Constituents  of  the  Boot  of  each  Lung  and  their  relative  position  197 

48.  The  Interior  of  the  Bight  Auricle             .             .             .             .  201 

49.  The  relative  Position  of  the  Valves  of  the  Heart  seen  from  above    .  209 

50.  Scheme  of  the  Festal  Circulation              .             .             .             .       .  214 

51.  Ultimate  Air-cells  of  the  Lung            .....  222 

52.  Side  view  of  the  Muscles  of  the  Pharynx             .             .             .  227 

53.  View  of  the  Constrictor  Muscles  from  behind             .             .             .  229 

54.  View  of  the  Pharynx  laid  open  from  behind        .             .             .  231 

55.  Shape  of  the  Glottis  when  at  rest       .....  246 

56.  Diagram  showing  the  Action  of  the  Crico-thyroid  Muscle           .       .  247 


LIST   OF  ILLUSTRATIONS.  XV 

FIG.  PAGE. 

57.  Glottis  dilated  :  Muscles  dilating  it     .             .             .             .             .  248 

58.  Side  view  of  the  Muscles  of  the  Larynx  .             .             .             .       .  249 

59.  Glottis  closed :  Muscles  closing  it                    .             .             .             .  250 

60.  Upper  Surface  of  the  Tongue,  with  the  Fauces  and  Tonsils        . ,     .  254 

61.  Diagram  of  the  Superior  Maxillary  Nerve .                  «•  259 

62.  Deep  view  of  the  Spheno -palatine  Ganglion         .             .             .  261 

63.  Communications  of  the  Facial,  Glosso-pharyngeal,  Pneumogastric, 

Spinal  Accessory,  Hypoglossal,  Sympathetic,  and  the  two  Upper 

Cervical  Nerves         .......  264 

64.  The  Geniculate  Ganglion  of  the  Facial  Nerve  and  its  Communica- 

tions       .             .             .             .             .             .             .                    .  268 

65.  Cartilages  of  the  Nose .  .  .  .  .  •  .272 

66.  Transverse  Section  through  the  Abdomen  to  show  the  attachment  of 

the  Lumbar  Fascia         .             .             .             .             .             .  279 

67.  The  Superficial  Muscles  of  the  Back  .  .  .  .  .280 

68.  The  Suboccipital  Triangle             .             .             .             .                    .  288 

69.  The  Cutaneous  Nerves  of  the  Back    .....  292 

70.  The  Prevertebral  Muscles  .  .  .  .  ... 

71.  The  Odontoid  and  Transverse  Ligaments       .... 

72.  Costo-vertebral  Ligaments  .  .  .  .  . 

73.  The  Ligaments  connecting  the  Eib  with  the  Vertebra 

74.  Transverse  Section  to  show  the  Ligaments  and  the  Fibro-Cartilage 

of  the  Lower  Jaw           .            .            .            .            .            .      .  304 

75.  The  Axilla        ........  316 

76.  Plan  of  the  Branches  of  the  Axillary  Artery        .             .             .  317 

77.  The  Origins  of  the  Triceps       .  .  .  .  .  .318 

78.  The  Brachial  Plexus  of  Nerves     .             .             .             .                    .  320 

79.  Distribution  of  the  Cutaneous  Nerves  to  the  front  of  the  Shoulder 

and  Arm         ........  325 

80.  Superficial  Veins  and  Nerves  at  the  bend  of  the  Left  Elbow      .       .  326 

81.  Plan  of  the  Chief  Branches  of  the  Brachial  Artery    .             .             .  334 

82.  The  Muscles  of  the  Front  of  the  Forearm            .             .             .       .  343 

83.  The  Superficial  and  Deep  Palmar  Arches       .             .             .  356 

84.  Cutaneous  Nerves  of  the  Back      .             .             .             .             .  369 

85.  The  Superficial  Muscles  of  the  Back  .  .  .  .  .371 


Xvi  LIST    OF   ILLUSTRATIONS. 

FIG.  PAGE 

86.  Cutaneous  Nerves  of  the  Left  Shoulder  and  Arm  (posterior  view)  .  378 

87.  Analysis  of  the  Deltoid          .  .  .  .  .  .380 

88.  The  Arteries  of  the  Scapula         .             .             .             .            .  384 

89.  The  Anastomoses  of  the  Arteries  at  the  back  of  the  Elbow  and  Wrist 

Joints  .  .  .  .  .  .  .  .396 

90.  The  Dorsal  Interossei      .             .            .             .            .             .       .  399 

91.  The  Palmar  Interossei,  and  the  Adductor  Pollicis    .             .             .  399 

92.  The  Sterno- clavicular  Ligaments            .             .            .             .       .  402 

93.  Anterior  view  of  the  Scapulo-clavicular  Ligaments,   and  of  the 

Shoulder-joint        .......  404 

94.  Ligaments  of  the  Elbow-joint     .             .             .             .             .  408 

95.  The  Ligaments  and  Synovial  Membranes  of  the  Wrist-joint           .  412 

96.  The  Abdominal  Eegions .             .             .             .             .             .  420 

97.  Superficial  Vessels  and  Glands  of  the  Groin              .             .             .  422 

98.  Poupart's  Ligament,  and  the  External  Abdominal  Ring            .       .  426 

99.  The  Lower  Fibres  of  the  Internal  Oblique  and  Transversalis,  with 

the  Cremaster  Muscle         ......  428 

100.  Transverse  Section  to  show  the  Formation  of  the  Sheaths  of  the 

Eectus,  the  Quadratus  Lumborum,  and  the  Erector  Spinae   .       .  431 

101.  The  Fascia  Transversalis  seen  from  the  front           .             .             .  435 

102.  Varieties  of  Congenital  Inguinal  Herniae            .             .             .       .  444 

103.  Section  to  show  the  Ileo-caecal  Valve  and  Appendix  Vermiformis  .  451 

104.  Relative  Position  of  the  Kidneys  and  the  Large  Intestine,  seen  from 

behind   .            .            .             .            .             .             .                    .  452 

105.  The  Peritoneum          .......  459 

106.  A  Transverse  Section  through  the  Upper  Part  of  the  Abdominal 

Cavity    .             .             .            .             .             .             .                   .  461 

107.  A  Transverse  Section  through  the  Lower  Part  of  the  Abdominal 

Cavity           ........  461 

108.  Branches  of  the  Abdominal  Aorta           .             .            .             .  465 

109.  The  Branches  of  the  Coeliac  Axis       .....  467 

110.  The  Vena  Portse  .             .            .             .             .             .                    .  470 

111.  Plan  of  the  Mesenteric  Arteries,  and  their  Communications             .  471 

112.  The  Diaphragm   .             .             .             .             .            .                   .  478 

113.  The  Diaphragm  from  its  Upper  Surface       ....  479 


LIST    OF   ILLUSTRATIONS. 

FIG.  PAGE 

114.  The  Course  and  Kelations  of  the  Abdominal  Aorta  and  Vena  Cava 

Inferior.             ........  483 

115.  Plan  of  the  Lumbar  Plexus  and  Branches    ....  497 

116.  The  Relative  Position  of  the  Pelvic  Viscera       .             .             .       .  502 

117.  Vertical  Section  through  the  Female  Pelvic  Viscera            .             .  504 

118.  Framework  of  the  Perineum       .            .             .             .             .  505 

119.  Muscles,  with  Superficial  Vessels  and  Nerves,  of  the  Perineum      .  510 

120.  The  Accelerator  Urinae  in  profile             .             .             .             .  512 

121.  The  Triangular  Ligament  of  the  Urethra     ....  513 

122.  The  Parts  behind  the  Anterior  Layer  of  the  Triangular  Ligament .  514 

123.  The  Relations  of  the  Compressor  Urethras    ....  518 

124.  Bulb  of  the  Vagina           .             .             .             .             .             .       .  524 

125.  Vertical  Section  through  the  Perineum  and  Pelvic  Viscera             .  526 

126.  Transverse  Section  to  show  the  Reflections  of  the  Pelvic  Fascia     .  527 

127.  Side  View  of  the  Pelvic  Viscera         .  .  .  .  .530 

128.  Posterior  View  of  the  Bladder     .             .             .             .                    .  533 

129.  Plan  of  the  Branches  of  the  Internal  Iliac  Artery    .             .             .  539 

130.  View  of  the  Abnormalities  of  the  Obturator  Artery        .             .       .  541 

131.  Plan  of  the  Sacral  Plexus  and  Branches       ....  545 

132.  Bladder  and  Urethra  exposed  from  the  Upper  Surface              .       .  549 

133.  Transverse  Sections  of  the  Urethra  .....  556 

134.  Transverse  Section  through  the  Penis    .             .             .             .       .  560 

135.  The  Uterus,  the  Ovaries,  and  Fallopian  Tubes         .            .             .  571 

136.  The  Under  Surface  of  the  Liver .             .             .             .                    .  5177 

137.  Transverse  Sections  of  Lobules  of  the  Liver                                       .  579 

138.  Longitudinal  Sections  of  Lobules  of  the  Liver  .                          .       .  580 

139.  Section  of  the  Kidney  .  .  .  .  .  .590 

140.  The  Course  and  Arrangement  of  the  Uriniferous  Tubes             .       .  592 

141.  A  Tubulus  Uriniferus  .  .  .  .  .  .594 

142.  Section  to  show  the  Ileo-caecal  Valve     .                          ...  605 

143.  Saphenous  Opening  with  the  Cribriform  Fascia       .             .             .  612 

144.  Fascia  on  the  Outside  of  the  Thigh         .             .             .                    .  616 

145.  The  Femoral  Ring  and  the  Saphenous  Opening       .             .             •  617 

146.  Position  of  Parts  under  the  Crural  Arch                                              •  621 

a 


XV111  LIST    OF   ILLUSTRATIONS. 

FIG.  PAGE 

147.  The  Sheath  of  the  Femoral  Vessels  .  .  .  .  .622 

148.  View  of  the  Abnormalities  of  the  Obturator  Artery        .             .       .  625 

149.  Scarpa's  Triangle        .  .  .  .  .  .  .628 

150.  Section  through  Hunter's  Canal             .             .             .             .       .  637 

151.  Plan  of  the  Inosculations  of  the  Circumflex  Arteries            .             .  640 

152.  Plan  of  the  Sacral  Plexus  and  Branches             .             .             .  660 

153.  Deep  Muscles  of  the  Gluteal  Region              ....  661 

154.  The  Arteries  of  the  Gluteal  Region         .             .             .                    .  663 

155.  Left  Popliteal  Space  .  .  .  .  .  .  .666 

156.  Diagram  showing  Action  of  the  Hamstring  Muscles     .             .       .  671 

157.  Diagram  showing  Action  of  the  Gastrocnemius        .             .             .  676 

158.  Muscles,  Vessels,  and  Nerves  of  the  Sole  of  the  Right  Foot      .       .  686 

159.  Plantar  Arteries          ...  .  .  .  .  .688 

160.  View  of  the  Third  Layer  of  the  Muscles  of  the  Foot      .             .       .  691 

161.  The  Sacro-sciatic  Ligaments  ......  695 

162.  Vertical  Section  through  the  Hip            .             .            .                    .  698 

163.  The  Semilunar  Cartilages  and  Lateral  Ligaments  of  the  Knee        .  702 

164.  Crucial  Ligaments  of  the  Knee  .             .             .             .             .  706 

165.  Ligaments  of  Ankle-joint       ......  708 

166.  The  External  Lateral  Ligament              .             .            .                    .  708 

167.  Calcaneo-cuboid  Articulation             .....  711 

168.  Interosseous  Ligaments  of  the  Cuneiform  Bones           .                   .  712 

169.  The  Articulations  of  the  Tarsus  and  the  Tar  so -metatarsus  .             .  713 

170.  The  Base  of  the  Brain     .             .             .            .            .             .       .  718 

171.  The  Front  Surface  of  the  Medulla  Oblongata  .  .  .723 

172.  The  Fourth  Ventricle  and  the  Restiform  Bodies            .             .       .  725 

173.  The  Course  of  the  Fibres  through  the  Medulla  Oblongata  .             .  728 

174.  The  General  Division  of  the  Brain         .             .             .             .  733 

175.  Convolutions  and  Fissures  of  the  External  Surface  of  the  Brain     .  735 

176.  Convolutions  of  the  Upper  Surface  of  the  Brain            .             .       .  736 

177.  Convolutions  of  the  Base  of  the  Cerebrum    ....  739 

178.  Convolutions  and  Fissures  of  the  Median  Surface  of  Right  Hemi- 

sphere      .             .             .             .             .             .             .             .  741 

179.  Diagram  of  the  Course  of  the  Fibres  through  the  Medulla  and  Pons  746 


LIST   OF  ILLUSTRATIONS.  xix 

FIG.  PAGB 

180.  The  Origins  of  the  Olfactory  and  Optic  Nerves         .  .  .     747 

181.  The  Floor  of  the  Fourth  Ventricle          .  .  .  .     751 

182.  Upper  Surface  of  the  Corpus  Callosum         ....     754 

183.  Diagram  of  the  Lamina  Cinerea  .  .  .  .  754 

184.  Vertical  Section  through  the  Corpus  Callosum,  and  parts  below     .     755 

185.  The  Lateral  Ventricles    .  .  .  .  .  .       .     757 

186.  Transverse  Vertical  Section  through  the  Brain        .  .  .     758 

187.  The  Fornix          .  .  .  .  .  .  .       .     760 

188.  The  Lateral  Ventricles  and  the  Velum  Interpositum  .  .     763 

189.  The  Cerebellum  .  .  .  .  .  .  .       .     768 

190.  Floor  of  the  Fourth  Ventricle  .  .  .  .  .772 

191.  Superior  Surface  of  the  Cerebellum        .  .  .  .       .     775 

192.  Inferior  Surface  of  the  Cerebellum   .  .  .  .  .     777 

193.  The  Spinal  Veins  (vertical  section)         .  .  .  .  781 

194.  The  Spinal  Veins  (transverse  section)  ....     782 

195.  The  Ligamentum  Denticulatum  .  .  .  .  785 

196.  A  Transverse  Section  through  the  Spinal  Cord  and  its  Membranes     787 

197.  Insertion  of  the  Eecti  Muscles   .  .  .  .  .       .     796 

198.  A  Vertical  Section  of  the  Eye  .  .  .  .  .797 

199.  The  Choroid,  the  Ciliary  Muscle,  and  Nerves    .  .  .       .     801 

200.  The  Various  Layers  of  the  Ketina     .....     808 

201.  Arteries  of  the  Eetina     .  .  .  .  .  .  813 

202.  The  Ossicles  of  the  Eight  Tympanum  .  .  .  .822 

203.  Osseous  Labyrinth  of  the  Eight  Side      .  .  .  .  _    .     825 

204.  The  Osseous  Cochlea  .  .  .  .  .  .827 

205.  Section  of  a  Coil  of  the  Cochlea  .  .    •  .  .       .     829 

206.  Vertical  Section  of  the  First  Turn  of  the  Cochlea    .  .  .831 

207.  A  Vertical  Section  through  the  Testicle  .  ...    840 

208.  Transverse  Section  through  the  Left  Testicle  .  .  .    842 


• 


A     MANUAL 

OF    THE 

DISSECTION   OF  THE   HUMAN   BODY. 

DISSECTION   OF  THE   SCALP. 

AN  INCISION  should  be  made  from  the  root  of  the 
nose  along  the  mesial  line  of  the  vertex  to  the 
external  protuberance  of  the  occipital  bone  ;  another,  horizontally 
round  each  half  of  the  head,  to  join  at  right  angles  the  two  ends 
of  the  first  incision.  These  incisions  must  not  divide  more  than  the 
skin,  so  that  the  subcutaneous  vessels  and  nerves  be  not  injured. 
It  is  well  to  dissect  on  one  side  of  the  head  the  muscles  only,  re- 
serving the  other  side  for  the  dissection  of  the  vessels  and  nerves. 

STRATA  COMPOS-  The  several  strata  of  tissues  covering  the  skull- 
ING  THE  SCALP.  cap  are— 1,  the  skin ;  2,  a  thin  layer  of  connective 
tissue  and  fat  which  contains  the  cutaneous  vessels  and  nerves  and 
the  bulbs  of  the  hair ;  and  by  which  the  skin  is  very  closely,  con- 
nected to,  3,  the  broad  thin  aponeurosis  of  the  occipito-frontalis 
muscle  (aponeurosis  of  the  scalp)  ;  4,  an  abundance  of  loose  connec- 
tive tissue,  which  permits  the  free  motion  of  the  scalp  upon,  5,  the 
pericranium,  or  periosteum  of  the  skull-cap. 

Immediately  beneath  the  skin,  then,  we  expose  the  thin  stratum 
of  connective  and  adipose  tissue  which  firmly  connects  it  with  the 
aponeurosis  of  the  scalp.  This  layer  is  continuous  behind  with  the 
superficial  fascia  covering  the  muscles  at  the  back  of  the  neck,  and 
laterally  it  passes  over  the  temporal  fascia.  It  forms  a  bed  for  the 
bulbs  of  the  hair  and  for  the  ramifications  of  the  cutaneous  arteries. 

B 


2  DISSECTION   OF   THE   SCALP. 

The  toughness  of  this  tissue,  in  which  the  arteries  ramify,  does  not 
permit  them  to  retract  when  divided ;  hence  the  haemorrhage  which 
follows  incised  wounds  of  the  scalp ;  hence,  also,  the  difficulty  of 
drawing  them  out  with  the  forceps. 

OCCIPITO-FBON-  This  cutaneous  muscle  is  closely  connected  to 

TALIS  MUSCLE  AND  the  scalp.  It  consists  of  two  fleshy  portions,  one 
EPICBANIAL  On  the  occiput,  the  other  on  the  forehead,  con- 

APONEUBOSIS.  nected   by   a   broad   aponeurosis.      The  occipital 

portion  of  the  muscle  is  thin,  and  takes  origin  from  the  outer  two- 

FIG.  l. 


DIAGBAM   SHOWING    THE    MUSCULAR   AND   APONEUBOTIC    STBATUM   OF   THE   SCALP. 

A.  Attollens  aurem.  c.  Retrahens  aurem. 

B.  Attrahens  aurem.  D.  Orbicularis  palpebrarum. 

thirds  of  the  upper  curved  line  of  the  occipital  bone,  and  the 
adjoining  part  of  the  mastoid  process  of  the  temporal  bone.  The 
fibres  ascend  over  the  back  of  the  head  for  about  two  inches,  and 
then  terminate  in  the  epicranial  aponeurosis.  The  frontal  portion, 
commencing  in  an  arched  form  from  the  epicranial  aponeurosis 
below  the  coronal  suture,  descends  over  the  forehead,  and  termi- 


MUSCLES   OF   THE   PINNA.  3 

nates  partly  in  the  skin  of  the  brow,  partly  in  the  orbicularis  oculi 
and  corrugator  supercilii,  while  some  of  the  inner  fibres  are  con- 
tinuous in  front  of  the  nose  with  the  pyramidalis  nasi  muscle.  The 
aponeurosis  of  the  scalp  covers  the  vertex  of  the  skull,  the  two 
being  continuous  across  the  middle  line.  It  is  continued  over  the 
temples  and  side  of  the  head,  gradually  changing  from  tendinous 
into  connective  tissue.  This  muscle  enables  us  to  move  the  scalp 
backwards  and  forwards.  But  its  chief  action  is  as  a  muscle  of 
expression.  It  elevates  the  brows,  and  occasions  the  transverse 
wrinkles  in  the  expression  of  surprise.  The  occipital  portion  is 
supplied  by  the  posterior  auricular  branch  of  the  facial ;  the  frontal 
portion  by  the  temporal  branch  of  the  same  nerve. 

MUSCLES  OP  THE         There  are  several  small  muscles  to  move  the 
EAE.  cartilage  of  the  ear.     In  man  they  are  thin  and 

pale,  and  require  care  to  dissect  them  out  satisfactorily.  In  animals 
who  possess  a  more  delicate  sense  of  hearing,  they  are  much  more 
developed,  for  the  purpose  of  quickly  directing  the  cartilage  of  the 
ear  towards  the  direction  of  the  sound. 

ATTOLLENS  To   indicate   the    position  of  this   muscle  the 

AUKEM.  student  should  draw  down  the  upper  part  of  the 

pinna  of  the  ear,  when  it  will  be  found  immediately  under  the  ridge 
of  skin  so  produced.  It  is  a  thin  fan-shaped  muscle  and  arises 
from  the  epicranial  aponeurosis,  and  is  inserted  into  the  cranial 
aspect  of  the  upper  part  of  the  concha. 

ATTRAHENS  This  muscle  is  the  smallest  of  these  muscles, 

AUKEM.  and  its  situation  is  indicated  by  the  prominence 

of  skin  produced  by  drawing  backwards  the  front  part  of  the  helix. 
It  arises  from  the  aponeurosis  of  the  occipito-frontalis,  and  is 
inserted  into  the  front  of  the  helix. 

BETRAHENS  This  muscle  is  exposed  by  reflecting  the  skin 

AUKEM.  from  the  ridge  produced  by  drawing  the  pinna 

forwards.  Consisting  of  two  or  three  fasciculi,  it  arises  from  the 
base  of  the  mastoid  process  and  is  inserted  into  the  lower  part  of 
the  concha. 

The  retrahens  and  the  attollens  aurem  are  supplied  by  the  pos- 
terior auricular  branch  of  the  facial  nerve ;  the  attrahens,  by  an 
offset  from  the  temporal  branch  of  the  same  nerve. 

B   2 


4  ARTERIES   OF  THE   SCALP. 

AKTEKIES  OF  The  arteries  of  the  scalp  are  derived,  in  front, 

SCALP.  from  the  supra-orbital  and  frontal  arteries,  branches 

of  the  ophthalmic  artery  which  is  a  branch  of  the  internal  carotid ; 
on  the  sides,  from  the  temporal;  behind,  from  the  occipital  and 
posterior  auricular,  all  branches  of  the  external  carotid. 

The  frontal  emerges  from  the  orbit  at  its  inner  angle  ;  it  runs  up- 
wards for  a  short  distance  on  the  forehead  and  inosculates  with  the 
following  artery. 

The  supra-orbital  passes  through  the  supra-orbital  notch  and  then 
divides  into  a  superficial  and  a  deep  branch.  It  distributes  branches, 
some  of  which  ascend  towards  the  top  of  the  head  and  communicate 
with  the  temporal  and  frontal  arteries. 

The  temporal,  about  two  inches  above  the  zygoma,  divides  into  two 
branches — an  anterior  and  a  posterior.  The  anterior  runs  forwards  in 
a  tortuous  course  and  anastomoses  with  the  supra-orbital  and  frontal 
arteries  ;  the  posterior  (usually  the  larger)  arches  backwards  over  the 
temporal  fascia,  and  its  branches  communicate  with  the  corresponding 
branch  of  the  opposite  side  and  with  the  occipital  and  posterior  auri- 
cular arteries. 

The  posterior  auricidar  is  a  small  vessel  seen  in  the  cleft  between  the 
ear  and  the  mastoid  process.  It  ascends,  and  divides  into  two  branches  : 
one,  the  mastoid  or  occipital,  which  passes  backwards  and  inoscu- 
lates with  the  occipital ;  the  other,  the  auricular,  which  runs  forwards 
above  the  ear  and  communicates  with  the  posterior  branch  of  the 
temporal  artery. 

The  occipital  may  be  noticed  piercing  the  trapezius  near  to  the 
external  occipital  protuberance  ;  ascending  over  the  back  of  the  head, 
it  divides  into  numerous  branches  which  inosculate  with  the  preceding 
arteries. 

The  frontal  vein  passes  downwards  with  its  corresponding  artery, 
and  joins  the  supra-orbital  vein,  to  form  the  angular  vein.  The 
other  veins  of  the  scalp  accompany  their  respective  arteries. 

NERVES  OF  THE          The  sensory  nerves  of  the  scalp  are  derived  from 
SCALP.  each   of  the  three   divisions  of  the  fifth   cranial 

nerve,  namely,  the  ophthalmic,  the  superior  and  inferior  maxillary ; 
also  from  the  second  cervical  nerve.  The  nerves  to  the  muscles  of 
the  scalp  and  ear  come  from  the  facial,  which  is  one  of  the  divisions 
of  the  seventh  cranial  nerve. 


SENSORY  NERVES  OF  THE  SCALP. 


In  front  will  be  found  the  supra-trochlear  and  supra-orbital 
nerves ;  in  the  temporal  region,  there  are  the  temporal  filament 
from  the  orbital  branch  of  the  superior  maxillary,  the  auriculo- 
temporal,  and  the  temporal  branches  of  the  facial  nerve ;  and  behind 
will  be  seen  the  posterior  auricular  branch  of  the  facial,  the  small 
and  great  occipital  nerves,  and  occasionally,  a  small  filament  from 
the  posterior  division  of  the  sub-occipital  nerve. 

FIG.  2. 


DIAGRAM   OF   THE    SENSORY   NERVES   OF   THE    SCALP   AND    FACE.  ,  I 

1.  Great  occipital.   %,  _i,'/u  CiA/wc-0-X.  g.  Supra-trochlear.  J  •>'' 

2.  Small  occipital.  >o  *AW*-          , .  9.  Malar  br.  of  superior  maxillary  nerve. 

3.  Auricular  br.  of  thejmeumogastric.  10.  Infra-trochlear.  /lv  «-^  » 

4.  Great  auricular.  ^poK^C    £i/wH»C.<ILA—          H-  Naso-lobular.     u'vtt'  « 

6.  Temporal  br.  of  superior' maxillary  nerve.       13.  Buccal  br.  of  inferior  maxillary  nerve. 

7.  Supra-orbital,  (t  >J«£.^  •- iijv  fj  5*  14.  Mental.  -•'  ^J     ,,-. 

The  supra-trochlear  nerve  is  derived  from  the  frontal  branch  of  the 
ophthalmic  division  of  the  fifth.  It  appears  at  the  inner  angle  of  the 
orbit,  and  ascending  beneath  the  orbicularis  palpebrarum  and  occipito- 
frontalis,  it  finally  supplies  the  skin  of  the  forehead,  and  the  upper 
eyelid. 

The  supra-orbital  nerve  is  a  continuation  of  the  frontal  branch  of 
the  fifth.  It  emerges  from  the  orbit  through  the  notch  in  the  frontal 


6  NERVES   OF   THE   SCALP. 

bone,  and  subdivides  into  branches,  which  are  covered  at  first  by  the 
fibres  of  the  orbicularis  and  occipito-frontalis ;  but  they  presently 
become  subcutaneous,  and  terminate  in  two  branches — an  inner,  which 
ascends,  to  supply  the  structures  as  high  as  the  parietal  bone  ;  and  an 
otiter  and  larger,  which  may  be  traced  over  the  vertex  as  far  as  the 
occipital  bone. 

The  temporal  branch  of  the  orbital  branch  of  the  superior  maxillary 
nerve  pierces  the  temporal  fascia  about  an  inch  above  the  zygoma,  and 
is  distributed  to  the  skin  of  the  temple,  communicating  with  the  facial 
nerve  and  occasionally  with  the  following. 

The  auriculo-temporal  nerve,  a  branch  of  the  inferior  maxillary 
nerve,  after  sending  a  small  filament  to  the  upper  part  of  the  pinna, 
divides  into  two  branches,  which  accompany  the  divisions  of  the  super- 
ficial temporal  artery ;  of  these,  the  posterior  is  the  smaller.  The 
anterior  communicates  with  the  facial  nerve,  and  with  the  orbital 
branch  of  the  superior  maxillary. 

The  temporal  branches  of  the  facial  nerve  lie  superficial  to  the 
temporal  fascia,  and  supply  the  attrahens  and  attollens  aurem,  the  orbi- 
cularis palpebrarum,  the  corrugator  supercilii  and  the  occipito-frontalis. 
These  branches  communicate  with  the  temporal  branch  of  the  superior 
maxillary,  the  auriculo-temporal  nerve,  and  with  the  lachrymal  and 
supra- orbital  branches  of  the  ophthalmic. 

The  posterior  atirictdar  nerve  is  a  branch  of  the  facial,  and  divides 
like  its  accompanying  artery  behind  the  pinna  of  the  ear  into  a  pos- 
terior or  occipital  branch  which  supplies  the  posterior  belly  of  the 
occipito-frontalis,  and  into  an  anterior  or  aurlctdar  branch  which  ends 
in  the  auricle,  the  retrahens  and  attollens  aurem.  It  communicates 
with  the  great  auricular  and  small  occipital  nerves,  and  with  the 
auricular  branch  (Arnold's)  of  the  pneumogastric. 

The  auricular  branch  of  the  pneumogastric  (Arnold's)  emerges  from 
the  auricular  fissure  immediately  behind  the  pinna,  and  supplies  the 
skin  of  the  pinna  and  the  neighbourhood. 

The  great  occipital  nerve  is  the  internal  branch  of  the  posterior 
division  of  the  second  cervical  nerve.  After  piercing  the  complexus  it 
appears  on  the  occiput  with  the  occipital  artery,  and  divides  into  wide- 
spreading  branches  which  supply  the  skin.  It  communicates  with  the 
posterior  auricular,  the  small  occipital,  and  the  third  cervical  nerves. 

The  small  occipital  nerve,  a  branch  of  the  anterior  division  of  the 
second  cervical  nerve,  runs  along  the  posterior  border  of  the  sterno- 
mastoid  and  supplies  the  scalp  behind  the  ear.  It  communicates  with 
the  great  auricular,  and  with  the  two  preceding  nerves. 


NERVES   OF  THE   SCALP.  7 

Occasionally,  though  rarely,  a  cutaneous  branch  of  the  suboccipital 
nerve  is  distributed  to  the  back  of  the  head. 

FIG.  3. 


DIAGBAJI   OF   THE   BRANCHES   OF   THE   FACIAL   NEEVE. 


1.  Branch  to  occipito-frontalis. 

2.  Posterior  auricular. 

3.  Temporal  brs. 

4.  Malar  brs. 


5.  Infra-orbital. 

6.  Buccal. 

7.  Supra-maxillary. 

8.  Infra-maxillary. 


POINTS  OF  SUB-  Raise  the  aponeurosis  of  the  scalp,  and  observe 
GICAL  INTEREST.  the  quantity  of  loose  connective  tissue  which 
intervenes  between  it  and  the  pericranium.  This  tissue  never 
contains  fat.  There  are  some  points  of  surgical  interest  concern- 
ing it : — 1.  Its  looseness  accounts  for  the  extensive  effusions  of 
blood  which  one  often  sees  after  injuries  of  the  head.  2.  It 
admits  of  large  flaps  of  the  scalp  being  detached  from  the  skull- 
cap ;  but  these  flaps  rarely  slough,  unless  severely  damaged, 
because  they  carry  their  blood-vessels  with  them.  3.  In  phleg- 
monous  erysipelas  of  the  scalp,  the  connective  tissue  becomes 
infiltrated  with  pus  and  sloughs ;  hence  the  necessity  of  making 
incisions :  for  the  scalp  will  not  lose  its  vitality,  and  liberate  the 
sloughs  like  the  skin  of  other  parts  under  similar  conditions, 


DURA   MATER. 

because  its  vessels  run  above  the  diseased  tissue,  and  therefore  its 
supply  of  blood  is  not  cut  off. 

LYMPHATICS  OF  The  lymphatics  of  the  scalp  run  for  the  most 

THE  SCALP.  part  backwards  towards  the  occiput  to  join  the 

occipital  and  posterior  auricular  glands;  a  few  run  towards  the 
root  of  the  zygoma,  where  they  enter  the  parotid  lymphatic  glands. 
It  is  in  these  situations,  therefore,  that  one  finds  glandular  enlarge- 
ments when  the  scalp  is  diseased. 

To  examine  the  brain  and  its  membranes,  the 

skull-cap  must  be  removed  about  half  an  inch 
above  the  supra-orbital  ridges  in  front,  and  on  a  level  with  the 
occipital  protuberance  behind.  The  student  should  remember  that 
the  bone  in  the  temporal  region  is  very  thin,  and  that  here  especial 
care  is  needed  that  the  brain  be  not  injured  by  the  saw.  It  is 
better  to  saw  only  through  the  outer  table  of  the  skull,  and  to 
break  through  the  inner  with  a  chisel.  In  this  way  the  dura  mater 
and  the  brain  are  less  likely  to  be  injured.  On  removing  the  skull- 
cap, which  is  more  or  less  intimately  attached  to  the  subjacent 
membrane,  we  expose  a  tough  fibrous  layer,  the  dura  mater,  which 
forms  the  most  external  of  the  membranes  of  the  brain. 

The  meningeal  arteries  ramify  between  the  skull  and  the  dura 
mater.  We  cannot,  however,  with  the  brain  in  situ,  trace  their 
course,  at  present,  throughout ;  so  their  consideration  must  be 
deferred  until  the  brain  has  been  removed. 

This  membrane   is  so  called   because  it  was 

thought  to  give  rise  to  all  the  other  fibrous  mem- 
Dranes  in  the  body.  It  is  a  dense  white  fibrous  membrane,  rough 
on  its  outer  aspect,  where  it  is  more  or  less  adherent  to  the  inner 
surface  uf  the  skull,  forming  its  internal  periosteum.  On  its  inner 
surface  it  is  smooth  and  shining,  being  lined  by  a  layer  of  endo- 
thelial  cells,  which  anatomists  now  describe  as  constituting  a  part 
of  the  dura  mater.  In  consequence,  the  term  '  subdural  space '  is 
now  substituted  for  the  old  one — '  the  cavity  of  the  arachnoid.'  The 
dura  mater  differs  in  its  adhesion  to  the  subjacent  bones :  its  ad- 
hesion is  firmest  at  the  sutures,  the  petrous  portion  of  the  temporal 
bone,  the  basilar  process,  the  body  of  the  sphenoid,  the  cribriform 
plate  of  the  ethmoid  bone,  the  depressions  for  the  Pacchionian 


DURA   MATER.  9 

bodies,  and  at  the  margin  of  the  foramen  magnum.  In  front  it 
sends  downwards  a  prolongation  into  the  foramen  csecum  ;  also 
numerous  small  tubular  sheaths  through  the  foramina  in  the 
cribriform  plate.  It  further  sends  a  prolongation  through  the 
optic  foramen,  and  another  through  the  sphenoidal  fissure  into  the 
orbit. 

The  dura  mater  is  supplied  with  nerves  by  the  recurrent  branch 
of  the  fourth  nerve,  and  by  the  fifth  cranial  nerve.  Filaments 
have  likewise  been  traced  into  it  from  the  sympathetic  and  from 
the  Gasserian  ganglion. 

Its  remarkably  tough  and  fibrous  structure  adapts  it  exceed- 
ingly well  to  the  four  purposes  which  it  serves : — 1.  It  forms  the 
internal  periosteum  of  the  skull.  2.  It  forms,  for  the  support  of 
the  lobes  of  the  brain,  three  partitions — namely,  the  falx  cerebri, 
the  falx  cerebelli,  and  the  tentorium  cerebelli.  8.  It  forms  the 
sinuses  or  venous  canals  which  return  the  blood  from  the  brain. 
4.  It  forms  sheaths  for  the  nerves  as  they  leave  the  skull. 

Of  the  partitions  formed  by  the  dura  mater  for  the  support  of 
the  lobes  of  the  brain,  two  are  vertical,  and  separate,  respectively, 
the  two  hemispheres  of  the  cerebrum,  and  those  of  the  cerebellum ; 
the  third  arches  backwards,  and  supports  the  posterior  lobes  of  the 
cerebrum. 

This  partition  is  named,  from  its  resemblance  to 
the  blade  of  a  sickle,  falx  cerebri.     It  is  received 
into  the  longitudinal  fissure,  and  separates  the  two  cerebral  hemi- 
spheres.    It  begins  in  a  point  attached  to  the  crista  galli,  and 
gradually  becomes  broader  as  it  extends  backwards.     Its  upper 
edge  is  convex,  and  attached  to  the  median  groove  on  the  inner 
aspect  of  the  vertex  of  the   skull ;   its  lower  margin  is  concave 
and  free,  and  runs  along  the  upper  aspect  of  the  corpus  callosum. 
From  its  base  or  broadest  part  proceeds  the  sloping  arched  par- 
TENTORIUM  tition  named  tentorium  cerebelli.     This  forms  an 

CEREBELLI.  arch  for  the  support  of  the  posterior  lobes  of  the 

cerebrum,  so  that  they  may  not  press  upon  the  cerebellum  beneath. 
The  tentorium  is  attached  to  the  transverse  ridge  of  the  occipital 
bone,  to  the  superior  border  of  the  petrous  portion  of  the  temporal 
bone,  and  to  the  posterior  and  anterior  clinoid  processes  of  the 


10  GLA^DUL^E   PACCHIONI. 

sphenoid.  In  front  there  is  a  large  oval  opening  to  allow  of  the 
passage  of  the  crura  cerebri.  The  small  median  partition  which 

separates  the  lobes  of  the  cerebellum  is  called  the 
FALX  CEKEBELLI.         *  . 

falx  cerebelh.     It  is  placed  vertically  in  the  same 

plane  with  the  falx  cerebri,  and  its  point  is  downwards  towards  the 
foramen  magnum.  As  it  approaches  the  foramen  it  usually  divides 
into  two  small  folds. 

GLANDULE  In  the  neighbourhood  of  the  superior  longitu- 

PACCHIONI.  dinal  sinus,  we  meet  with  small  white  elevated 

granulations,  sometimes  arranged  singly,  sometimes  in  clusters, 
which  are  received  into  the  depressions  on  the  inner  aspect  of  the 
skull-cap.  They  are  termed  glandulce  Pacchioni,1  and  are  found  in 
four  situations  : — 1.  On  the  outside  of  the  dura  mater,  close  to  the 
superior  longitudinal  sinus,  and  so  large  as  to  occasion  depressions 
in  the  bones.  2.  Along  the  margin  of  the  fissure  of  Sylvius.  3.  On 
the  surface  of  the  pia  mater.  4.  In  the  interior  of  the  superior 
longitudinal  sinus,  covered  by  its  lining  membrane.  5.  On  the  poste- 
rior and  antero-inferior  parts  of  the  posterior  lobe  of  the  cerebrum. 
They  are  due  to  an  increased  growth  of  the  villi,  which  are 
normally  found  in  the  arachnoid  membrane,  and  make  their  way, 
through  the  dura  mater  or  the  pia  mater,  to  the  different  situations 
in  which  they  are  found.  The  greatest  growth  takes  place  from 
the  visceral  layer,  as  may  be  seen  in  the  dissection  of  the  brain. 
These  bodies  are  not  found  at  birth,  but  usually  commence  their 
growth  about  the  third  year,  and  are  always  found  at  the  seventh 
year,  after  which  they  gradually  increase  as  life  advances.2 

SINUSES  OF  THE  It  is  one  of  the  peculiarities  of  the  cerebral  cir- 
DUBA  MATER.  culation,  that  the  blood  is  returned  through  canals 

or  sinuses  formed  by  the  dura  mater.  These  canals  are  produced 
by  a  splitting  of  the  dura  mater  into  two  layers  as  shown  in  fig.  4, 
where  1  represents  a  vertical  section  through  the  superior  longitu- 
dinal sinus.  They  are  lined  by  the  same  smooth  membrane  con- 
tinuous with  that  of  the  venous  system.  Since  their  walls  consist 
of  unyielding  structure,  and  are  always  on  the  stretch,  it  is  obvious 

1  After  the  Italian  anatomist  who  first  described  them,  in  1705. 

2  It  is  stated  that  when  fluid  is  injected  into  the  subarachnoid  space  it  passes 
into  the  Pacchionian  bodies. 


SINUSES   OF   THE   DURA   MATER. 


11 


FIG.  4. 


that  they  are  admirably  adapted  to  resist  the  pressure  of  the  brain. 
There  are  fifteen  of  these  sinuses,  and  they 
are  classified  into  two  groups — a  supero- 
posterior  and  an  infer o-anterior.  The  supero- 
posterior  group  comprises  the  superior  lon- 
gitudinal, the  inferior  longitudinal,  the 
straight,  the  lateral,  and  the  occipital 
sinuses ;  while  the  infero-anterior  group 
includes  the  cavernous,  the  circular,  the 
superior  and  inferior  petrosal,  and  the  straight  sinuses.  Of  these 
fifteen  sinuses,  five  are  pairs  and  five  are  single,  as  follows  : — 


DIAGRAM   TO   SHOW   FOEJIA- 
TION   OF   A   SINUS. 


The  five  pairs  of  sinuses  are  — 
The  lateral. 
The  superior  petrosal. 
The  inferior  petrosal. 
The  cavernous. 
The  occipital. 


The  five  single  sinuses  are — 

The  superior  longitudinal. 
The  inferior  longitudinal. 
The  circular. 
The  transverse. 
The  straight. 


FIG.  5. 


The  blood  from  all   these  sinuses   is   eventually  discharged  into 
the  internal  jugular  veins. 

SUPERIOR  LON-  This  runs  along  the  upper  attached  border  of 

GITUDINAL  SINUS.  the  falx  cerebri  (fig.  5).  It  begins  very  small  at 
the  foramen  caecum,  gradually  increases  in  size  in  its  course  back- 
wards, and  opposite  the  internal 
protuberance  of  the  occipital  bone 
opens  into  a  triangular  dilata- 
tion, the  torcular  Heropldli,  or  the 
confluence  of  the  sinuses.  It  then 
divides  into  the  right  and  left 
lateral  sinuses,  the  right  being 
generally  the  larger.  Besides 
numerous  vein's  from  the  cancel- 
lous  texture  of  the  skull-cap,  the 
superior  longitudinal  sinus  re- 
ceives large  veins  from  the  upper 
part  of  each  hemisphere  of  the  cerebrum,  and  an  emissary  vein 
through  the  parietal  foramen.  It  is  interesting  to  observe  that 
these  veins  run  (as  a  rule)  from  behind  forwards,  contrary  to  the 


1.  Superior  longitudinal  sinus. 

2.  Inferior  longitudinal  sinus. 

3.  Straight  sinus. 

4.  4.  Venae  Galeni. 


12  EEMOVAL   OF  THE   BRAIN. 

current  of  blood  in  the  sinus,  and  that  they  pass  through  the  wall 
of  the  sinus  very  obliquely,  like  the  ureter  into  the  bladder.  The 
probable  object  of  this  oblique  entrance  is  to  prevent  regurgitation 
of  blood  from  the  sinus  into  the  veins  of  the  brain. 

Cut  open  the  superior  longitudinal  sinus :  observe  that  it  is 
triangular  with  its  base  upwards,  and  that  its  cavity  is  intersected 
in  many  places  by  slender  fibrous  cords,  termed  chordce  Willisii.1 
Their  precise  use  is  not  understood. 

The  brain  should  now  be  removed,  and  preserved  in  spirit  for 
future  examination.  Its  anatomy,  with  that  of  its  remaining 
membranes,  will  be  described  in  a  subsequent  part  of  this  work. 

The  brain  is  to  be  removed  in  the  following 
DISSECTION 

manner  : — The  dura  mater  should  be  cut  through 

with  a  pair  of  scissors  on  a  level  corresponding  with  the  sawn  cal- 
varium,  care  being  taken  to  cut  completely  through  the  falx  cerebri 
in  the  front  part  of  the  longitudinal  fissure.  When  this  has  been 
done  the  dura  mater  can  be  easily  turned  back  over  the  brain, 
leaving  its  smooth,  convex  surface  exposed.  Now  lift  up  gently, 
with  the  fingers  of  the  left  hand,  the  frontal  lobes  from  the  anterior 
fossae,  taking  care  to  raise  with  the  brain  the  soft  olfactory  lobes 
from  the  cribriform  plate  of  the  ethmoid.  Two  white  flat  nerves — 
the  optic — come  into  view  prior  to  their  leaving  the  skull  through 
the  optic  foramina;  these  must  be  divided  with  a  sharp  knife 
together  with  the  ophthalmic  arteries  which  lie  beneath  the  corre- 
sponding nerves.2  In  the  middle  line,  fixed  firmly  in  the  sella 
turcica,  lies  the  pituitary  body,  attached  to  the  brain  by  a  process — 
the  infundibulum.  It  is  not  easy  to  remove  this  body  from  the 
fossa  in  which  it  rests,  owing  to  its  being  retained  in  its  position 
by  dura  mater.  When  this  is  removed,  two  round  white  nerves — 
the  third — are  observed,  one  on  each  side,  lying  on  the  inner  free 
border  of  the  tentorium  cerebelli,  immediately  behind  the  anterior 
clinoid  process  of  the  sphenoid.  Divide  these  and  then  proceed 
to  cut  through  the  tentorium  cerebelli  close  to  its  attachment  to 

1  So   called  after  Willis,  who  first  described  them  in  his  work  De  Cerebri 
Anatome,  1664. 

2  It  is  well  that  each  pair  of  nerves  should  be  cut  through  first  on  one  side  and 
then  on  the  other,  before  passing  on  to  the  nerve  next  in  numerical  order. 


LATERAL   SINUSES.  13 

the  posterior  clinoid  process  and  the  upper  border  of  the  petrous 
portion  of  the  temporal  bone,  as  far  back  as  the  lateral  sinus.  If 
this  be  done  with  care,  the  nerves  lying  beneath  the  tentorium  will 
not  have  been  injured.  Immediately  external  to  the  third  nerves 
are  the  slender  fourth  nerves ;  and  still  further  outside  are  the  soft 
flattened  fifth  nerves.  Cut  these  through,  still  gently  raising  the 
brain  from  the  skull  base,  when  the  seventh  pair  come  into  view 
as  they  pass  backwards  and  outwards  towards  the  internal  auditory 
foramina.  When  these  have  been  cut,  we  notice  the  two  sixth 
nerves  running  directly  forwards  to  pierce  the  dura  mater  covering 
the  basilar  process  of  the  occiput.  Divide  these  as  they  pierce  the 
dura  mater,  when  the  three  divisions  of  the  eighth  are  brought  well 
into  view,  lying  behind  and  internal  to  the  seventh ;  the  anterior 
one  is  the  glosso-pharyngeal,  the  middle  one  is  the  pneumogastric, 
and  the  hindermost  one  is  the  spinal  accessory,  whose  spinal  por- 
tion can  be  traced  coming  up  from  the  foramen  magnum.  These 
all  emerge  through  the  jugular  foramina.  Below  and  internal  to 
these  are  the  hypoglossal  nerves,  which  usually  pass  through  the 
dura  mater  in  two  fasciculi.  Cut  these,  and  then  pass  down  the 
knife  as  far  into  the  spinal  canal  as  possible,  and  cut  through  the 
spinal  cord,  the  two  vertebral  arteries,  and  the  spinal  portions  of 
the  spinal  accessory  nerves.  Now  lay  the  knife  aside,  when  by 
gentle  traction  the  brain  can  be  easily  removed  from  the  skull. 

The  other  sinuses  should  now  be  examined. 

LATERAL  These  are  the  two  great  sinuses  through  which 

SINUSES.  all  the  blood  from  the  brain  is  returned  to  the 

jugular  veins.  Their  course  is  well  marked  in  the  dry  skull.  The 
right  is  usually  the  larger.  Each  commences  at  the  internal 
occipital  protuberance,  and  proceeds  at  first  horizontally  outwards, 
enclosed  between  the  layers  of  the  tentorium,  along  a  groove  in 
the  occipital  bone  and  the  posterior  inferior  angle  of  the  parietal ; 
it  then  descends  along  the  mastoid  portion  of  the  temporal  bone, 
and  again  indenting  the  occipital  bone,  turns  forwards  to  the 
foramen  lacerum  posterius,  and  terminates  in  the  bulb  of  the 
internal  jugular  vein,1  where  it  is  joined  by  the  inferior  petrosal 

1  It  has,  in  some  subjects,  another  outlet,  through  the  foramen  mastoideum, 
or  else  through  the  posterior  condylar  foramen. 


14  SINUSES   OF   THE   DURA   MATER. 

sinus.  It  receives  blood  also  from  the  inferior  cerebral  and  cere- 
bellar  veins,  from  the  diploe,  and  the  superior  petrosal  sinus. 
It  communicates  with  the  veins  of  the  scalp  through  emissary 
veins,  which  pass  through  the  mastoid  and  posterior  condylar 
foramina. 

INFERIOR  LON-  This  is  of  small  size.     It  runs  in  the  inferior 

OITUDINAL  SINUS.  free  border  of  the  falx  cerebri,  and  terminates  in 
the  straight  sinus  at  the  anterior  margin  of  the  tentorium  (fig.  5). 

This  may  be  considered  as  the  continuation  of 
STRAIGHT  SINUS.       ,  ,.  T  ,  ,1      v          p  •        .L- 

the  preceding.     It  runs  along  the  hne  01  junction 

of  the  falx  cerebri  with  the  tentorium  cerebelli,  and  terminates  in 
the  torcular  Herophili  at  the  divergence  of  the  two  lateral  sinuses. 
It  receives  the  inferior  cerebral  and  the  superior  cerebellar  veins, 
and  also  the  two  vence  Galeni  (fig.  5),  which  return  the  blood  from 
the  lateral  and  third  ventricles  of  the  brain. 

CAVERNOUS  This  is  so  called  because  its  interior  is  inter- 

SINUS.  sected  by  numerous  cords.     It  extends  along  the 

side  of  the  body  of  the  sphenoid  bone,  outside  the  internal  carotid 
artery.  It  receives  the  ophthalmic  vein  which  leaves  the  orbit 
through  the  sphenoidal  fissure  and  the  anterior  inferior  cerebral 
veins;  it  communicates  with  the  circular  sinus  which  surrounds 
the  pituitary  body  (fig.  6).  At  the  apex  of  the  petrous  portion  of 
the  temporal  bone  it  divides  into  the  superior  and  inferior  petrosal 
sinuses. 

This  surrounds  the  pituitary  body  (p  in  the  dia- 

ClRCULAR  SlNUS.  AC         C\  1  •  T-       '3  'j.1, 

gram  (tig.  o),  and  communicates  on  each  side  with 
the  cavernous  sinus.     The  posterior  branch  is  sometimes  absent. 

PETROSAL  These  lead  from  the  cavernous  to  the  lateral 

SINUSES.  sinuses.     There  are  two  on  each  side.     The  supe- 

rior runs  along  the  upper  portion  of  the  pars  petrosa,  in  the  attached 
border  of  the  tentorium  eerebelli ;  the  inferior,  the  larger  of  the 
two,  runs  along  the  suture  between  the  pars  petrosa  and  the  occi- 
pital bone,  and  ends  in  the  lateral  sinus  just  before  this  terminates 
in  the  internal  jugular  vein.  The  superior  sinus  receives  the  in- 
ferior cerebral,  the  superior  cerebellar  veins,  and  a  small  branch 
from  the  tympanum ;  the  inferior  sinus  is  joined  by  the  inferior 
cerebellar  and  auditory  veins. 


SINUSES   OF   THE   DURA   MATER. 


15 


TEANSVEESE 
SINUS. 


This  extends  from  one  inferior  petrosal  to  the 
other,  across  the  basilar  process  of  the  occipital 
bone.     It  communicates  below  with  the  anterior  spinal  veins. 

OCCIPITAL  These  are  very  small.     They  commence  around 

SINUSES.  the  margin  of  the  foramen  magnum,  run  in  the 

falx  cerebelli,  and  uniting  to  form  a  single  sinus,  opens  into  the 


FIG.  6. 


Third  nerve  .... 
Fourth  nerve  .  .  . 
Sixth  nerve  .... 
First  branch  of  the  I 
fifth } 


Superior  petrosal  sinus 
Inferior  petrosal  sinus 


Ophthalmic  vein. 


Carotid  artery. 
Cavernous  sinus. 


DIAGEAM   OF   THE   VENOUS   SINUSES   AT   THE   BASE   01?   THE   SKULL. 

torcular  Herophili.1     They  join  inferiorly  with  the  posterior  spinal 
veins. 

1  The  junction  of  the  several  sinuses  opposite  the  spine  of  the  occipital  bone  is 
termed  the  torcular  Herophili,  after  the  celebrated  anatomist  who  first  described  it. 
It  is  a  kind  of  triangular  reservoir,  with  the  base  below,  and  presents  six  openings 
— namely,  that  of  the  superior  longitudinal  sinus,  those  of  the  two  lateral  and  of 
the  two  occipital,  and  that  of  the  straight  sinus.  The  term  torcular  is  an  incorrect 
version  of  the  original  word  ff<a\l\v  (a  canal  or  gutter)  employed  by  Herophilus. 


16  MENINGEAL    ARTERIES. 

MENINGEAL  These  arteries  ramify  between  the  skull  and  the 

ARTERIES.  dura  mater.     Their  course  may  be  traced  by  the 

grooves  which  they  make  in  the  bones.  They  are  termed  anterior, 
middle,  and  posterior,  from  the  fossge  in  which  they  ramify. 

The  anterior  meningeal  are  derived  from  the  ethmoidal  branches  of 
the  ophthalmic  artery  and  the  cavernous  portions  of  the  internal  carotid. 
They  supply  the  dura  mater  in  the  neighbourhood  of  the  ethmoid  bone. 

The  middle  meningeal  are  three  in  number  :  the  most  important  is 
the  arteria  meningea  media,  a  branch  of  the  internal  maxillary  artery. 
It  enters  the  skull  through  the  foramen  spinosum,  and  divides  into  two 
principal  branches  :  one,  the  anterior,  runs  in  a  groove  near  the  anterior 
border  of  the  parietal  bone  ;  the  other,  the  posterior,  curves  backwards 
over  the  temporal  bone,  and  subsequently  ramifies  on  the  parietal  bone. 
The  artery  gives  off  a  small  branch — the  petrosal,  which  enters  the 
hiatus  Fallopii  and  anastomoses  with  the  stylo-mastoid  artery  in  the 
aqujeductus  Fallopii  ;  one  or  more  anastomosing  branches  which  enter 
the  orbit  through  the  sphenoidal  fissure  to  communicate  with  the 
ophthalmic  artery ;  and  some  temporal  branches  which  pierce  the 
sphenoid  bone  to  enter  the  temporal  fossa.  It  is  accompanied  by  two 
veins  which  empty  themselves  into  the  internal  maxillary  vein.  The 
arteria  meningea  parva,  which  enters  the  skull  through  the  foramen 
ovale,  and  a  meningeal  branch  from  the  ascending  pharyngeal  artery, 
which  comes  up  through  the  foramen  lacerurn  medium,  also  supply  the 
dura  mater  and  bones  of  the  middle  fossa. 

The  posterior  meningeal  come  from  the  occipital,  the  ascending 
pharyngeal  and  the  vertebral  arteries  ;  the  two  former  enter  the  skull 
through  the  foramen  jugulare,  and  the  latter  through  the  foramen 
magnum.  The  meningeal  veins  with  the  exception  of  the  middle 
meningeal,  open  into  the  various  sinuses. 

,  The  position  of  the  meningeal  arteries  renders  them  liable  to 
injury  in  fractures  of  the  skull ;  hence  extravasation  of  blood 
between  the  skull  and  dura  mater  is  one  of  the  common  causes  of 
compression  of  the  brain. 

The  student  should  now  examine  the  cranial 
nerves  as  they  pass  out  through  the  foramina  in 
the  base  of  the  skull,  and  then  dissect  the  cavernous  sinus. 

EXIT  OF  THE  The  cranial  nerves  proceed  in  pairs  through  the 

CRANIAL  NERVES.       foramina  at  the  base  of  the  skull ;  they  are  named 


EXIT  OF  THE  CRANIAL  NERVES.  17 

first,  second,  third,  fourth,  &c.,  pairs,  according  to  the  order  of  suc- 
cession from  before  backwards.  As  they  pass  through  the  foramina, 
each  receives  a  process  from  the  three  membranes  of  the  brain, 
the  dura  mater,  the  pia  mater,  and  the  arachnoid  ;  the  two  first  are 
gradually  lost  upon  the  nerve,  while  the  arachnoid  is  reflected  back. 

The  first  is  the  olfactory  nerve.  This  cannot  be  seen,  because 
the  olfactory  bulb  has  been  removed  with  the  brain.  From  the 
under  aspect  of  the  bulb  proceed  about  twenty  branches,  which 
pass  through  the  foramina  in  the  cribriform  plate  of  the  ethmoid 
bone,  and  are  arranged  in  three  groups — inner,  middle,  and  outer. 
The  inner  (larger)  pass  to  the  septum  nasi ;  the  middle  to  the  roof 
of  the  nose ;  and  the  outer  to  the  outer  wall  of  the  nose  as  low  as 
the  middle  turbinated  bone. 

The  second  (optic  nerve)  passes  through  the  foramen  opticum 
into  the  orbit  accompanied  by  the  ophthalmic  artery. 

In  order  to  see  the  next  three  pairs  of  nerves,  the  dura  mater 
must  be  carefully  removed  from  the  side  of  the  body  of  the 
sphenoid,  and  the  nerves  traced  as  they  pass  through  the  tentorium 
cerebelli. 

The  third  (motor  oculi)  passes  through  the  dura  mater,  close 
behind  the  anterior  clinoid  process,  traverses  the  outer  wall  of  the 
cavernous  sinus,  and  enters  the  orbit  through  the  sphenoidal  fissure, 
where  it  receives  some  filaments  from  the  cavernous  plexus  of  the 
sympathetic.  Before  passing  through  the  fissure,  it  divides  into 
two  branches,  an  upper  and  a  lower,  which  enter  the  orbit  between 
the  two  heads  of  the  external  rectus. 

The  fourth  (trochlearis),  a  small  nerve,  passes  through  the  dura 
mater  a  little  behind  the  posterior  clinoid  process.  It  passes 
through  the  outer  wall  of  the  cavernous  sinus,  lying  below  the 
preceding  nerve  and  above  the  first  division  of  the  fifth,  and  then 
runs  forwards  through  the  sphenoidal  fissure.  Here  it  lies  above 
the  third  nerve,  and  is  finally  distributed  to  the  superior  oblique 
muscle,  on  its  orbital  surface.  In  passing  through  the  cavernous 
sinus  it  receives  some  branches  from  the  sympathetic  plexus.  It 
also  communicates  here  with  the  ophthalmic  nerve,  and  sends 
back  a  recurrent  branch  to  supply  the  tentorium  cerebelli  as  far 
back  as  the  internal  occipital  protuberance. 

c 


18 


EXIT   OF   THE   CRANIAL   NERVES. 


The  fifth  (trifacial)  nerve  passes  through  an  aperture  in  the 
dura  mater  beneath  the  tentorium  cerebelli,  just  above  the  apex  of 
the  petrous  portion  of  the  temporal  bone.  It  consists  of  two  parts 


Ninth  nerve 
Tenth  nerve     . 
Eleventh  nerve 


FIG.  7. 


Olfactory  bulb      .    .    .     - 


Optic  nerve 


Third  nerve 


DIAGRAM   OF   THE   EXIT   OF   THE    CEANIAL   NEKVES. 

— a  larger  or  sensory  root,  and  a  smaller  or  motor.  Upon  its 
larger  or  sensory  root  is  developed  a  large  ganglion,  the  Gasserian 
ganglion ;  while  the  motor  root  lies  below  and  unconnected  with 


EXIT  OF  THE  CRANIAL  NERVES.  19 

it.  From  this  ganglion  proceed  the  three  primary  divisions  of  the 
nerve — the  ophthalmic,  which  passes  through  the  outer  wall  of  the 
cavernous  sinus  below  the  fourth  nerve,  and  subsequently  enters 
the  orbit  through  the  sphenoidal  fissure  ;  while  in  the  cavernous 
sinus  this  nerve  receives  filaments  of  communication  from  the 
cavernous  plexus,  and  also  sends  back  a  recurrent  branch  to  supply 
the  tentorium  cerebelli  (Arnold) ;  the  ophthalmic  nerve  is  fre- 
quently intimately  connected  with  a  branch  from  the  fourth  nerve : 
it  is  also  connected  by  a  small  branch  with  the  sixth  nerve ;  the 
superior  maxillary,  which  gives  off  a  small  recurrent  branch  to  the 
dura  mater  and  middle  meningeal  artery,  and  then  leaves  the  skull 
through  the  foramen  rotundum  ;  and  the  inferior  maxillary,  which 
passes  through  the  foramen  ovale.  The  smaller  or  motor  root  of 
the  fifth  lies  beneath  the  ganglion,  with  which  it  has  no  communi- 
cation, and  then  joins  the  inferior  maxillary  division  to  supply  the 
muscles  of  mastication  with  motor  power. 

The  sixth  (abducens)  nerve  pierces  the  dura  mater  behind  the 
body  of  the  sphenoid  bone,  which  it  grooves.  It  then  passes  along 
the  inner  wall  of  the  cavernous  sinus,  external  to  the  internal 
carotid  artery,  and  enters  the  orbit  through  the  sphenoidal  fissure 
to  supply  the  external  rectus,  between  the  two  heads  of  which  it 
passes.  It  is  connected,  as  it  passes  along  the  inner  wall  of  the 
cavernous  sinus,  with  the  cavernous  plexus,  the  ophthalmic  nerve, 
and  in  the  orbit  with  Meckel's  ganglion. 

The  seventh  or  facial  nerve  passes  through  the  meatus  audi- 
torius  internus  together  with  the  auditory  nerve  and  artery.  As  it 
passes  along  the  meatus  it  is  separated  from  the  auditory  nerve, 
upon  which  it  lies,  by  the  portio  intermedia.  At  the  bottom  of  the 
auditory  meatus,  the  facial  nerve  leaves  the  auditory  to  traverse  a 
tortuous  bony  canal,  the  'aquasductus  Fallopii.'  In  the  meatus 
auditorius,  the  facial  and  the  auditory  nerves  are  connected  by 
small  filaments. 

The  eighth  or  auditory  nerve  passes  outwards  through  the 
internal  auditory  meatus  in  company  with  the  preceding  nerve. 
It  is  the  larger  of  the  two  nerves,  and  lies  below  the  facial,  which 
lies  in  a  groove  on  this  nerve.  In  the  meatus  the  auditory  divides 
into  two  branches,  cochlear  and  vestibular. 

c  2 


20 


EXIT   OF   THE   CRANIAL   NERVES. 


The  ninth  or  glosso-pharyngeal  nerve  passes  through  the  jugular 
foramen  in  front  of  the  pneumogastric  and  spinal  accessory  nerves. 
This  nerve  has  a  separate  tube  of  dura  mater  and  arachnoid,  and 
lies  in  a  groove  in  the  lower  border  of  the  pars  petrosa  of  the 
temporal  bone  together  with  the  two  succeeding  nerves  (fig.  8). 

FIG.  8. 


INF.FETROSAL 
SINUS 


INT.AUD.MEATUS 


SSO-PHARYNGEAL 
PNEU  MO-GASTRIC 
SPINAL  ACCESSORY 
LATERAL  SINUS 


DIAGRAM    SHOWING   THE   RELATIONS   OF   THE   VESSELS   AND   NERVES   PASSING    THROUGH 
THE    FORAMEN   JUGULARS. 

The  tenth  or  pneumogastric  nerve  emerges  through  the  jugular 
foramen  behind  and  rather  internal  to  the  glosso-pharyngeal.  It 
is  enclosed  in  a  common  sheath  of  dura  niater  with  the  spinal 
accessory,  but  is  separated  from  it  by  a  thin  septum  of  arachnoid 
membrane. 

The  eleventh  or  spinal  accessory  also  passes  through  the  foramen 
jugulare,  lying  behind  the  preceding  nerve. 

The  twelfth  or  hypoglossal  nerve  passes  through  the  anterior 
condylar  foramen,  piercing  the  dura  mater  by  two  fasciculi  which 
unite  external  to  the  skull.1 


1  According  to  the  classification  adopted  by  Willis,  the  cranial  nerves  are 
arranged  in  nine  pairs  :  the  seventh  including  the  facial  and  the  auditory ;  the 
eighth  comprising  the  glosso-pharyngeal,  the  pneumogastric,  and  the  spinal  acces- 
sory. The  arrangement  adopted  in  this  handbook  is  that  by  Sommering. 


NERVES   PASSING   THROUGH   CAVERNOUS   SINUS.  21 

We  must  now  examine  the  cavernous  sinus,  and 
the   nerves   which  course  along   its  walls  to  the 
orbit — namely,  the  third,  the  fourth,  the  ophthalmic  division  of  the 
fifth  and  the  sixth  nerves. 

CAVERNOUS  This  sinus  (fig.  6)  lies  by  the  side  of  the  body 

SINUS.  of  the  sphenoid  bone.     In  front  it   receives  the 

ophthalmic  vein,  which  passes  backwards  through  the  sphenoidal 
fissure  ;  while  posteriorly  it  divides  into  the  superior  and  inferior 
petrosal  sinuses,  which  have  been  already  described  ;  on  the  inner 
side  it  communicates  with  the  circular  sinus,  which  surrounds  the 
pituitary  body  (P  in  the  diagram  6).  The  interior  of  the  sinus  is 
remarkable  for  the  numerous  fine  bands  of  reticular  tissue  which 
interlace  in  all  directions. 

In  the  outer  wall  of  the  cavernous  sinus  we  trace,  from  above 
downwards,  the  third  nerve,  the  fourth,  and  the  ophthalmic  division 

FIG.  9. 


CAVERNOUS? 'SINUS 
INT.CAROTID   ARTERY 


RELATION   OF   THE   VARIOUS   STRUCTURES   PASSING   THROUGH   THE   CAVERNOUS   SINUS. 

of  the  fifth,  in  their  course  to  the  orbit.  On  its  inner  wall  are 
situated  the  internal  carotid  artery  with  the  sixth  nerve  below  and 
to  its  outer  side.  These  structures  are  not  actually  within  the 
sinus  so  as  to  be  bathed  by  the  blood,  for  they  are  separated  from 
it  by  the  lining  membrane  of  the  sinus  (fig.  9). 

EELATIVE  Posi-  These  nerves  should  be  traced  from  the  cavernous 

TIONS  OF  NERVES  sinus,  forwards,  so  as  to  see  how  they  alter  their  rela- 
IN 'SPHENOIDAL  tive  positions  before  entering  the  sphenoidal  fissure, 

FISSURE.  and,  again,  in  their  passage  through  it. 

Just  before  entering  the  sphenoidal  fiss'ure,  the  fourth  nerve  (on  its 
way  to  the  orbital  surface  of  the  superior  oblique)  gets  above  the  third, 
which  here  divides  into  an.  upper  and  a  lower  branch  (both  proceeding 
to  the  ocular  surface  of  the  muscles  they  supply)  ;  lower  still,  we  have 


22 


NERVES   TO   THE   ORBIT. 


the  frontal,  lachrymal,  and  nasal  divisions  of  the  ophthalmic  ;  lowest  of 
all  is  the  sixth  nerve  on  its  way  to  the  external  rectus. 

In  their  passage  through  the  sphenoidal  fissure,  we  find  that  the 


FIG.  10. 


LACHRYMAL 
FRONTAL 


UPPER   DIVISION  OF  3 
NASA  L 

LOWER  DIVISIONrsfoF  3 
SIXTH 
OPHTHALMIC* VEIN 


DIAGRAM   OF   THE    RELATIONS    OF   THE    NERVES   AS    THEY    PASS   THROUGH 
THE    SPHENOIDAL    FISSURE. 

fourth  nerve,  the  frontal  and  lachrymal  branches  of  the  ophthalmic,  lie 
at  the  top,  on  nearly  the  same  level,  and  they  enter  the  orbit  above  the 
muscles  in  this  order  from  within  outwards.  Lower,  and  in  the  follow- 
ing order  from  above  downwards,  come  the  upper  division  of  the  third 

FIG.  11. 


UPPER   DIV.  OF3R°IMERVE 
LACHRYMAL 

SIXTH    NERVE. 
CILIARY  GANGL. 

LOWER  DIV.OFS""1  NERVE 


OPTIC. N. 
RELATIONS  OF  THE  NERVES  AND  MUSCLES  AT  THE  BACK  OF  THE  ORBIT. 

the  nasal  branch  of  the  ophthalmic,  the  lower  division  of  the  third,  and 
the  sixth  ;  all  of  which  (with  the  ophthalmic  vein)  enter  the  orbit 
between  the  two  origins  of  the  rectus  externus  (fig.  10). 


CAROTID  .ARTERY  IN   THE   CAVERNOUS   SINUS. 


23 


FIG.  12. 


At  the  back  of  the  orbit  the  relation  of  these  nerves  is  further 
altered.  The  fourth,  frontal  and  lachrymal,  are  still  on  the  same  level  : 
the  upper  division  of  the  third  is  below  the  superior  rectus,  and  above 
the  optic  nerve  is  the  nasal  n.;  the  sixth  is  on  the  inner  side  of  the 
external  rectus,  while  the  lower  division  of  the  third  is  below  and  to 
the  outer  side  of  the  optic  nerve,  close  to  which  is  the  lenticular  ganglion 
(fig.  11). 

The  dissector  will  better  remember  the  varying  relations  of  these 
nerves,  when  he  has  learnt  their  respective  destinations. 

CURVES  or  THE  After  the  removal  of  the  cavernous  sinus,  a  good 

CAROTID  ARTERY.  view  is  obtained  of  the  curves,  like  the  letter  S, 
made  by  the  internal  carotid  artery  *6n  the  side  of  the  pituitary 
fossa.  The  vessel  enters  the  cranium  at  the  apex  of  the  petrous 
portion  of  the  temporal  bone,  makes  its  sigmoid  curves  within  the 
cavernous  sinus,  and  then  passes 
through  the  dura  mater,  between 
the  anterior  clinoid  process  and  the 
optic  nerve,  where  it  gives  off  the 
ophthalmic  artery.  Within  the 
cavernous  sinus,  small  branches, 
arterice  receptaculi,  arise  from  the 
carotid  and  supply  the  pituitary 
body,  and  the  walls  of  the  sinus. 

A  careful  dissection  would  show 
a  plexus  of  sympathetic  nerves  on 
the  outer  side  of  the  internal  carotid 
artery,  as  it  lies  by  the  side  of  the 
body  of  the  sphenoid.  This  is  the 
CAROTID  PLEXUS.  It  is  connected  by 
numerous  filaments  with  the  sixth 
nerve  and  the  Gasserian  ganglion. 
It  further  furnishes  the  large  deep 
petrosal  nerve  which  unites  with 
the  large  superficial  petrosal  nerve 
of  the  facial  to  form  the  Vidian; 
and  also  the  small  deep  petrosal  nerve  which  joins  probably  the 
tympanic  plexus.  Those  filaments  of  the  sympathetic  seen  on  the 


THE   GENICULATE    GANGLION   OF   THE 
FACIAL    NERVE. 

1.  The  chorda  tympani. 

2.  The  geniculate  ganglion  of  the  facial 

nerve. 

3.  The  great  petrosal  nerve. 

4.  The  lesser  petrosal  nerve  lying  over  the 

tensor  tympani. 

5.  The  external  petrosal  nerve  communi- 

cating with  the  sympathetic  plexus  on 
the  arteria  meningea  media  (6). 
7.  The  Gasserian  ganglion. 


24  DISSECTION   OF  THE   FACE. 

inner  side  of  the  artery  in  the  upper  part  of  the  cavernous  sinus 
constitute  the  CAVEENOUS  PLEXUS,  which  is  in  communication 
with  the  third,  the  fourth,  and  the  ophthalmic  division  of  the 
fifth  nerves,  and  gives  a  branch  to  the  lenticular  ganglion  in  the 
orbit. 

On  removing  the  Gasserian  ganglion,  three  small  nerves  are 
seen  lying  on  the  anterior  surface  of  the  petrous  portion  of  the  tem- 
poral bone.  One,  the  large  superficial  petrosal  nerve,  enters  the 
hiatus  Fallopii  to  join  the  facial ;  the  second,  immediately  exter- 
nal to  the  preceding,  is  the  small  superficial  petrosal,  which  passes 
from  the  facial  to  join  the  otic  ganglion ;  the  third,  the  external 
superficial  petrosal  nerve  (not  always  present),  passes  from  the 
facial  to  communicate  with  the  sympathetic  on  the  middle  menin- 
geal  artery. 

DISSECTION   OF   THE   FACE. 

Much  practice  is  required  to  make  a  good  dissection  of  the 
face,  and  it  is  well,  therefore,  to  dissect  this  part  before  the  skin 
and  subjacent  structures  get  dry  and  discoloured. 

The  muscles  of  expression  are  numerous  and  complicated ;  they 
are  interwoven  with  the  subcutaneous  tissue  and  closely  united  to 
the  skin  :  their  fibres  are  often  pale  and  indistinct.  The  face  is 
largely  supplied  with  motor  and  sensory  nerves,  of  which  the  rami- 
fications extend  far  and  wide.  Therefore  you  must  not  be  dis- 
couraged if,  in  a  first  attempt,  you  fail  to  make  a  satisfactory  display 
of  the  parts. 

The  cheeks  and  nostrils  should  be  distended  with  horse-hair, 
and  the  lips  sewn  together. 

Make  an  incision  down  the  mesial  line  of  the  face ;  another 
from  the  chin  along  the  base  of  the  lower  jaw  to  the  angle ;  then 
prolong  it,  in  front  of  the  ear,  to  the  zygoma.  Reflect  the  skin 
from  below  upwards.  Each  muscle,  to  be  properly  cleaned,  should 
be  put  on  the  stretch  by  hooks. 

The  student  is  recommended  to  make  out  the  muscles  and 
arteries  on  the  one  side,  leaving  the  other  side  for  the  display  of 
the  nerves. 


DISSECTION   OF   THE   FACE.  25 

The  motor  nerve  which  supplies  all  the  muscles  of  expression 
in  the  face  is  the  '  portio  dura,'  or  facial  nerve.  It  emerges  from 
the  stylo-mastoid  foramen,  and  divides  into  branches,  which  pass 
through  the  parotid  gland,  forming  a  plexus  termed  the  lpes 
anserinus.' 

The  sensory  nerves  of  the  face  are  chiefly  derived  from  the  three 
divisions  of  the  fifth  cranial  nerve ;  namely,  the  supra-orbital,  the 
supra-trochlear,  the  lachrymal,  the  infra-trochlear,  and  nasp-lobular, 
which  latter  supply  the  ala  and  the  tip  of  the  nose ;  the  three 
sets  of  branches  from  the  infra-orbital ;  and  the  mental.  The 
other  nerves  which  confer  sensation  upon  the  face  are,  the  great 
auricular  branch  of  the  cervical  plexus,  which  supplies  the  skin 
covering  the  parotid  gland  and  part  of  the  cheek. 

It  is  convenient  to  arrange  the  muscles  of  the  face  under  three 
groups  ;  appertaining,  respectively,  to  the  mouth,  the  nose,  the 
eyebrows  and  lids.  Begin  with  those  of  the  mouth. 

The  muscles  of  the  mouth  are  arranged  thus :  there  is  an  orbi- 
cular or  sphincter  muscle  surrounding  the  lips  ;  from  this,  as  from 
a  common  centre,  muscles  diverge  and  are  fixed  into  the  surround- 
ing bones.  They  are  named  elevators,  depressors,  sphincters,  &c., 
according  to  their  respective  action. 

MUSCULUS  This  muscle  is  usually  considered  as  a  part  of 

EISOEIUS  the   platysma    myoides,    the   large    subcutaneous 

(SANTORINI).  muscle  of  the  neck.     It  arises  by  thin  fasciculi 

from  the  fascia  over  the  masseter  muscle,  and  passes  horizontally 
forwards  to  be  inserted  into  the  angle  of  the  mouth,  where  it  inter- 
mingles with  the  orbicularis  oris  and  depressor  anguli  oris.  It 
produces  the  smile,  not  of  good-humour,  but  of  derision. 

ORBICULARIS  This  muscle,  nearly  an  inch  in  breadth,  sur- 

ORIS.  rounds  the  ^mouth,  forming  a  kind  of  sphincter. 

Its  size  and  thickness  in  different  individuals  produce  the  variety 
in  the  prominence  of  the  lips.  Observe  that  its  fibres,  except  the 
most  internal,  do  not  surround  the  mouth  in  one  unbroken  series, 
but  that  those  of  the  upper  and  lower  lip  decussate  at  the  angles  of 
the  mouth,  and  intermingle  with  the  fibres  of  the  buccinator  and 
other  muscles  which  converge  from  different  parts  of  the  face. 

The  orbicularis  consists  of  two  parts,  an  inner  or  labial  part, 


26 


MUSCLES   OF   THE   FACE. 


and  an  outer  or" facial ;  the  difference  in  appearance  of  the  fibres 
being  very  marked.     The  labial  part  consists  of  pale  thin  fibres, 


FIG.  13. 


1.  Kisorius. 

2.  Orbicularis  oris. 

3.  Depressor  anguli  oris. 

4.  Depressor  labii  inferioris. 

5.  Levator  menti. 

6.  Orbicularis  palpebrarum. 

7.  Zygomaticus  major. 

8.  Zygomaticus  minor. 

9.  Pyramidalis  nasi. 

10.  Compressor  naris. 

11.  Levator  labii  superioris  et  ate  nasi. 

12.  Levator  labii  superioris. 

13.  Levator  anguli  oris. 


14.  Buccinator. 

15.  Occipito-frontalis. 

16.  Masseter. 

17.  Sterno-mastoid. 

18.  Trapezius. 

- 19.  Splenius  capitis. 

20.  Digastric. 

21.  Levator  proprius  ate  nasi  anterior, 

or  dilatator  naris  anterior. 

22.  Levator  proprius  ate  nasi  posterior, 

or  dilatator  naris  posterior. 

23.  Platysma  myoides. 

24.  Depressor  ate  nasi. 


forming  more  or  less  of  the  inner  part  of  the  Orbicularis,  and  has 
no  attachment  to  bone ;  the  facial  part  is  thinner  but  broader,  and 
besides  being  connected  with  other  muscles,  is  attached  to  bone 


MUSCLES   OF   THE   FACE.  27 

thus:  in  the  upper  lip  by  two  fasciculi  on  each  side,  one  to  the 
septum  nasi,  the  other  to  the  alveolar  border  opposite  the  incisor 
teeth ;  in  the  lower  lip  by  a  single  fasciculus  to  the  lower  jaw  on 
each  side  opposite  the  canine  tooth.  The  cutaneous  surface  of  the 
muscle  is  intimately  connected  with  the  lips  and  the  surrounding 
skin  ;  the  deep  surface  is  separated  from  the  mucous  membrane  by 
the  labial  glands  and  the  coronary  vessels. 

The  orbicularis  is  the  antagonist  of  all  the  muscles  which  move 
the  lips.  Upon  a  nice  balance  of  their  opposite  actions  depends 
the  play  and  infinitely  varied  expression  of  the  mouth.1 

DEPEESSOR  This  muscle  arises  broadly  from  the  oblique  line 

ANGULI  OKIS.  of  the  lower  jaw  behind  the  foramen  mentale,  and 

is  inserted  narrowly  into  the  angle  of  the  mouth,  intermingling 
with  the  zygomatici,  the  risorius,  and  orbicularis  oris.  It  is  an 
important  muscle  in  the  expression  of  sorrowful  emotions.-  We  see 
its  action  when  children  cry. 

DEPRESSOR  This  muscle  arises  from  the  oblique  line  of  the 

LABII  INFERIOBIS,  lower  jaw  below  the  foramen  mentale,  and  is  in- 
OK  QUADRATUS  serted  into  the  lower  lip,  its  fibres  intermingling 

I-  with  those  of  its  fellow  of  the  opposite  side  and 

the  orbicularis.  It  covers  the  vessels  and  nerves  which  emerge  from 
the  foramen. 

LEVATOR  MENTI  This  muscle  arises  from  the  lower  jaw,  from  the 
OR  LEVATOR  LABII  fossa  below  the  incisor  teeth,  and,  passing  down, 
INFERIOR™.  is  inserted  into  the  skin  of  the  chin.  To  see  it, 

evert  the  lower  lip  and  remove  the  mucous  membrane  on  either 
side  of  the  freenum.  There  are  two  of  them,  one  for  each  side. 
Their  action  is  well  seen  when  we  shave  the  chin,  or  protrude  the 
lower  lip. 

ZYGOMATICUS  The  zygomaticus  major  arises  from  the  outer 

MAJOR  AND  MINOR,  surface  of  the  malar  bone  close  to  its  suture 
with  the  zygoma,  passes  obliquely  downwards  and  inwards,  and  is 

1  In  strong  muscular  lips  the  upper  part  of  the  orbicularis  sends  a  small  sub- 
cutaneous slip  of  muscle  from  each  side  along  the  septum  nasi  nearly  to  the  apex. 
The  interval  between  the  two  slips  corresponds  to  the  furrow  which  leads  from  the 
nose  to  the  lip.  This  is  the  naso-labialis  or  depressor  septi  narium  of  Haller  and 
Albinus. 


28  TENDO   OCULI. 

inserted  into  the  angle  of  the  mouth,  joining  the  depressor  anguli 
and  orbicularis  oris. 

The  zygomaticus  minor  arises  from  the  outer  surface  of  the 
malar  bone,  in  front  of  the  preceding,  and  is  inserted  into  the  outer 
border  of  the  levator  labii  superioris  near  the  corner  of  the  mouth. 
The  zygomaticus  minor  is  often  absent.  The  zygomaticus  major 
is  the  muscle  of  laughing  :  the  minor  expresses  sadness. 

Before  examining  the  orbicularis  palpebrarum,  notice  the  tendo 
oculi.  To  make  the  tendon  more  apparent,  the  tarsal  cartilages 
should  be  drawn  outwards. 

TENDO  OCULI  OK         This  tendon  is  a  thin  cord  about  two  lines  *  in 
PALPEBKARUM.  length,  and  is  readily  felt  at  the  inner  angle  of 

the  eye  by  drawing  the  eyelids  outwards.  It  is  fixed  to  the  nasal 
process  of  the  superior  maxillary  bone,  in  front  of  the  lachrymal 
groove,  passes  horizontally  outwards,  and  divides  into  two  diver- 
ging portions,  one  of  which  is  attached  to  the  upper,  the  other 
to  the  lower  tarsal  cartilage.  The  tendon  crosses  the  lachrymal 
sac  a  little  above  the  centre,  and  furnishes  a  tendinous  expansion 
which  covers  the  sac  and  is  attached  to  the  margin  of  the  bony 
groove  which  contains  it.  To  see  this  expansion  we  must  re- 
flect that  portion  of  the  orbicularis  palpebrarum  which  covers 
the  sac. 

In  puncturing  the  lachrymal  sac  the  knife  is  introduced  below 
the  tendon,  in  a  direction  downwards,  outwards,  and  a  little  back- 
wards. We  have  to  divide  the  skin,  a  few  fibres  of  the  orbicularis, 
and  the  fibrous  expansion  from  the  tendo  palpebrarum.  The 
angular  artery  and  vein  are  situated  on  the  inner  side  of  the 
incision. 

OKBICULAEIS  This  thin  broad  muscle  surrounds  the  margin 

PALPEBKARUM.  of  the  orbit  and  the  eyelids,  forming  a  sphincter. 

It  is  attached  on  the  inner  side  to  the  tendo  palpebrarum,  to 
the  nasal  process  of  the  superior  maxillary  bone,  to  the  internal 
angular  process  of  the  frontal  bone,  and  to  the  lower  margin  of  the 
orbit.  From  this  attachment  the  fibres  form  a  series  of  oval  curves, 
taking  a  wide  sweep,  and  pass  uninterruptedly  round  the  eyelids 
and  orbit. 

1  A  line  is  the  twelfth  part  of  an  inch. 


ORBICULARIS  PALPEBRARUM.  29 

The  fibres  which  belong  to  the  eyelids  (orbicularis  palpebrarum) 
are  thin  and  pale,  and  form,  over  each  eyelid,  a  series  of  elliptical 
curves  which  meet  at  the  external  canthus  of  the  lids,  and  are 
loosely  attached  to  the  external  tarsal  ligament.  The  degree  of 
their  curvature  becomes  less  as  they  approach  the  margin  of  the 
lids,  so  that  some  fibres  proceed  close  to  the  lashes.  This  was 
first  pointed  out  by  Riolanus,1  and  described  as  the  mmculus 
ciliaris?  The  fibres  which  spread  over  the  orbital  margins  (orbital 
portion)  are  thicker  and  redder,  and  mingle,  on  the  forehead, 
with  the  occipito-frontalis  and  corrugator  supercilii,  on  the  cheek, 
with  the  elevators  of  the  upper  lip  and  nose  and  the  zygomaticus 
minor. 

No  fat  is  found  on  the  eyelids  ;  nothing  intervenes  between 
the  skin  and  the  muscles  but  loose  connective  tissue,  that  there 
may  be  no  impediment  to  the  free  play  of  the  lids. 

The  orbicular  muscle  not  only  closes  the  eyelids  but  protects 
the  eye.  When  the  eye  is  threatened,  the  muscle  suddenly  con- 
tracts, presses  the  eye  back  into  the  orbit,  and  contracts  the  skin 
of  the  brow  and  cheek  so  as  to  form  a  soft  cushion  in  front  of  it. 
The  cushion  itself  may  be  severely  bruised,  as  is  seen  in  a  '  black 
eye ; '  but  the  globe  itself  is  rarely  injured.  When  the  eye  is 
closed,  as  in  winking,  the  palpebral  portion  of  the  muscle  contracts. 
Observe  this  movement,  and  notice  that  the  lids  are  drawn  slightly 
inwards  as  well  as  closed.  The  object  of  this  inward  motion  is  to 
direct  the  tears  towards  the  inner  angle  of  the  eyelids,  where  they 
are  absorbed  by  the  puncta  lachrymalia. 

The  tensor  tarsi  muscle  is  described  in  the  dissection  of  the 
orbit. 

Since  the  orbicular  muscle  is  supplied  by  the  facial  nerve,  it  is 
affected  in  facial  palsy,  and  the  patient  cannot  close  the  lids. 

COKBUGATOK  This  arises   from  the  inner  end  of  the  super- 

SUPEBCHJI.  ciliary  ridge  of  the  frontal  bone,  and  is  inserted 

into  the  under  surface  of  the  orbicularis  palpebrarum  and  occipito- 

1  Anthropologia,  lib.  v.  cap.  10. 

2  Strictly  speaking,  the  musculus  ciliaris  arises  from  the  two  little  divisions  of 
the  tendo  oeuli,  and  is  inserted  at  the  external  canthus,  into  the  fibrous  tissue 
which  unites  the  two  tarsal  cartilages. 


30  THE   EYELIDS. 

frontalis.  It  lies  concealed  beneath  these  two  muscles,  and  is 
the  proper  muscle  of  frowning.  Its  nerve  is  derived  from  the 
facial. 

The  present  being  a  good  opportunity  to  examine  the  append- 
ages (tutamina  oculi)  of  the  eyes,  postpone  for  the  present  the 
dissection  of  the  remaining  muscles  of  the  face. 

The  eyelids  are  two  moveable  elliptical  folds 
consisting  of  strata  of  different  tissues.  The 
upper  lid  is  large  and  more  moveable  than  the  lower,  so  that  when 
the  eye  is  closed,  it  is  mainly  by  this  fold.  The  interval  between 
the  two  lids  is  called  the  fissura  palpebrarum,  which  terminates  on 
the  inner  and  outer  sides  in  two  angles,  the  canthi.  The  lids 
are  thickest  at  their  borders,  are  somewhat  curved,  and  near  the 
inner  canthus  each  presents  a  slight  elevation,  the  papilla  lachry- 
malis,  at  the  top  of  which  is  a  small  opening,  the  punctum  lachry- 
mals ;  this  is  the  commencement  of  a  small  canal,  canaliculus, 
which  receives  the  tears  and  conveys  them  to  the  lachrymal  sac, 
and  thence  through  the  nasal  duct  to  the  nose.  At  the  inner 
canthus  the  two  lids  are  separated  by  an  oval  space,  the  lacus 
lachrymalis,  where  the  mucous  membrane  is  raised  into  a  rounded 
eminence,  the  caruncula. 

CAKUNCULA  The  caruncula  lachrymalis  is  the  red  rounded 

LACHEYMALIS.  eminence  situated  at  the  inner  canthus  and  formed 

by  the  conjunctiva.  It  is  composed  of  an  aggregation  of  sebaceous 
and  sweat  glands  covered  by  mucous  membrane ;  on  the  surfade 
of  it  are  minute  hairs.  Resting  upon  the  eyeball  external  to  the 
caruncle  is  a  slight  vertical  triangular  fold  of  conjunctiva,  plica 
semilunaris,  which  is  the  rudimentary  membrana  nictitans  (the 
third  eyelid  found  in  birds).  Both  in  the  caruncle  and  plica 
semilunaris  unstriped  muscular  tissue  has  been  demonstrated. 

The  conjunctiva  is  the  mucous  membrane  which  covers  the  inner 
surface  of  the  lids  and  the  front  of  the  eyeball.  The  portion  lining 
the  lids  is  termed  the  palpebral ;  that  portion  covering  the  front  of 
the  eye,  the  ocular.  The  angle  of  its  reflection  from  the  lids  to 
eyeball  is  called  the  fornix  conjunctives,  where  are  situated  a  number 
of  racemose  glands ;  there  is  also  some  lymphoid  tissue  found  in 
other  parts  of  the  conjunctiva.  The  palpebral  conjunctiva  is  more 


STRUCTURE   OF  THE   EYELIDS.  31 

vascular  than  the  ocular,  and  it  presents  a  number  of  minute 
papillae,  which  when  enlarged  and  aggregated  by  inflammation 
give  rise  to  the  disease  called  '  granular  lids.'  The  conjunctiva 
will  be  more  fully  described  with  the  anatomy  of  the  eye. 

The  eyelashes  (cilia)  are  placed  in  two  or  more  rows  along  the 
edges  of  the  tarsal  cartilages.  The  eyelashes  of  the  upper  lid  are 
longer  and  more  numerous  than  in  the  lower  ;  and  their  convexity 
is  directed  downwards,  while  those  of  the  lower  lid  present  an 
opposite  curve.  The  bulbs  of  the  lashes  are  situated  between 
the  tarsal  cartilage  and  the  fibres  of  the  orbicularis  palpebrarum. 
They  are  supplied  with  blood  by  the  palpebral  branches  of  the 
ophthalmic  artery,  which  run  parallel  and  close  to  the  free  borders 
of  the  lids  beneath  the  orbicular  muscle. 

STRUCTURE  OP  The  eyelids  are  composed  of  different  tissues,  ar- 

THE  EYELIDS.  ranged  in  successive  strata  one  beneath  the  other. 

They  are — 1.  The  skin;  2.  The  orbicularis  palpebrarum;  3.  The 
palpebral  ligament,  which  extends  from  the  margin  of  the  orbit  to 
the  cartilage ;  4.  The  expanded  tendon  of  the  levator  palpebrce  (in 
the  upper  lid  only) ;  5.  The  tarsal  cartilage ;  6.  A  thin  layer  of 
fascia,  in  which  are  seen  the  blood-vessels;  7.  The  Meibomian 
glands,  which  lie  embedded  in  the  tarsal  cartilage  ;  8.  Conjunctiva. 
These  structures  are  severally  connected  by  areolar  tissue,  which 
never  contains  fat. 

Such,  in  outline,  is  the  structure  of  the  eyelids.  Their  use  is 
best  described  by  Socrates,  who,  in  answer  to  the  question  whether 
animals  were  made  by  chance  or  design,  replies  :  '  Think  you  not 
that  it  looks  like  the  work  of  forethought,  because  the  sight  is 
delicate,  to  guard  it  with  eyelids  as  with  shutters,  which  open 
when  we  want  to  see,  and  shut  during  sleep ;  and,  that  even  winds 
may  not  hurt  them,  to  make  eyelashes  in  the  lids  for  a  sieve ; 
and  to  furnish  the  parts  over  the  eyes  with  eyebrows,  as  with 
eaves,  so  that  even  the  sweat  from  off  the  head  may  do  them  no 
mischief  ? ' J 

1  Xenophon's  Memorabilia,  b.  1,  c.  vi.  §  6 :  ov  SOKC?  <TOJ  ical  r6Se  irpovoias  tpyov 
toiKevai,  T6,  eirel  affdfvfys  /J.ev  tcrriv  T)  ttyis,  @\e<pdpois  avrfyv  Qvptaffai,  a,  OTO.V  fj.ev  avrfj 
XpTJffOai  rt  Sej?,  avaarfrdwinai,  tv  8e  T<f  virvip  ffvyK\eifTai ;  &s  8'  tu>  /urjSe  ave/j.01 
(3\dirTia(Tiv,  TiOfjAv  /SAe^xxptSas  f/j.(f>vffa.i'  oQpvfft  re  airoytiffiaffai  ra  virtp  TOIV  o^drcav,  us 
/njS'  6  eK  TTJS  Ketf>a,\TJs  iSpws  Kanovpyfi. 


32  TAESAL   CARTILAGES. 

The  skin  of  the  eyelids  is  remarkably  smooth  and  delicate, 
and  destitute  of  fat.  It  is  abundantly  supplied  with  sensory 
nerves  by  branches  of  the  fifth  pair — namely,  by  the  supra- 
orbital,  supra-trochlear,  infra-trochlear,  lachrymal,  and  infra-orbital 
nerves. 

The  orbicularis  palpebrarum  has  been  already  described  (p.  28). 
It  is  supplied  by  the  facial  nerve. 

The  levator  palpebrce  arises  from  the  lesser  wing  of  the  sphenoid 
above  the  optic  foramen,  gradually  becomes  broader,  and  termi- 
nates in  a  thin  aponeurosis,  which  unites  with  the  broad  tarsal 
ligament,  and  is  lost  on  the  upper  surface  of  the  superior  tarsal 
cartilage. 

TARSAL  CAR-  These   are   plates  of  dense   connective   tissue, 

TILAGES  AND  which  support    and   give    shape    to   the    eyelids. 

LIGAMENTS.  There  is  one  for  each  lid,  and  they  are  connected 

at  the  angles  (commissures  or  canthi)  of  the  lids  through  the  medium 
of  fibrous  tissue.  They  can  best  be  examined  by  everting  the  lids. 
Each  cartilage  resembles  its  lid  in  form.  The  upper  is  the  larger, 
is  broad  in  the  middle,  and  gradually  becomes  narrower  at  either 
end.  The  lower  is  nearly  of  uniform  breadth  throughout.  Both 
are  thicker  on  the  nasal  than  on  the  temporal  side.  They  are 
connected  to  the  margin  of  the  orbit,  and  maintained  in  position 
by  the  broad  tarsal  or  palpebral  ligament  •  this  is  a  continuation 
from  the  periosteum  of  the  orbit  to  the  tarsal  cartilage,  and  is 
denser  at  the  outer  part  of  the  orbit.  There  are  two  of  them — 
upper  and  lower — and  they  pass  to  each  cartilage  respectively. 
When  an  abscess  forms  in  the  connective  tissue  of  the  lids,  these 
ligaments  prevent  the  matter  from  making  its  way  into  the 
orbit. 

Each  tarsal  cartilage  is  attached  on  its  outer  side  to  the  malar 
bone  by  the  external  tarsal  ligament,  and  on  its  side  to  the  nasal 
process  of  the  superior  maxillary  by  the  tendo  palpebrarum  or  the 
internal  tarsal  ligament. 

The  free  or  ciliary  margin  is  straight,  and  is  the  thickest  part 
of  the  tarsal  cartilages.  It  is  generally  stated  that  the  inner  edge 
of  each  is  sloped  or  bevelled  off;  and  that,  when  the  lids  are 
closed,  there  is  formed,  with  the  globe  of  the  eye,  a  triangular 


PUNCTA   LACHRYMALIA.  33 

channel.  This  channel  is  said  to  conduct  the  tears  to  the  puncta 
lachrymalia.  According  to  our  observation,  this  channel  does  not 
exist ;  for  when  the  lids  are  closed,  their  margins  are  in  such 
accurate  apposition,  that  not  the  slightest  interspace  can  be  dis- 
covered between  them. 

PUNCTA  The  puncta  lachrymalia  are  two  pin-hole  aper- 

LACHBYMALIA.  tures,  easily  discovered  on  the  margin  of  the  lids, 

close  to  the  inner  angle.  They  are  the  orifices  of  the  canals,  called 
canaliculi,  which  pass  inwards,  and  convey  the  tears  into  the  lachry- 
mal sac.  Observe  that  their  orifices  are  directed  backwards.  The 
upper  canaliculus,  the  longer  and  narrower  of  the  two,  ascends  for 
a  short  distance  nearly  vertically,  and  then  dilating  into  a  small 
pouch  makes  a  sharp  bend  inwards  for  about  a  quarter  of  an  inch 
to  join  the  lachrymal  sac ;  the  lower  canal  descends  perpendicularly, 
and,  like  the  upper,  makes  a  sharp  bend,  after  which  it  pursues  a 
direction  upwards  and  inwards  to  the  sac.  The  two  canals  open 
separately  into  the  sac  (sometimes 
by  a  common  orifice).  In  facial 
palsy,  the  tensor  tarsi  being  affected, 
the  puncta  lose  their  proper  direc- 
tion, and  the  tears  flow  over  the 
cheek. 

In  the  introduction  of  probes 
for  the  purpose  of  opening  the  con- 
tracted puncta,  or  of  slitting  up  the 
lachrymal  ducts,  it  is  necessary  to 
know  the  exact  direction  of  these 
canals.  (See  diagram.)  When  from 
any  cause  the  tears  are  secreted  in  greater  quantity  than  usual, 
they  overflow  and  trickle  down  the  cheek. 

MEIBOMIAN  These  long  compound  sebaceous  glands,  so  called 

GLANDS.  after  the  anatomist J  who  first  described  them,  are 

situated  on  the  under  surface  of  each  of  the  tarsal  cartilages.  In 
the  upper  lid  there  are  between  twenty  and  thirty ;  not  quite  so 
many  in  the  lower.  On  everting  the  lid,  they  are  seen  running  in 
longitudinal  parallel  rows  in  grooves  in  the  cartilage.  Under  the 

1  H.  Meibom,  De  Vasis  Palpebrarum  novis.    Helmstedt,  1666. 

D 


.34  MUSCLES   OF   THE  NOSE. 

microscope,  each  is  seen  to  consist  of  a  straight  central  tube,  round 
the  sides  of  which  are  a  number  of  openings  leading  to  short  cascal 
dilatations.  The  orifices  of  these  glands  are  situated  on  the  free 
margin  of  the  lids  behind  the  lashes.  They  are  lined  with  flattened 
epithelial  cells  which,  in  the  cgecal  dilatations  and  ducts,  become 
cubical  and  filled  with  fat.  Their  function  is  to  secrete  a  sebaceous 
material,  which  prevents  the  lids  from  sticking  together. 

This  muscle  is  only  a  deeper  part  of  the  orbicu- 
laris  palpebrarum,  and  lies  just  behind  the  tendo 
palpebrarum.  To  expose  it,  cut  perpendicularly  through  the  middle 
of  the  upper  and  lower  lids,  and  turn  the  inner  halves  toward  the 
nose.  After  removing  the  mucous  membrane,  the  muscle  will  be 
seen  arising  from  the  ridge  of  the  lachrymal  bone.  It  passes  nearly 
horizontally  outwards,  for  about  three  lines,  and  then  divides  into 
two  portions,  which  are  inserted  into  the  upper  and  lower  tarsal 
cartilages,  close  to  the  orifices  of  the  lachrymal  ducts.  It  is  pro- 
bable that  the  tensor  tarsi  draws  backwards  the  open  mouths  of 
the  ducts,  so  that  they  may  receive  the  tears  at  the  inner  angle  of 
the  eye.  It  is  supplied  by  a  small  branch  from  the  facial  nerve. 

Let  us  now  examine  the  muscles  in  connection  with  the  nose : 
namely — the  pyramidalis  nasi,  the  compressor  naris,  the  depressor 
alas  nasi,  and  the  smaller  intrinsic  muscles  of  the  nose.  All  are 
supplied  by  the  facial  nerve. 

PYRAMIDALIS  This  is  situated  on  the  bridge  of  the  nose,  one 

NASI.  on  each  side  of  the  mesial  line,  and  is  usually 

regarded  as  a  continuation  of  the  inner  part  of  the  occipito-frontalis 
(p.  26).  The  two  muscles  diverge  as  they  descend,  and  their  fibres 
blend  with  those  of  the  compressor  naris.  Their  action  produces 
transverse  wrinkles  of  the  skin  at  the  root  of  the  nose,  as  in  the 
expression  of  an  aggressive  feeling. 

COMPRESSOR  This   muscle  is   triangular,  and   arises   by  its 

NARIS.  apex  from  the  inner  side  of  the  canine  fossa  of  the 

superior  maxilla,  and  is  attached  to  a  broad  thin  aponeurosis  which 
spreads  over  the  dorsum  of  the  nose,  and  joins  its  fellow.  The 
origin  of  this  muscle  is  concealed  by  the  levator  labii  superioris 
alaeque  nasi. 

When  this  muscle  is  reflected  from  its  junction  with  its  fellow, 


MUSCLES   OF   THE   NOSE   AND   LIP.  35 

a  small  nerve  is  seen  running  down  towards  the  tip  of  the  nose. 
This  nerve  is  the  superficial  branch  of  the  nasal  nerve  (called  also 
naso-lobular').  It  becomes  subcutaneous  between  the  nasal  bone 
and  the  cartilage,  and  supplies  the  tip  and  lobule  of  the  nose.  It 
is  joined  by  a  branch  of  the  facial  nerve  at  its  termination. 

DEPRESSOR  ALJE         This   arises  from  the    superior  maxilla,   above 
NASI.  the  second  incisor  tooth,  and  is  inserted  into  the 

septum  and  ala  of  the  nose.  It  is  situated  between  the  mucous 
membrane  and  the  muscular  structure  of  the  upper  lip ;  so  that, 
to  expose  it,  the  upper  lip  must  be  everted,  and  the  mucous  mem- 
brane removed. 

Besides  the  muscles  above  described,  we  find  in  connection  with 
the  cartilages  of  the  alas  of  the  nose,  pale  muscular  fibres  which 
have  no  very  definite  arrangement  and  require  a  lens  for  their 
detection.  The  dilatator  naris  posterior  arises  from  the  nasal  pro- 
cess of  the  superior  maxilla  and  the  sesamoid  cartilages,  and  is  in- 
serted into  the  skin  of  the  margin  of  the  nostril  j  the  dilatator 
naris  anterior,  descends  vertically  from  the  cartilage  of  the  aper- 
ture to  its  free  margin.  The  action  of  these  small  muscles  is  to 
raise  and  evert  the  ala  of  the  nose,  and  to  counteract  its  tendency 
to  be  closed  by  atmospheric  pressure.  In  dyspnoea,  and  in  certain 
mental  emotions,  they  contract  with  great  energy. 

LEVATOR  LABII  This  arises  from  the  nasal  process  of  the  supe- 

SUPERIORIS  rior  maxillary  bone  near  its  orbital  margin,  and 

AI^EQUE  NASI.  passing  downwards  divides  into  two  portions :  an 
inner  inserted  into  the  side  of  the  ala  of  the  nose  ;  an  outer,  into 
the  upper  lip,  where  its  fibres  blend  with  the  orbicularis  oris  and 
levator  labii  superioris.  It  acts  chiefly  in  expressing  the  smile  of 
derision.  Its  habitual  use  occasions  the  deep  furrow  which,  in  most 
faces,  runs  from  the  ala  of  the  nose  towards  the  corner  of  the  mouth. 

LEVATOR  LABII  This  arises  from  the  lower  margin  of  the  orbit, 

•SUPERIORIS  i.e.  from  the    superior  maxilla   and  malar  bone, 

PROPRIUS.  above  the  infra-orbital   foramen,   and  is  inserted 

into  the  upper  lip,  where  its  fibres  blend  with  the  orbicularis  oris. 
It  is  nearly  an  inch  in  breadth  at  its  origin,  which  covers  the 
infra-orbital  vessels  and  nerves,  and  is  itself  overlapped  by  the 
orbicularis  palpebrarum. 

D   2 


36  BUCCINATOR. 

LEVATOB  This  muscle,  which  is  covered  by  the  levator 

ANGULI  OBIS.  labii  superioris,  arises  from  the  canine  fossa  of  the 

superior  maxilla,  below  the  infra-orbital  foramen,  and  is  inserted 
into  the  angle  of  the  mouth,  superficial  to  the  buccinator,  its  fibres 
blending  with  those  of  the  orbicularis  oris,  the  zygomatici,  and  the 
depressor  anguli  oris. 

The  buccinator  arises  from  the  outer  surface  of 
the  alveolar  borders  of  the  upper  and  lower  jaws 
corresponding  to  the  molar  teeth,  and  behind  from  the  pterygo- 
maxillary  ligament.  The  fibres  pass  forwards  and  converge,  to  be 
inserted  into  the  angle  of  the  mouth  and  the  muscular  structure  of 
the  lips ;  the  central  fibres  decussate,  while  the  upper  fibres  pass 
to  the  upper  lip,  and  the  lower  fibres  pass  to  the  lower  lip.  The 
muscle  is  covered  on  its  inner  aspect  by  the  mucous  membrane  of 
the  cheek,  and  on  its  outer  by  a  thin  fascia  which  passes  backwards, 
and  is  continuous  with  that  covering  the  pharynx. 

The  buccinator  is  the  principal  muscle  of  the  cheek.  It  forms 
with  the  superior  constrictor  of  the  pharynx  a  continuous  muscular 
wall  for  the  side  of  the  mouth  and  pharynx.  The  bond  of  connec- 
tion between  the  buccinator  and  the  superior  constrictor  is  a  ten- 
dinous band,  the  pterycjo-maxillary  ligament.  This  ligament  (see 
diagram)  extends  from  the  hamular  process  vertically  to  the  poste- 
rior extremity  of  the  mylo-hyoid  ridge  of  the  lower  jaw  near  the 
last  molar  tooth.  It  is  simply  a  fibrous  intersection  between  the 
two  muscles. 

The  duct  of  the  parotid  gland  pierces  the  buccinator  obliquely, 
and  opens  into  the  mouth  opposite  the  second  molar  tooth  of  the 
upper  jaw. 

The  chief  use  of  the  buccinator  is  to  keep  the  food  between 
the  teeth  during  mastication.  It  can  also  widen  the  mouth.  Its 
power  of  expelling  air  from  the  mouth,  as  in  whistling  or  playing 
on  a  wind  instrument,  has  given  rise  to  its  peculiar  name.  It  is 
supplied  by  the  facial  nerve,  and  is,  therefore,  affected  in  facial 
paralysis. 

The  buccinator  is  in  relation,  externally  and  behind,  with  a 
large  amount  of  buccal  fat,  with  the  masseter  and  temporal  muscles  ; 
in  front  with  the  risorius,  the  levator  anguli  oris,  depressor  anguli 


BUCCAL   FASCIA. 


37 


oris,  the  zygomatici,  the  duct  of  the  parotid  gland,  the  facial 
artery  and  vein,  and  the  facial  and  buccal  nerves ;  internally  with 
the  mucous  membrane  of  the  mouth  and  buccal  glands ;  and  pos- 
teriorly with  the  pterygo-maxillary  ligament. 


FIG.  15. 

Tensor  palati. 
Levator  palati. 


Orbicularis  oris  .    . 

Pterygo-maxill  ary 
ligament    .    . 


Mylo-hyoideus    .    . 

Os  hyoides      .    .    .  _ 
Thyro-hyoid  liga-  1 
ment  .    .    .    .    / 

Pomum  Adami  .    . 


Cricoid  cartilage     . 
Trachea      .    .    .     . 


Glosso-pharyngeal  n. 
Stylo-pharyngeus. 


Superior  laryngeal 
n.  and  a. 


External  laryngeal  n. 
Crico-thyroideua. 

Inferior  laryngeal  n. 
CEsopliagus. 


MUSCLES   OF   THE   PHARYNX. 


BUCCAL  FASCIA. 


The  buccinator  muscle  is  covered  by  a  thin 
layer  of  fascia,  which  adheres  closely  to  its  surface, 
and  is  attached  to  the  alveolar  border  of  the  upper  and  lower  jaws. 
This  structure  is  thin  over  the  anterior  part  of  the  muscle,  but 
more  dense  behind,  where  it  is  continuous  with  the  aponeurosis  of 


88  FACIAL    AKTERY. 

the  pharynx.  It  is  called  the  bucco-pharyngeal  fascia,  since  it 
supports  and  strengthens  the  muscular  walls  of  these  cavities.  In 
consequence  of  the  density  of  this  fascia,  abscesses  do  not  readily 
burst  into  the  mouth  or  the  pharynx. 

BUCCAL  AND  The  luccal  glands,  in  structure  compound  race- 

MOLAR  GLANDS.  mose  like  the  salivary,  are  situated  between  the 
buccinator  and  the  mucous  membrane.  They  resemble  the  labial 
glands  found  beneath  the  mucous  membrane  of  the  lips,  though 
somewhat  smaller.  Three  or  four  other  glands,  about  the  size  of 
a  little  split  pea,  should  be  made  out,  as  they  lie  between  the 
masseter  and  buccinator:  these  are  the  molar  glands.  Their 
secretion,  said  to  be  mucous,  is  conveyed  to  the  mouth  by  separate 
ducts  near  the  last  molar  teeth. 

Between  the  buccinator  and  the  masseter,  there  is,  in  almost  all 
subjects,  an  accumulation  of  fat.  It  is  found,  beneath  the  zygoma 
especially,  in  large  round  masses,  and  may  be  turned  out  with  the 
handle  of  the  scalpel.  It  helps  to  fill  up  the  zygomatic  fossa,  and 
being  soft  and  elastic,  presents  no  obstacle  to  the  free  movements 
of  the  jaw.  Its  absorption  in  emaciated  individuals  occasions  the 
sinking  of  the  cheek. 

The  facial  (external  maxillary)  artery  is  the 
third  branch  of  the  external  carotid.  It  ascends 
tortuously  beneath  the  posterior  belly  of  the  digastricus  and  the 
stylo-hyoideus,  next  through  or  under  the  substance  of  the  sub- 
maxillary  gland ;  it  then  rests  upon  the  mylo-hyoideus,  and  sub- 
sequently mounts  over  the  base  of  the  jaw  at  the  anterior  edge  of 
the  masseter  muscle.  This  part  of  the  course  of  the  facial  will  be 
fully  examined  further  on  in  the  dissection  of  the  neck.  It  now 
ascends  tortuously  near  the  corner  of  the  mouth  and  the  ala  of  the 
nose,  towards  the  inner  angle  of  the  eye,  where,  much  diminished 
in  size,  it  inosculates  with  the  terminal  branch  of  the  ophthalmic,  a 
branch  of  the  internal  carotid.  In  the  first  part  of  its  course  on  the 
face,  the  artery  is  covered  by  the  platysma  and  the  deep  fascia ; 
above  the  corner  of  the  mouth  it  is  crossed  by  a  few  fibres  of  the 
risorius  and  the  zygomatici ;  still  higher  it  is  covered  by  some  of 
the  fibres  of  the  elevator  of  the  upper  lip.1  It  lies  successively 
1  Not  infrequently  the  artery  lies  superficial  to  this  muscle. 


FACIAL   ARTERY. 


39 


upon  the  buccinator,  levator  anguli  oris,  and  levator  labii  superioris 
alasque  nasi  muscles.  In  its  course  along  the  face  it  gives  off  the 
following  branches  : — 

FIG.  16. 


BKANCHES   OF   THE    EXTERNAL   CAROTID   ARTEEY. 


1.  External  carotid. 

2.  Lingual. 

3.  Facial. 

4.  Inferior  labial. 

5.  Inferior  coronary. 

6.  Superior  coronary. 


7.  Lateral  nasal. 

8.  Angular. 

9.  Superior  thyroid. 

10.  and  16.  Occipital. 

11.  Posterior  auricular. 

12.  Anterior  auricular. 

13.  Internal  maxillary. 


14.  Transverse  facial. 

15.  Middle  temporal. 

17.  Anterior  temporal. 

18.  Posterior  temporal. 

19.  Supra-orbital. 

20.  Frontal. 


a.  The  inferior  labial  artery  passes  inwards  under  the  depressor 
anguli  oris  and  inosculates  with  the  mental  branch  of  the  inferior  dental, 
the  inferior  coronary,  and  the  submental  arteries. 


40  FACIAL   ARTERY. 

b.  The  inferior  coronary  artery  comes  off  near  the  angle  of  the 
mouth,    either   directly    from    the    facial,   or  in   common   with   the 
superior  coronary.     It  runs  tortuously  along  the  lower  lip,  beneath  the 
depressor  anguli  oris  ;  it  then  pierces  the  orbicularis,  running  between 
this  muscle  and  the  mucous  membrane  of  the  lip.    It  inosculates  largely 
with  its  fellow,  the  inferior  labial  and  the  mental  arteries. 

c.  The  superior  coronary,  larger  than  the  preceding,  is  given  off 
beneath  the  zygomatici.     It  proceeds  along  the  upper  lip  close  to  the 
mucous  membrane,  and  inosculates  with  its  fellow ;   thus  is  formed 
round  the  mouth  a  complete  arterial  circle,  which  can  be  felt  pulsa- 
ting on  the  inner  side  of  the  lip,  near  the  free  border.     From  this 
circle  numerous  branches  pass  off  to  the  papillae  of  the  lips,  and  the 
labial  glands.     The  superior  coronary  gives  off  a  branch,  the  artery  of 
the  septum,  which  ascends  along  the  septum  to  the  apex  of  the  nose ; 
also  a  small  one  to  the  ala  nasi. 

d.  The  lateral  artery  of  the  nose,  a  branch  of  considerable  size,  arises 
opposite  the  ala  nasi,  ramifies  upon  the  external  surface  of  the  nose,  and 
inosculates  with  the  nasal  branch  of  the  ophthalmic  artery,  the  infra- 
orbital,  and  the  artery  of  the  septum. 

e.  The  angular  artery,  which  may  be  regarded  as  the  termination  of 
the  facial,  inosculates  on  the  inner  side  of  the  tendo  palpebrarum  with 
the  nasal  branch  of  the  ophthalmic  artery. 

The  facial  artery  supplies  numerous  branches  to  the  muscles  of 
the  face,  and  inosculates  with  the  transversalis  faciei,  infra-orbital, 
the  mental,  the  sublingual  branch  of  the  lingual,  the  nasal  branches 
of  the  internal  maxillary  and  the  ophthalmic,  the  ascending 
pharyngeal  and  descending  palatine  arteries. 

The  facial  artery  and  its  branches  are  surrounded  by  a  minute 
plexus  of  nerves  (nervi  molles),  invisible  to  the  naked  eye.  They 
are  derived  from  the  superior  cervical  ganglion  of  the  sympathetic, 
and  exert  a  powerful  influence  over  the  contraction  and  dilatation 
of  the  capillary  vessels,  and  thus  occasion  those  sudden  changes  in 
the  countenance  indicative  of  certain  mental  emotions,  e.g.1  blushing 
or  sudden  paleness.1 

The  facial  vein   does  not  run  with  the    artery,  but  takes  a 

1  MM.  Bernard  and  Brown-S6quard  have  proved  by  experiment,  that  if  the 
branches  of  the  sympathetic,  which  accompany  the  facial  artery,  be  divided,  the 
capillary  vessels  of  the  face,  being  deprived  of  their  contractile  power,  become 
immediately  distended  with  blood,  and  the  temperature  of  the  face  is  raised. 


PAROTID    GLAND.  41 

straight  course  from  the  inner  angle  of  the  eye  to  the  anterior 
border  of  the  masseter.  In  this  course  it  descends  upon  the 
levator  labii  superioris,  then  passes  beneath  the  zygomatic 
muscles,  over  the  termination  of  the  parotid  duct,  and  at  the 
anterior  border  of  the  masseter  passes  over  the  jaw,  behind  the 
facial  artery,  and  joins  the  internal  jugular. 

The  facial  vein  is  a  continuation  of  the  frontal,  which  descends 
over  the  forehead,  and,  after  receiving  the  supra-orbital,  takes  the 
name  of  angular  at  the  corner  of  the  eye.  It  communicates  with 
the  ophthalmic  vein,  receives  the  veins  of  the  eyelids,  the  external 
part  of  the  nose,  the  coronary  veins,  and  others  from  the  muscles 
of  the  face.  Near  the  angle  of  the  mouth  it  is  increased  in  size 
by  a  communicating  branch  from  the  infra-orbital  vein,  and  by  a 
large  vein  which  comes  from  the  temporo-maxillary  vein.  The  other 
veins  which  empty  themselves  into  the  facial  correspond  with  the 
branches  given  off  from  the  facial  artery. 

ARTEKIA  This  artery  arises  from  the  temporal,  or  occa- 

TEANSVEESALIS  sionally  from  the  external  carotid  in  the  substance 
FACIEI-  of  the  parotid  gland.  It  runs  forwards  across  the 

masseter  between  the  parotid  duct  and  the  zygoma,  and  is  dis- 
tributed to  the  glandula  socia  parotidis,  and  the  masseter.  It 
anastomoses  with  the  infra-orbital,  buccal  and  facial.  It  is  seldom 
of  large  size,  except  when  it  supplies  those  parts  which  usually 
receive  blood  from  the  facial.  We  have  seen  it  as  large  as  a  goose- 
quill,  furnishing  the  coronary  and  the  nasal  arteries  ;  the  facial 
itself  not  being  larger  than  a  sewing  thread. 

The  parotid  gland  is  now  to  be  examined.  Its  boundaries,  its 
deep  relations,  the  course  of  its  duct,  and  the  objects  contained 
within  the  gland,  must  be  carefully  observed. 

PAROTID  The  parotid,1  the  largest  of  the  salivary  glands, 

GLAND.  occupies  the  space  between  the  ramus  of  the  jaw 

and  the  mastoid  process,  and  weighs  between  five  and  eight  drachms. 
It  is  bounded  above  by  the  zygoma ;  below,  by  the  sterno-mastoid 
and  digastric  muscles ;  behind,  by  the  meatus  auditorius  externus 
and  the  mastoid  process;  in  front,  it  lies  over  the  ascending  ramus 
of  the  jaw,  and  is  prolonged  for  some  distance  over  the  masseter. 
1  From  iropa,  near  ;  oSs,  the  ear. 


42  PAROTID    GLAND. 

It  is  separated  from  the  submaxillary  gland  by  the  stylo-maxillary 
ligament ;  sometimes  the  two  glands  are  directly  continuous. 

The  superficial  surface  of  the  gland  is  flat,  and  covered  by  a 
strong  layer  of  fascia,  a  continuation  of  the  cervical,  and  has  one 
or  two  lymphatic  glands  lying  on  it.  It  not  only  surrounds  the 
gland,  but  sends  down  numerous  partitions  which  form  a  frame- 
work for  its  lobes.  The  density  of  this  sheath  explains  the  pain 
caused  by  inflammation  of  the  gland,  the  tardiness  with  which 
abscesses  within  it  make  their  way  to  the  surface,  and  the  propriety 
of  an  early  opening. 

The  deep  surface  of  the  gland  is  irregular,  and  moulded  upon 
the  subjacent  parts.  Thus  it  sends  a  prolongation  which  passes 
inwards  between  the  neck  of  the  jaw  and  the  internal  lateral  liga- 
ment ;  another  process  which  passes  in  front  of  the  styloid 
process,  and  extends  upwards  and  occupies  the  posterior  part  of 
the  glenoid  cavity ;  a  third  process  passes  behind  the  styloid 
process,  below  the  mastoid  process  and  behind  the  sterno-mastoid 
muscle,  and  sometimes  penetrates  deep  enough  to  be  in  contact 
with  the  internal  jugular  vein. 

The  internal  carotid  artery  and  internal  jugular  vein  are  in 
contact  with  the  gland  behind. 

On  carefully  removing  the  substance  of  the  parotid  gland,  the 
following  structures  are  seen  in  its  interior,  proceeding  in  the  order 
of  their  depth  from  the  surface  : 

1.  Two  or  more  small  lymphatic  glands. 

2.  The  pes  anserinus,  or  primary  branches  of  the  facial  nerver 
which  emerge  at  its  anterior  border. 

3.  Branches   from  the  great  auricular   and  auriculo-temporal 
nerves  which  communicate  in  its  substance  with  the  facial  nerve. 

4.  The  external  jugular  vein  formed  by  the  junction   of  the 
internal  maxillary  and  temporal  veins. 

5.  The  external  carotid  artery,  which,  after  distributing  many 
branches  to  the  gland,  divides,  opposite  the  neck  of  the  jaw,  into 
the  internal  maxillary  and  temporal ;  the  latter  giving  off  in  the 
gland  the  posterior  auricular  and  transverse  facial  arteries.1 

1  Keviewing  the  intimate  and  deep  connections  of  the  parotid  gland,  one  cannot 
but  conclude  that  it  is  almost  impracticable  to  remove  it  entirely  during  life.  If 


PAROTID    GLAND.  43 

That  portion  of  the  gland  which  lies  on  the  masseter  muscle  is 
called  glandula  soda  parotidis.  It  varies  in  size  in  different 
subjects  ;  and  is  situated  chiefly  above  the  parotid  duct,  into  which 
it  pours  its  secretion  by  one  or  two  smaller  ducts. 

The  duct  of  the  parotid  gland  (ductus  Stenonis  !),  about  two 
inches  and  a  half  long,  is  very  thick  and  strong.  In  this  respect 
it  differs  from  the  duct  of  the  submaxillary  gland,  which  is  less 
exposed  to  injury.  It  runs  transversely  forwards  over  the  mas- 
seter, about  an  inch  below  the  zygoma,  through  the  fat  of  the 
cheek,  then  perforates  the  buccinator  obliquely,  and  opens  into 
the  mouth  opposite  the  second  molar  tooth  of  the  upper  jaw. 
Near  its  termination  it  is  crossed  by  the  zygomaticus  major  and 
the  facial  vein.  After  perforating  the  buccinator,  the  duct  passes 
for  a  short  distance  between  the  muscle  and  the  mucous  membrane. 
Its  orifice  is  small  and  contracted  compared  with  the  diameter  of 
the  rest  of  the  duct,  which  will  admit  a  crow-quill ;  it  is  not  easily 
found  in  the  mouth,  being  concealed  by  a  fold  of  mucous  membrane. 

The  direction  of  the  parotid  duct  corresponds  with  a  line  drawn 
from  the  middle  of  the  lobule  of  the  ear  to  a  point  midway  between 
the  nose  and  the  mouth. 

The  blood  supply  of  the  parotid  is  derived  from  the  external 
carotid  and  its  branches,  which  are  accompanied  by  their  respective 
veins.  Its  nerves  are  supplied  from  the  sympathetic  plexus  around 
the  external  carotid,  the  auriculo-temporal,  the  great  auricular  and 
the  facial  nerves. 

The  lymphatic  glands  about  the  parotid  deserve  notice,  since 
they  are  liable  to  become  enlarged,  and  simulate  disease  of  the 
parotid  itself.  A  lymphatic  gland  lies  close  to  the  root  of  the 
zygoma,  in  front  of  the  cartilage  of  the  ear ;  this  gland  is  some- 
times affected  in  disease  of  the  external  tunics  of  the  eye ;  e.g.  in 
purulent  ophthalmia  :  also  in  affections  of  the  scalp. 

this  conclusion  be  correct,  even  in  the  normal  condition  of  the  gland,  what  must 
it  be  when  the  gland  is  enlarged  by  disease  ?  John  Bell,  however,  relates  a  case 
in  which  he  was  induced  to  attempt  the  extirpation  of  a  diseased  parotid  (Principles 
of  Surgery,  vol.  iii.  p.  262).  Other  surgeons,  too,  of  more  modern  date,  have 
attempted  the  same  thing.  It  is  not  unlikely  that  they  have  mistaken  a  tumour 
in  the  substance  of  the  parotid  for  disease  of  the  parotid  itself. 
1  Nic.  Steno,  De  Glandulis  Oris,  etc.  Bat.  1661. 


44  THE   FACIAL   NERVE. 

The  parotid  belongs  to  the  compound  racemose  form  of  glands. 
Tracing  its  main  duct  into  the  substance  of  the  gland,  we  find  that 
it  divides  into  smaller  ones,  which  again  divide  into  the  smaller 
ramuscules  which  open  into  caecal  dilatations  called  alveoli.  Each 
alveolus — about  12*00  of  an  inch  in  diameter — has  a  more  or  less 
defined  basement  membrane  upon  which  the  cells  rest.  The  cells 
are  flattened  and  spheroidal,  enclosing  nuclei,  some  of  them  having 
outstanding  processes  from  the  bases  of  the  cells.  An  aggregation 
of  these  alveoli  forms  a  small  lobule,  from  which  a  small  excretory 
duct  proceeds ;  these  lobules  are  united  by  intervening  connective 
tissue,  which  is  a  continuation  inwards  of  the  dense  fascia  covering 
the  gland.  The  connective  tissue  varies  much  in  thickness  in 
different  situations,  and  where  it  is  most  abundant  it  is  distinctly 
lamellar  (Klein),1  and  contains  numerous  granular  plasma  cells 
and  lymphoid  tissue.  The  small  ramuscules  have  only  a  basement 
membrane  with  flattened  cells,  which  change  in  the  smaller  ducts 
to  a  columnar  form,  while  in  the  larger  ducts  the  epithelium  is 
squamous. 

The  parotid  gland  secretes  an  alkaline  watery  fluid,  containing 
solids  which  amount  to  6  parts  in  1,000.  The  solids  consist  of 
ptyalin,  a  special  ferment,  mucus,  and  certain  salts,  chiefly  sulpho- 
cyanide  of  potassium,  chlorides  and  phosphates  of  potassium, 
sodium,  lime,  and  magnesia.  Apart  from  its  mechanical  proper- 
ties, the  parotid  secretion  has  the  power,  by  means  of  its  ptyalin, 
of  converting  starch  into  dextrine  and  grape  sugar. 

To  display  the  plexus  of  nerves  (pes  anserinus),  formed  by  the 
branches  of  the  facial,  cut  into  the  parotid  gland  by  a  vertical 
incision  until  the  main  trunk  of  the  nerve  is  reached. 

POBTIO  DURA,  This  is  the  seventh  cranial  nerve,  and  is  the 

OB  FACIAL  NERVE,  motor  nerve  of  the  face.  It  supplies  all  the 
muscles  of  expression,  the  platysma,  and  the  buccinator.  Through 
some  of  its  branches  it  supplies  other  muscles,  the  description  of 
which  will  be  deferred  till  the  facial  nerve  is  dissected  in  the  tem- 
poral bone.  It  arises  immediately  below  the  pons  Varolii,  from 
the  lateral  tract  of  the  medulla  oblongata,  between  the  olivary  and 
restiform  bodies.  The  nerve  enters  the  meatus  auditorius  internus, 
1  Klein,  Quarterly  Journal  of  Microscopical  Science,  1882. 


THE   FACIAL   NERVE.  45 

lying  upon  the  auditory  nerve,  traverses  a  tortuous  bony  canal 
(aqueductus  Fallopii)  in  the  petrous  portion  of  the  temporal  boner 
and  leaves  the  skull  at  the  stylo-mastoid  foramen.  Its  course  and 
connections  in  the  temporal  bone  will  be  studied  hereafter :  at 
present  we  must  trace  the  facial  part  of  the  nerve. 

Having  emerged  from  the  stylo-mastoid  foramen,  the  nerve 
enters  the  parotid  gland,  and  divides  behind  the  ramus  of  the  jaw 
into  two  primary  branches,  named,  from  their  distribution,  temporo- 
facial  and  cervico-facial.  These  primary  branches  cross  over  the 
external  carotid  artery  and  the  external  jugular  vein,  and  form,  by 
their  communications  within  the  substance  of  the  parotid,  the  plexus 
called  pes  anserinus,  from  its  fancied  resemblance  to  the  skeleton  of 
a  goose's  foot.  (Diagram,  p.  46.) 

Close  to  the  stylo-mastoid  foramen,  the  facial  nerve  gives  off 
its  'posterior  auricular  branch  (p.  6),  which  ascends  behind  the  ear 
and  divides  into  two,  an  auricular  and  an  occipital ;  the  former 
supplies  the  retrahens  and  attollens  aurem,  the  latter  the  posterior 
belly  of  the  occipito-frontalis.  This  branch  communicates  with  the 
deep  branch  of  the  great  auricular  n.,  with  the  small  occipital,  and 
with  the  auricular  branch  of  the  pneumogastric.  Its  two  next 
branches  supply  the  stylo-hyoideus  and  the  posterior  belly  of  the 
digastricus.  The  digastric  nerve  enters  the  muscle  by  many  fila- 
ments ;  the  nerve  to  the  stylo-hyoid  is  long  and  enters  the  muscle 
about  the  middle.  The  stylo-hyoid  branch  communicates  with 
the  sympathetic  on  the  external  carotid  a. ;  the  digastric  branch 
with  the  glosso-pharyngeal  near  the  base  of  the  skull.  These  two 
muscular  nerves  are  frequently  given  off  from  a  common  branch. 

The  temporo-facial  division,  the  larger  of  the  two,  in  passing 
through  the  parotid  gland,  crosses  the  external  carotid  and  the 
neck  of  the  jaw,  receives  two  or  more  communications  from  the 
auriculo-temporal  (branch  of  the  fifth)  and  subdivides  into  temporal, 
malar,  and  infra-orbital  branches. 

The  temporal  branches  ascend  over  the  zygoma,  supply  the  frontalis, 
the  attrahens  aurem,  the  orbicularis  palpebrarum,  the  corrugator  super- 
cilii,  and  tensor  tarsi,  and  communicate  with  filaments  of  the  supra- 
orbital  nerve,  with  the  temporal  branch  of  the  superior  maxillary  n., 
with  the  auriculo-temporal  n.,  and  with  the  lachrymal  n. 


46  THE   FACIAL   NERVE. 

The  malar  branches  cross  the  malar  bone,  supply  the  orbicular 
muscle,  and  communicate  with  filaments  of  the  lachrymal,  the  supra- 
orbital,  the  superior  maxillary,  and  the  malar  branch  of  the  superior 
maxillary. 

FIG.  17. 


DIAGRAM   OF   THE   BBANCHES   OF   THE    FACIAL   NERVE. 

1.  Branch  to  occipito-froutalis.  5.  Infra-orbital. 

2.  Posterior  auricular.  6.  Buccal. 

3.  Temporal  brandies.  7.  Supra-maxillary. 

4.  Malar  branches.  8.  Infea-maxillary. 

The  infra-orbital  branches  are  the  largest,  and  proceed  transversely 
forwards  over  the  masseter  beneath  the  zygomatici,  to  supply  the  orbi- 
cularis  oris,  the  elevators  of  the  upper  lip,  and  the  muscles  of  the  nose. 
The  superficial  branches  join  with  the  nasal  and  infra-trochlear  branches 
of  the  ophthalmic  along  the  side  of  the  nose  ;  the  deep  branches  com- 
municate beneath  the  levator  labii  superioris  with  the  infra-orbital 
branches  of  the  superior  maxillary  nerve  forming  the  infra-orbital 
plextis,  and  also  with  the  buccal  branches  of  the  facial. 

The  cervico-facial  division,  joined  in  the  parotid  gland  by  fila- 
ments from  the  great  auricular  (branch  of  the  cervical  plexus), 
descends  towards  the  angle  of  the  jaw,  and  subdivides  into  buccal, 
supra-  and  infra-maxillary  branches. 


SENSORY   NERVES    OF  THE   FACE.  47 

The  buccal  branches  pass  forwards  over  the  masseter  parallel  with 
the  parotid  duct,  and  supply  the  buccinator  :  they  communicate  with 
the  buccal  branch  of  the  inferior  maxillary  nerve  (third  division  of  the 
fifth),  and  with  the  infra-orbital  nerve. 

The  supra-maxillary  branches  advance  over  the  masseter  and  facial 
artery,  and  run  under  the  platysma  and  the  depressor  muscles  of  the 
lower  lip,  all  of  which  they  supply.  Some  of  the  filaments  communicate 
with  the  mental  branch  of  the  inferior  dental  nerve. 

The  infra-maxillary  or  cervical  branches,  one  or  more  in  number 
arch  forwards  below  the  jaw  covered  by  the  platysma,  as  low  as  the 
hyoid  bone,  and  communicate  with  the  superficial  cervical  (branch  of 
the  cervical  plexus). 

SENSORY  NERVES        These  are  the  supra-orbital,  the  supra-  and  infra- 
OF  THE  FACE.  trochlear,  the  naso-lobular,  the  temporo-malar,  the 

infra-orbital,  and  the  mental,  all  branches  of  the  fifth  pair. 

The  supra-orbital  nerve  is  the  continuation  of  the  frontal,  which 
is  a  branch  of  the  first  division  of  the  fifth  pair.  It  leaves  the 
orbit  through  the  supra-orbital  notch  and  ascends  upon  the  fore- 
head, at  first  covered  by  the  orbicularis  and  occipito-frontalis.  It 
presently  divides  into  two  sets  of  branches — an  outer,  the  larger, 
which  passes  backwards  as  far  as  the  occipital  bone,  and  an  inner, 
which  ascends  as  far  as  the  parietal  bone.  It  distributes  sensory 
muscular  branches  also  to  the  orbicularis  palpebrarurn,  corrugator 
supercilii,  the  occipito-frontalis,  to  the  pericranium  and  branches 
which  supply  the  skin  of  the  forehead,  upper  eyelid,  and  scalp.  It 
communicates  with  the  facial  nerve  on  the  forehead.  The  supra- 
orbital  artery  is  a  branch  of  the  ophthalmic. 

The  supra-trochlear  n.,  or  internal  frontal,  appears  at  the  inner 
angle  of  the  orbit  between  the  supra-orbital  foramen  and  the  pulley 
of  the  superior  oblique,  and  sends  down  in  front  of  the  pulley  a  loop 
to  communicate  with  the  infra-trochlear  branch  of  the  nasal.  The 
main  trunk  of  the  nerve  ascends  to  the  forehead.  Its  further 
course  has  been  described  (p.  5). 

The  infra-trochlear  n.  issues  from  the  orbit  below  the  pulley, 
and  supplies  branches  to  the  eyelids,  the  conjunctiva,  lachrymal 
sac,  and  the  side  of  the  nose. 

The  infra-orbital  nerve  is  the  terminal  branch  of  the  superior 


48 


SENSORY   NERVES   OF   THE   FACE. 


maxillary  or  second  division  of  the  fifth  nerve.  It  emerges  with 
its  artery  from  the  infra-orbital  foramen,  covered  by  the  levator 
labii  superioris.  The  nerve  immediately  divides  into  several 


FIG.  18. 


DIAGRAM   OF   THE    SENSORY   NERVES   OF   THE    SCALP   AND   FACE. 


1.  Great  occipital. 

2.  Small  occipital. 

3.  Auricular  br.  of  the  pneumogastric. 

4.  Great  auricular. 

5.  Auriculo-temporal. 

6.  Temporal  br.  of  superior  maxillary  nerve. 

7.  Supra-orbital. 


8.  Supra-trochlear. 

9.  Malar  br.  of  superior  maxillary  nerve. 

10.  Infra-trochlear. 

11.  Kaso-lobular. 

12.  Infra-orbital. 

13.  Buccal  br.  of  inferior  maxillary  nerve. 

14.  Mental. 


branches,  palpebral,  nasal,  and  labial ;  the  palpebral,  ascending  be- 
neath the  orbicularis,  supply  the  lower  eyelid,  and  communicate 
with  the  facial  and  the  malar  branch  of  the  orbital  nerve ;  the 
nasal  pass  inwards  to  supply  the  nose,  and  join  the  nasal  branch 
(naso-lobular)  of  the  ophthalmic  ;  the  labial,  by  far  the  most  nume- 
rous, descend  into  the  upper  lip,  beneath  the  levator  labii  superioris, 
and  eventually  terminate  in  lashes  of  filaments,  which  endow  the 
papillse  of  the  lip  and  the  mucous  membrane  of  the  mouth  with 
exquisite  sensibility.  Close  to  the  infra-orbital  foramen  is  the 
infra-orbital  plexus,  before  alluded  to  (p.  46). 


DISSECTION    OF   THE    ORBIT.  49 

The  infra-orbital  artery  is  the  terminal  branch  of  the  internal 
maxillary  ;  it  supplies  the  muscles,  the  skin,  and  the  front  teeth  of 
the  upper  jaw,  and  inosculates  with  the  transverse  facial,  buccal, 
facial,  and  coronary  arteries. 

The  naso-lobular  nerce  is  the  external  branch  of  the  nasal  nerve 
and  is  distributed  to  the  tip  and  lobule  of  the  nose,  and  is  joined 
by  filaments  from  the  facial  nerve. 

The  temporal  branch  of  the  orbital  nerve  (branch  of  the  superior 
maxillary  nerve,  running  along  the  outer  wall  of  the  orbit,  and 
which  divides  into  a  temporal  and  a  malar  branch)  issues  through 
the  temporal  fascia  about  a  finger's  breadth  above  the  zygoma, 
and  supplies  the  skin  of  the  temple.  It  communicates  with  the 
facial  and  the  auriculo-temporal  nerves. 

The  malar  nerve,  a  branch  also  of  the  orbital  nerve,  issues 
through  a  foramen  in  the  malar  bone,  and,  after  piercing  the  orbi- 
cularis  palpebrarum,  supplies  the  skin  of  the  cheek  over  the  malar 
bone.  It  communicates  with  the  facial  and  the  palpebral  branches 
of  the  infra-orbital  nerve. 

The  mental  nerve  is  a  branch  of  the  inferior  maxillary  or  third 
division  of  the  fifth.  It  emerges  from  the  mental  foramen  in  the 
lower  jaw,  in  a  direction  upwards  and  backwards,  beneath  the 
depressor  anguli  oris.  It  soon  divides  into  a  number  of  branches 
beneath  the  depressor  labii  inferioris,  some  of  which  supply  the  skin 
of  the  chin,  but  the  greater  number  terminate  in  the  papillee  of  the 
lower  lip.  It  communicates  with  the  facial  nerve. 

The  mental  artery  is  a  branch  of  the  inferior  dental.  It  supplies 
the  gums  and  the  chin,  and  inosculates  with  the  sub-mental,  the 
inferior  labial,  and  inferior  coronary  arteries. 

_,  To  expose  the  contents  of  the  orbit,  remove  that 

DISSECTION.  .          „    ,  .  .  , 

portion  of  the  orbital  plate,  which  forms  the  roof 

of  the  orbit,  as  far  back  as  the  optic  foramen,  making  one  section 
with  a  saw  on  the  outer  side,  the  other  on  the  inner  side  of  the 
roof,  so  that  the  two  sections  converge  at  the  optic  foramen.  In 
doing  this,  be  careful  not  to  injure  the  little  pulley  on  the  inner 
side  for  the  superior  oblique.  If  the  bone  be  sufficiently  sawn 
through,  a  gentle  tap  with  the  saw  on  the  front  of  the  orbital  plate 
will  fracture  its  thin  wall  transversely.  The  anterior  fourth  of  the 


50 


DISSECTION   OF   THE   ORBIT. 


roof  should  be  turned  forwards  and  downwards  and  kept  in  this 
position  by  hooks ;  the  remainder  is  to  be  removed  by  bone  forceps 
nearly  as  far  as  the  optic  foramen,  so  as  to  leave  a  ring  of  bone 
from  which  most  of  the  ocular  muscles  have  their  origin.  The 
eyeball  should  be  made  tense  by  blowing  air  through  a  blowpipe 
passed  well  into  the  globe  through  the  cranial  end  of  the  optic 
nerve. 

PERIOSTEUM  OF          The  roof  being  removed  we  expose  the  fibrous 
THE  ORBIT.  membrane  which  lines  the  walls  of  the  orbit.     It 

is  a  continuation  of  the  dura  mater  through  the  sphenoidal  fissure. 
Traced  forwards,  we  find  that  it  is  loosely  connected  to  the  walls  of 
the  orbit,  and  that  at  the  margin  of  the  orbit  it  divides  into  two 
layers,  one  of  which  is  continuous  with  the  periosteum  of  the  fore- 
head, the  other  forms  the  broad  tarsal  ligament  which  fixes  the 
tarsal  cartilage. 

The  periosteum  is  now  to  be  removed,  and  the  fascia  of  the 
orbit  made  out.     The  following  objects  should  then  be  carefully 


DIAGRAM    Otf    THE    NERVES    01?    THE    ORBIT. 


traced  :  in  the  middle  are  seen  the  frontal  artery  and  nerve,  lying 
on  the  levator  palpebrae ;  on  the  outer  side,  the  lachrymal  nerve 
and  artery  pass  forwards  on  the  external  rectus  to  the  lachrymal 
gland,  which  lies  under  cover  of  the  external  angular  process  ;  on 


CONTENTS    OF   THE    ORBIT.  51 

the  inner  side  is  the  fourth  nerve,  lying  on  and  supplying  the 
superior  oblique. 

FASCIA  OF  THE  The  fascia  of  the    orbit  provides   the   lachry- 

OKBIT  AND  CAPSULE  mal  gland  and  each  of  the  muscles  with  a  loose 
OF  TENON.  sheath,  thin  and  delicate  at  the  back  of  the  orbit, 

but  stronger  near  the  eyeball.  It  is  pierced  behind  by  the  optic 
nerve  and  by  the  arteries  and  nerves  of  the  orbit,  while  in  front  it  is 
connected  with  the  ocular  conjunctiva  close  to  the  cornea.  The 
sheaths  are  firmly  adherent  to  the  muscles,  and  their  tendinous  in- 
sertions into  the  globe  are  connected  by  the  fascia.  From  the  in- 
sertions of  the  muscles  it  is  reflected  as  a  double  layer  backwards 
over  the  globe,  so  that  it  resembles  a  serous  membranous  sac — a 
tunica  vaginalis — one  layer  being  loosely  connected  with  the 
globe,  the  other  lining  the  fat  in  which  the  globe  is  set.  These 
layers  are  lined  with  epithelium,  and  are  separated  by  an  external 
lymph  space.  This  reflection  of  the  orbital  fascia  is  called  the 
capsule  of  Tenon,  its  use  being  to  allow  free  movement  of  the 
globe. 

The  orbit  contains  a  large  quantity  of  granular  fat,  which 
forms  a  soft  bed  for  the  eye,  and  prevents  its  being  retracted  too 
far  by  its  muscles.  Upon  the  amount  of  this  fat  depends,  in  some 
measure,  the  prominence  of  the  eyes.  Its  absorption  in  disease  or 
old  age  occasions  the  sinking  of  the  eyeballs. 

CONTENTS  OF  In  the  middle  of  the  orbit  is  the  eyeball,  sur- 

ras ORBIT.  rounded  by  more  or  less  fat,  and  attached  to  it  are 

six  muscles  which  move  it :  four,  running  forwards  in  a  straight 
direction,  are  called  the  recti,  and  are  arranged  one  above,  one  below, 
and  one  on  each  side  of  the  globe ;  the  remaining  two  are  called, 
from  their  direction,  obliqui,  one  superior,  the  other  inferior.  There 
is  also  a  muscle  to  raise  the  upper  eyelid,  termed  levator  palpetoce. 
The  nerves  are  :  the  optic,  which  passes  through  the  optic  foramen ; 
the  third,  the  fourth,  the  first  division  of  -the  fifth,  the  sixth,  and 
some  filaments  of  the  sympathetic,  all  of  which  pass  through  the 
sphenoidal  fissure.  The  third  supplies  all  the  muscles  with  motor 
power,  except  the  superior  oblique,  which  is  supplied  by  the  fourth, 
and  the  external  rectus,  which  is  supplied  by  the  sixth.  The  first 
or  ophthalmic  division  of  the  fifth  divides  into  a  frontal,  lachrymal, 

E   2 


52  FRONTAL  NERVE. 

and  nasal  branch.  The  ophthalmic  artery,  a  branch  of  the  internal 
carotid,  passes  into  the  orbit  through  the  optic  foramen  ;  its  vein 
passes  backwards  through  the  sphenoidal  fissure  to  join  the  cavern- 
ous sinus. 

The  ophthalmic,  or  first  division  of  the  fifth — 
a  sensory  nerve — after  giving  off  from  its  inner 
and  lower  side,  whilst  within  the  cavernous  sinus,  the  nasal  nerve, 
divides  into  the  frontal  and  lachrymal  nerves,  of  which  the  former 
is  the  larger.  It  is  the  smallest  division  of  the  fifth,  and  runs  for- 
wards for  the  distance  of  about  an  inch  ;  in  its  course  it  is  con- 
nected with  the  cavernous  plexus  of  the  sympathetic,  with  the 
third,  fourth,  and  sixth  nerves,  and  close  to  its  origin  from  the 
Gasserian  ganglion  it  sends  off  a  small  recurrent  branch  to  the  ten- 
torium  cerebelli.  One  of  its  divisions,  the  frontal  nerve,  runs  for- 
wards upon  the  upper  surface  of  the  levator  palpebrse,  on  which, 
about  midway  in  the  orbit,  it  divides  into  two  branches — the  supra- 
trochlear  and  the  supra-orbital. 

FIG.  20. 

IN  FRA-TROCHLEAR 


SUPRA-ORBITAl. 


TROCHLE  AR 


OPTIC 
VIEW   OF   DEBIT   FROM   ABOVE. 


«.  The  snpra-trochlear,  the  smaller  of  the  two  (fig.  20)  runs  obliquely 
inwards  above  the  pulley  of  the  superior  oblique  to  the  inner  angle  of 
the  orbit.  Here  it  gives  off  a  'small  communication  downwards  to  the 


LACHRYMAL   GLAND.  53 

infra-trochlear  branch  of  the  nasal,  and  then  divides,  after  passing 
between  the  bone  and  the  orbicularis  palpebrarum,  into  filaments  which 
supply  the  skin  of  the  upper  eyelid,  forehead,  and  nose.  One  or  two 
small  filaments  may  be  traced  through  the  bone  to  the  mucous  mem- 
brane of  the  frontal  sinuses.1 

b.  The  supra-orbital  is  the  continuation  of  the  frontal  nerve,  and 
runs  forwards  011  the  levator  palpebrse  to  the  supra-orbital  notch, 
through  which  it  ascends  to  supply  the  skin  of  the  upper  eyelid,  fore- 
head, pericranium,  and  scalp.  Its  cutaneous  branches,  an  inner  and  an 
outer,  which  run  upwards  beneath-  the  occipito-frontalis,  have  been 
described  in  the  dissection  of  the  scalp  (p.  5).  It  supplies  with  common 
sensation  the  orbicularis  palpebrarum,  the  occipito-frontalis,  and  the 
corrugator  supercilii,  where  it  joins  the  facial  nerve. 

LACHRYMAL  This  is  the  smallest  of  the  three  branches  of  the 

NERVE.  ophthalmic  nerve.  It  runs  along  the  upper  border 

of  the  external  rectus  011  the  outer  side  of  the  orbit  with  the 
lachrymal  artery,  through  the  lachrymal  gland,  which  it  supplies 
as  well  as  the  upper  eyelid.  Its  branches  within  the  orbit  are :  1,  a 
branch  which  passes  down  behind  the  lachrymal  gland  to  communi- 
cate with  the  orbital  branch  of  the  superior  maxillary  nerve ;  2. 
filaments  to  the  lachrymal  gland.  It  then  pierces  the  palpebral 
ligament  to  supply  the  skin  of  the  upper  eyelid. 

FOURTH  CRA-  This  nerve  enters  the  orbit  through  the  sphe- 

NIAL  NERVE.  noidal  fissure  above  the  other  nerves.  It  runs 

along  the  inner  side  of  the  frontal  nerve,  and  enters  the  upper  or 
orbital  surface  of  the  superior  oblique,  to  which  it  is  solely  distri- 
buted. This  nerve  is  joined  in  the  outer  wall  of  the  cavern- 
ous sinus  by  filaments  from  the  sympathetic.  It  communicates 
occasionally  with  the  lachrymal,  and  the  ophthalmic  division  of 
the  fifth.  Here  also  it  sends  backwards  two  or  more  filaments  to 
supply  the  tentorium  cerebelli. 

LACHRYMAL  This  gland  is  situated  below  the  external 

GLAND.  angular  process  of  the  frontal  bone.  It  is  about 

the  size  and  shape  of  an  almond.  Its  upper  surface  is  convex,  in 
adaptation  to  the  roof  of  the  orbit ;  its  lower  is  concave,  in  adap- 
tation to  the  eyeball,  and  rests  upon  the  external  and  superior 

1  These  filaments  have  been  described  by  Blumenbach,  De  Sinibus  Frontalibus. 


54 


MUSCLES   OF   THE   ORBIT. 


FIG.  21. 


rectus.  The  anterior  part  of  the  gland  lies  sometimes  separated 
from  the  rest,  close  to  the  back  part  of  the  upper  eyelid,  and  is 
covered  by  the  conjunctiva.  The  gland  is  invested  by  a  capsule  ' 
formed  by  the  fascia  of  the  orbit. 

The  lachrymal  gland  consists  of  an  aggregation  of  small  lobes 
composed  of  smaller  lobules,  connected  by  fibro-cellular  tissue,  and 

resembles  the  structure  of  the  sali- 
vary glands.  The  excretory  ducts, 
seven  to  ten  in  number,  run  parallel, 
and  perforate  the  conjunctiva  in  a 
row,  about  a  quarter  of  an  inch 
above  the  edge  of  the  tarsal  cartilage 
(fig.  21).  They  are  not  easily  dis- 
covered in  the  human  eye  ;  in  that 
of  the  horse  or  bullock  they  are 
large  enough  to  admit  a  small  probe. 
The  secretion  of  the  gland  keeps  the 
surface  of  the  cornea  constantly 
moist  and  polished ;  but  if  dust,  or 

any  foreign  substance,  irritate  the  eye,  the  tears  flow  in  abundance, 
and  wash  it  off. 

All  the  muscles  of  the  orbit,  with  the  exception  of  the  inferior 
oblique,  arise  from  the  margin  of  the  foramen  opticum,  and  pass 
forwards,  like  ribands,  to  their  insertions. 

LEVATOB  This  muscle  arises  from  the  roof  of  the  orbit, 

PALPEBK^:.  above    and   in   front    of  the    optic   foramen.     It 

gradually  increases  in  breadth,  and  terminates  in  a  broad,  thin 
aponeurosis,  which  is  inserted  into  the  upper  surface  of  the  tarsal 
cartilage  beneath  the  palpebral  ligament.  It  is  constantly  in 
action  when  the  eyes  are  open,  in  order  to  counteract  the  ten- 
dency of  the  lids  to  fall.  As  sleep  approaches,  the  muscle  relaxes, 
the  eyes  feel  heavy,  and  the  lids  close.  Its  nerve  comes  from  the 
superior  division  of  the  third  nerve,  and  enters  it  on  its  under  or 
ocular  aspect. 

1  This  capsule,  being  a  little  stronger  on  the  under  surface  of  the  gland,  is 
described  and  figured  by  Sommerring  as  a  distinct  ligament,  Icones  Oculi 
Humani,  tab.  vii. 


MUSCLES    OF   THE    ORBIT.  55 

OBLIQUUS  This  muscle  arises  from  the  inner  side  of  the 

SUPERIOR.  optic  foramen.  It  runs  forwards  along  the  inner 

and  upper  side  of  the  orbit,  and  terminates  in  a  round  tendon, 
which  passes  through  a  fibro-cartilaginous  pulley — trochlea — 
attached  to  the  trochlear  fossa  in  the  frontal  bone.  From  the  pulley 
the  tendon  is  reflected  outwards  and  backwards,  beneath  the  supe- 
rior rectus,  and  is  inserted  by  an  expanded  tendon  into  the  outer  part 
of  the  sclerotic  coat,  midway  between  the  cornea  and  the  entrance 
of  the  optic  nerve.  The  pulley  is  lined  by  a  synovial  membrane, 
which  is  continued  over  the  tendon.  The  action  of  this  muscle 
will  be  considered  with  that  of  the  inferior  oblique.  It  is  supplied 
by  the  fourth  nerve,  which  enters  the  back  part  of  its  upper 
surface. 

The  frontal  nerve  and  levator  palpebrse  are  now  to  be  cut 
through  the  middle  and  reflected,  the  front  part  forwards  and  the 
hind  part  backwards.  On  its  under  aspect  is  seen  the  twig  from 
the  upper  division  of  the  third  nerve  entering  it.  On  reflecting 
this  muscle  the  superior  rectus  is  exposed. 

The  superior  rectus  arises  by  a  tendinous  origin  from  the  upper 
margin  of  the  optic  foramen  and  from  the  sheath  of  the  optic 
nerve,  and  is  inserted  by  a  broad  thin  tendon  into  the  sclerotic  coat, 
about  a  quarter  of  an  inch  from  the  margin  of  the  cornea  (p.  61). 

Reflect   this   muscle    by   cutting   through   the 
DISSECTION.  . 

middle,  and,  in  doing  so,  observe  a  filament  from 

the  third  nerve  entering  its  under  aspect.  After  the  removal  of  a 
quantity  of  granular  fat,  the  following  objects  are  exposed  :  beneath 
the  muscle  are  the  optic  nerve,  the  ophthalmic  artery  and  vein, 
the  nasal  nerve  and  its  ciliary  branches  crossing  over  the  optic 
nerve,  and  further  forwards  is  the  reflected  tendon  of  the  superior 
oblique ;  on  the  outer  side  of  the  optic  nerve,  and  close  to  the 
ophthalmic  artery,  is  the  lenticular  ganglion,  with  numerous  ciliary 
filaments  passing  forwards  from  it  to  enter  the  sclerotic.  The 
student  should  now  trace  backwards  the  two  roots  which  enter  the 
upper  and  lower  angle  respectively  of  the  ganglion,  the  upper 
being  its  sensory  branch  from  the  nasal,  the  lower  its  motor  root 
from  the  lower  division  of  the  third  nerve.  Further  back  should 
be  traced  the  third,  the  nasal  branch  of  the  ophthalmic,  and  the 


56  NASAL   NERVE   IN   THE   ORBIT. 

sixth  nerves  passing  between  the  two  heads  of  the  external  rectus 
to  their  respective  destinations.  The  ophthalmic  artery  and  its 
branches  may  also  at  this  stage  be  exposed  and  cleaned. 

This  is  one  of  the  three  divisions  of  the  oph- 
thalmic branch  of  the  fifth,  and  is  usually  the 
first  branch  given  off  (fig.  19,  p.  50).  It  enters  the  orbit  through 
the  sphenoidal  fissure  between  the  two  origins  of  the  external 
rectus,  and  between  the  two  divisions  of  the  third  n.  It  then 
crosses  obliquely  over  the  optic  nerve,  beneath  the  levator  palpebrse 
and  the  superior  rectus,  towards  the  inner  wall  of  the  orbit.  After 
giving  off  the  infra-trochlear  branch,  the  nerve  passes  out  of  the 
orbit  between  the  superior  oblique  and  internal  rectus,  through  the 
anterior  ethmoidal  foramen,  into  the  cranium,  where  it  lies  beneath 
the  dura  mater,  upon  the  cribriform  plate  of  the  ethmoid  bone.  It 
soon  leaves  the  cranium  through  the  nasal  slit  near  the  crista  galli, 
and  enters  the  nose.  Here  it  divides  into  two  branches — an  inner 
or  septal,  which  supplies  the  mucous  membrane  of  the  front  of  the 
septum  ;  and  an  outer,  the  main  continuation  of  the  nerve — which 
runs  in  a  groove  on  the  under  surface  of  the  nasal  bone,  and 
distributes  branches  to  the  pituitary  membrane  of  the  outer  part 
of  the  nose  and  the  two  lower  turbinated  bones  ;  it  also  gives  off  a 
superficial  branch,  which  emerges  between  the  nasal  bone  and  the 
cartilage,  under  the  name  of  the  naso-lobular,  and  is  distributed  to 
the  skin  of  the  tip  and  ala  of  the  nose  (p.  49). 

The  nasal  nerve  gives  off  the  following  branches  in  the  orbit : — 

a.  One  slender  filament  to  the  lenticular  yanylion  (forming  its  upper 
or  long  root)  is  given  off  from  the  nasal  nerve  as  it  passes  between  the 
heads  of  the  external  rectus  close  to  the  optic  nerve.     It  is  about  half 
an  inch  long,  and  enters  the  posterior- superior  angle  of  the  ganglion. 

b.  Two  or  three  long  ciliary  nerves.     They  run  along  the  inner  side 
of  the  optic  nerve  to  the  back  of  the  globe  of  the  eye.     They  are  joined 
by  filaments  from  the  lenticular  ganglion,  and  pass  through  the  sclerotic 
coat  to  supply  the  iris  (fig.  22). 

c.  Infra-trochlear  nerve. — This  runs  forwards  along  the  inner  side  of 
the  orbit,  below  the  pulley  of  the  superior  oblique,  where  it  communi- 
cates with  the  supra-trochlear  branch  of  the  frontal  nerve.     It  passes  to 
the  inner  angle  of  the  orbit,  and  divides  into  filaments,  Avhich  supply  the 


OPHTHALMIC    ARTERY. 


57 


skin  of  the  eyelids,  the  caruncle,  the  lachrymal  sac,  and  the  side  of  the 

nose. 

FIG.  22. 


CILIARr  GANGLION 


OPTIC  NERVE. 


VIEW    OF    OPTIC    AND    LOWER    NERVES    OF    ORBIT. 

This  nerve,  having  passed  through  the  optic 
foramen,  proceeds  forwards  and  a  little  outwards 
for  about  an  inch  to  the  globe  of  the  eye,  which  it  enters  on  the 
nasal  side  of  its  axis.  It  pierces  the  sclerotic  and  choroid  coats, 
and  then  expands  to  form  the  retina.  The  nerve  is  invested  by  a 
dense  fibrous  coat  derived  from  the  dura  mater,  and  by  a  thin  one 
from  the  arachnoid,  both  of  which  pass  forwards  as  far  as  the 
sclerotic.  At  the  optic  foramen  it  is  surrounded  by  the  tendinous 
origins  of  the  recti ;  in  the  rest  of  its  course,  by  loose  fat  and  by 
the  ciliary  nerves  and  arteries.  It  is  pierced  in  its  course  through 
the  orbit  by  the  arteria  centralis  retinae  which  runs  along  with  its 
vein  in  the  middle  of  the  nerve  to  the  eyeball.1 

OPHTHALMIC  This  artery  arises  from  the  internal  carotid,  close 

ARTERY.  by  the  anterior  clinoid  process.    It  enters  the  orbit 

through  the  optic  foramen,  outside  and  below  the  optic  nerve ; 
occasionally  through  the  sphenoidal  fissure.  Its  course  in  the 
orbit  is  remarkably  tortuous.  Situated  at  first  on  the  outer  side 
of  the  optic  nerve,  it  soon  crosses  over  it,  and  runs  along  the  inner 

1  A  small  branch  from  Meckel's  ganglion,  ascending  through  the  spheno-maxil- 
lary  fissure,  is  described  by  Arnold  as  joining  the  optic  nerve. 


58  LACHRYMAL    ARTERY. 

side  of  the  orbit  between  the  superior  and  internal  recti,  to  inoscu- 
late with  the  internal  angular  artery  (the  terminal  branch  of  the 
facial).  Its  branches  arise  in  the  following  order  : — 

a.  Lachrymal  artery. — This  branch  proceeds  along  the  outer  wall  of 
the  orbit  above  the  external  rectus,  in  company  with  the  nerve  of  the 
same  name  to  the  lachrymal  gland.     After  supplying  the  gland,  it  ter- 
minates in  the  conjunctiva  and  eyelids.     In  the  orbit  it  gives  off  some 
malar  branches  which  pierce  the  malar  bone  to  get  to  the  temporal 
fossa,  and  anastomose  with  the  deep  temporal  arteries.     It  also  sends  a 
branch  backwards  through  the  sphenoidal  fissure  to  anastomose  with 
the  arteria  meiihigea  media. 

b.  Supra-orbital  artery. — This  branch  runs  forwards  with  the  frontal 
nerve  under  the  roof  of  the  orbit  and  upon  the  levator  palpebrae.     It 
emerges  on  the  forehead  through  the  supra-orbital  foramen,  where  it 
communicates  with  the  superficial  temporal,  frontal  and  angular  arteries. 

c.  Arteria  centralis  retina;. — This   small   branch    enters   the   optic 
nerve  obliquely  on  the  outer  aspect  close  to  the  optic  foramen.     It  runs 
in  the  centre  of  this  nerve  to  the  interior  of  the  eye. 

d.  Ciliary   arteries. — These   branches   may   be    arranged   in   three 
groups.     The  short  ciliary,  twelve  to  fifteen  in  number,  proceed  tor- 
tuously forwards  with  the  optic  nerve,  and  pierce  the  sclerotic  coat  at 
the  back  of  the  eye  to  supply  the  choroid  coat  and  the  iris.     The  long 
ciliary,  two  in  number,  run  on  each  side  of  the  optic  nerve,  enter  the 
sclerotic,    and   pass   horizontally   forwards,   one   on   each  side  of   the 
globe,  between  the  sclerotic  and  the  choroid,  nearly  as  far  as  the  iris 
where  each  divides  into  an  upper  and  a  lower  branch.     These  branches 
of  the  two  long  ciliary  arteries  anastomose  with  the  anterior  ciliary  and 
form  two  vascular  circles,  an  outer  at  the  circumference  of  the  iris,  the 
circuit  is  major  and  an  inner  at  the  free  margin  of  the  iris,  the  circulus 
minor.     The  anterior  ciliary  are  branches  of  the  muscular  and  lachry- 
mal arteries  and  proceed  with  the  tendons  of  the  recti,  and  enter  the 
front  part  of  the  sclerotic  coat.    In  inflammation  of  the  iris  the  vascular 
zone  round  the  cornea  arises  from  enlargement  and  congestion  of  the 
anterior  ciliary  arteries. 

e.  JSthmoidal  arteries. — Of  these  arteries,  two  in  number,  the 
anterior  and  larger  passes  through  the  anterior  ethmoidal  foramen  with 
the  nasal  nerve  ;  the  posterior  enters  the  posterior  ethmoidal  foramen 
with  the  spheno-ethmoiclal  nerve.  The  anterior  gives  off  brandies  to 
the  frontal  and  anterior  ethmoidal  cells,  and  a  nasal  branch  to  the 
nose  ;  it  likewise  gives  off  an  anterior  meningeal  branch  to  the  dura 


LENTICULAR   GANGLION.  59 

mater  in  the  anterior  fossa.  The  posterior  is  distributed  to  the  pos- 
terior ethmoidal  cells  and  upper  part  of  the  nose. 

f.  Muscular  branches. — There  is   an  upper  and  a  lower  branch  sup- 
plying respectively  the  upper  and  lower  muscles  :  besides  these,  there 
are  irregular  branches  from  the  lachrymal  and  supra-orbital  arteries. 

g.  Palpebral  arteries.— These  branches,  a  superior  and  an  inferior, 
proceed  from  the  ophthalmic  artery  near  the  front  of  the  orbit.     They 
are  distributed  to  their  respective   eyelids,   forming   arches  near  the 
margins  of  the  lids  between  the  tarsal  cartilages  and  the  orbicularis 
palpebrarum  with  branches  from  the  lachrymal  and  the  infra-orbital 
arteries. 

h.  Nasal  artery. — This  branch  may  be  considered  one  of  the  ter- 
minal divisions  of  the  ophthalmic.  It  leaves  the  orbit  on  the  nasal  side 
of  the  eye  above  the  tendon  of  the  orbicularis,  and  inosculates  with  the 
angular  and  nasal  arteries  of  the  facial.  It  supplies  the  side  of  the 
nose  and  the  lachrymal  sac. 

i.  Frontal  artery. — This  is  the  other  terminal  branch  of  the  oph- 
thalmic. It  emerges  at  the  inner  angle  of  the  eye,  ascends,  and  inoscu- 
lates with  the  supra-orbital  artery. 

OPHTHALMIC  There  are  two  ophthalmic  veins.  The  superior 

VEINS.  commences  at  the  inner  angle  of. the  eye  by  a 

communication  with  the  frontal  and  angular  veins.  It  runs  back- 
wards above  the  optic  nerve  in  a  straighter  course  than  the  artery, 
receives  the  veins  corresponding  to  the  arteries  of  the  upper  and 
inner  part  of  the  orbit,  and  finally  passes  between  the  two  heads  of 
the  external  rectus,  through  the  inner  part  of  the  spkenoidal  fissure, 
to  terminate  in  the  cavernous  sinus.  The  inferior  ophthalmic  vein 
is  formed  by  the  union  of  branches  from  the  lower  and  outer  part 
of  the  orbit,  and  proceeding  backwards  along  the  floor  of  the  orbit, 
opens  into  the  superior  vein,  or  directly  into  the  cavernous  sinus. 
In  front  it  sends  a  communicating  vein  through  the  spheno- 
maxillary  fissure  to  join  the  pterygoid  plexus. 

OPHTHALMIC  OB  Tnis  sma11  ganglion  '  (fig.  19,  p.  50),  of  reddish 
LENTICDLAB  colour  and  about  the  size  of  a  pin's  head,  is  situ- 

GANGLION.  ated  at  tlie  back  of  the  orbit,  between  the  optic 

nerve  and  the  external  rectus,  on  the  outer  side  of,  and  usually 

1  W.  Marshall  regards  this  ganglion,  from  its  mode  of  development  and  from 
its  relations  in  some  of  the  lower  vertebrates,  to  be  connected  more  with  the  third 
nerve  than  the  ophthalmic. 


60  THIRD    NERVE. 

closely  adherent  to,  the  ophthalmic  artery.  It  is  somewhat  quadri- 
lateral in  shape,  and  receives  its  sensory  or  long  root  from  the  nasal 
nerve,  which  joins  its  posterior  superior  angle ;  its  motor  or  short 
root,  from  the  branch  of  the  third  nerve,  going  to  the  inferior 
oblique,  which  enters  its  posterior  inferior  angle  ;  and  its  sympa- 
thetic root  from  the  cavernous  plexus  which  joins  it  at  its  posterior 
border,  or  in  conjunction  with  its  sensory  root.  The  ganglion, 
thus  furnished  with  motor,  sensory  and  sympathetic  roots,  gives  off 
the  short  ciliary  nerves.  These,  from  eight  to  twelve  in  number, 
issue  from  the  anterior  upper  and  lower  angles  of  the  ganglion, 
usually  four  or  five  from  the  upper,  the  remainder  from  the  lower. 
They  run  very  tortuously  with  the  optic  nerve,  pass  through  the 
back  of  the  sclerotic  coat,  where  they  are  joined  by  the  long  ciliary 
(from  the  nasal),  and  are  distributed  to  the  iris  and  the  ciliary 
muscle.  Since  the  ciliary  nerves  derive  their  motor  influence  from 
the  third  nerve,  the  iris  must  lose  its  power  of  contraction  when 
this  nerve  is  paralysed. 

THIRD  NEBVE,  The  third  nerve  passes  forwards  in  the  outer 

MOTOR  OCULI.  wall  of  the  cavernous  sinus,  and  here  receives  one 

or  two  filaments  from  the  cavernous  plexus  of  the  sympathetic. 
Just  before  it  enters  the  inner  end  of  the  sphenoidal  fissure  it 
divides  into  two  branches,  both  of  which  pass  between  the  two 
heads  of  origin  of  .the  external  rectus,  separated  from  each  other 
by  the  nasal  nerve.  The  upper  and  smaller  division  has  been 
already  traced  into  the  superior  rectus  and  levator  palpebrae.  The 
lower  division  after  a  short  course  divides  into  three  branches,  one 
passing  inwards  under  the  optic  nerve  to  supply  the  internal  rectus, 
another  passes  to  the  inferior  rectus,  and  a  third  runs  along  the 
floor  of  the  orbit  to  the  inferior  oblique  (fig.  19).  This  last-named 
branch  sends  a  small  twig  upwards  to  the  lenticular  ganglion, 
mentioned  in  the  description  of  this  ganglion,  and  another  to  the 
inferior  rectus. 

What  is  the  result  of  paralysis  of  the  third  nerve  ?  Falling  of 
the  upper  eyelid  (ptosis),  external  squint,  dilatation  and  immobility 
of  the  pupil. 

SIXTH  NERVE,  This  nerve  lies  in  the  inner  wall  of  the  cavernous 

ABDUCENS.  sinus  external  to  the  internal  carotid  artery,  passes 


RECTI   MUSCLES.  61 

through  the  sphenoidal  fissure,  and  enters  the  orbit  between  the 
two  heads  of  the  external  rectus.  Here  it  lies  below  the  lower 
division  of  the  third  and  above  the  ophthalmic  vein.  The  nerve 
terminates  in  fine  filaments,  which  are  distributed  to  the  ocular 
surface  of  the  external  rectus.  In  the  cavernous  sinus  it  is  joined 
by  filaments  from  the  carotid  plexus,  and  in  the  orbit  by  a  branch 
from  Meckel's  ganglion  and  from  the  ophthalmic  nerve. 

Respecting  the  motor  nerves  in  the  orbit,  observe  that  they 
all  enter  the  ocular  surface  of  the  muscles,  with  the  exception 
of  the  fourth,  which  enters  the  orbital  surface  of  the  superior 
oblique. 

The  internal  and  inferior  recti  arise  from  a  fibrous 
BECTI  MUSCLES.      ,        -,      ,,      7.  ,,„.  ,     ,          , 

band — the  ligament  oj  Z/inn — attached  to  the  inner 

and  lower  borders  of  the  optic  foramen.  The  external  rectus  arises 
by  two  heads,  the  lower  from  the  ligament  of  Zinn  and  the  lower 
border  of  the  sphenoidal  fissure,  the  upper  from  the  margin  of  the 
foramen  opticum ;  between  these  heads  pass  in  the  following  order, 
from  above  downwards — the  upper  division  of  the  third,  the  nasal , 
the  lower  division  of  the  third,  the  sixth  nerves,  and  the  ophthalmic 
vein. 

The  four  recti  diverge  from  each  other,  one  above,  one  below, 
and  one  on  each  side  of  the  optic  nerve.  Their  broad  thin  tendons 
are  inserted  into  the  sclerotic  coat  of  the  eye,  about  a  quarter  of 
an  inch  from  the  margin  of  the  cornea  (fig.  23). 

The  recti  muscles  enable  us  to  direct  the  eye  towards  different 
points ;  hence  the  names  given  to  them  by  Albinus — attollens, 
depressor,  adductor,  and  abductor  oculi.  It  is  obvious  that  by  the 
single  action  of  one,  or  the  combined  action  of  two,  the  eye  can  be 
turned  towards  any  direction. 

The  rectus  superior  as  supplied  by  the  upper  division  of  the 
third  nerve ;  the  rectus  internus,  the  rectus  inferior  and  obliquus 
inferior,  by  the  lower  division.  The  rectus  externus  is  supplied  by 
the  sixth. 

Follow  the  recti  to  the  eye,  in  order  to  see  the  tendons  by  which 
they  are  inserted.  Notice  also  the  anterior  ciliary  arteries,  which 
run  to  the  eye  along  the  tendons.  The  congestion  of  these  little 
vessels  occasions  the  red  zone  round  the  cornea  in  iritis.  It  has 


G2 


INSERTION    OF   THE    RECTI    MUSCLES. 


INSERTION    OF    THE  EECTI  MUSCLES  WITH 
THE    ANTERIOR    CILIARY    ARTERIES. 


been  already  mentioned  that  the  tendons  are  invested  by  a  fascia, 
which  passes  from  one  to  the  other,  forming  a  loose  tunic — capsule 
FlG  23.  °f  Tenon — over   the   back  of  the 

eye.  This  tunic  consists  of  two 
layers  with  an  intermediate  space, 
lined  with  flat  cells,  thus  allow- 
ing free  mobility  of  the  globe. 
It  is  this  fascia  which  resists  the 
passage  of  the  hook  in  the  ope- 
ration for  the  cure  of  squinting. 
Even  after  the  complete  division 
of  the  tendon,  the  eye  may  still 
be  held  in  its  faulty  position,  if 
this  tissue,  instead  of  possessing  its 
proper  softness  and  pliancy,  happen 
to  have  become  contracted  and  un- 
yielding. Under  such  circumstances  it  is  necessary  to  divide  it 
freely  with  the  scissors. 

By  removing  the  conjunctival  coat  of  the  eye,  the  tendons  of 
the  recti  are  soon  exposed.  The  breadth  and  the  precise  situation 
of  their  insertion  deserve  attention  in  reference  to  the  operation 
for  strabismus.  The  breadth  of  their  insertion  is  about  three- 
eighths  of  an  inch,  but  the  line  of  this  insertion  is  not,  at  all  points, 
equidistant  from  the  cornea.  The  centre  of  the  insertion  is  nearer 
to  the  cornea  by  about  one  line  than  either  end.  Taking  the 
internal  rectus,  which  has  most  frequently  to  be  divided  in  strabis- 
mus, we  find  that  the  centre  of  its  tendon  is,  upon  an  average, 
three  lines  only  from  the  cornea,  the  lower  part  nearly  five  lines, 
and  the  upper  four.  It  is,  therefore,  very  possible  that  the  lower 
part  may  be  left  undivided  in  the  operation,  being  more  in  the 
background  than  the  rest.  The  tendon  of  the  internal  rectus  is 
nearer  to  the  cornea  than  either  of  the  others. 

INFERIOR  This  muscle  arises  by  a  flat  tendon  from  the 

OBLIQUE.  orbital  plate  of  the  superior  maxilla  on  the  outer 

side  of  the  lachrymal  groove.  It  runs  outwards  and  backwards 
between  the  orbit  and  the  inferior  rectus,  then  curves  upwards  be- 
tween the  globe  and  the  external  rectus,  and  is  inserted  by  a  broad 


DISSECTION    OF    THE    NECK.  63 

thin  tendon  into  the  outer  and  back  part  of  the  sclerotic,  close  to 
the  tendon  of  the  superior  oblique.1  It  is  supplied  by  the  lower 
division  of  the  third  nerve. 

The  tensor  tarsi  muscle  has  been  described  in  the  dissection  of 
the  face  (p.  34). 

ORBITAL  This  is    always  very  small,   and  is  sometimes 

BRANCH  OF  THE  absent.  It  comes  from  the  trunk  of  the  superior 
SUPERIOR  MAXIL-  maxillary  in  the  spheno-maxillary  fossa,  enters 
the  orbit  through  the  spheno-maxillary  fissure, 
and  divides  into  two  branches.  Of  these,  one,  the  temporal,  lies 
in  a  groove  in  the  outer  wall  of  the  orbit,  and  after  sending  a 
small  branch  to  the  lachrymal  nerve  in  the  orbit,  passes  through  a 
foramen  in  the  malar  bone  to  the  temporal  fossa.  It  then  pierces 
the  temporal  aponeurosis  an  inch  above  the  zygoma,  and  supplies 
the  skin  of  the  temple  communicating  with  the  facial,  and  join- 
ing frequently  with  the  auriculo-temporal  branch  of  the  inferior 
maxillary.  The  other  branch,  the  malar,  passes  along  the  outer 
part  of  the  floor  of  the  orbit,  imbedded  in  fat,  and  makes  its  exit 
through  a  foramen  in  the  malar  tone,  to  supply  the  skin  of  the 
cheek  over  the  malar  bone  (p.  49). 

DISSECTION   OF   THE   NECK. 

SURFACE  Before  the  student  reflects  the  skin  of  the  neck 

MARKING.  he  should  examine  the  skin  surface,  which  in  some 

places  is  raised,  in  others  depressed,  indicating  thereby  unevenness 
of  the  subjacent  structures.  The  neck  is  bounded  above  by  a  well- 
marked  transverse  ridge,  indicating  the  lower  border  of  the  inferior 
maxilla,  and  at  its  lower  part  the  neck  is  bounded  by  another  ridge 
which  corresponds  with  the  clavicle.  Crossing  obliquely  from  the 
centre  of  the  neck  below  to  the  mastoid  process  above,  is  the 
rounded  prominence  caused  by  the  sterno-mastoid,  and  crossing 
this  muscle  diagonally  from  its  anterior  to  its  posterior  border  is 
the  external  jugular  vein,  which  varies  in  size  in  different  subjects. 
In  front  and  behind  the  sterno-mastoid  are  two  triangular  depres- 

1  On  the  action  of  the  recti  and  oblique  muscles,  consult  M.  Foster,  Text-Book 
of  Physiology . 


64  PLATYSMA   MYOIDES. 

sions  ;  the  posterior  one,  it  will  be  seen,  has  its  base  at  the  clavicle, 
the  anterior  one  at  the  lower  jaw.  The  posterior  triangle  has  the 
trapezius  as  its  outer  boundary,  but  this  border  is  only  well  defined 
iiiferiorly,  where  the  hollow  becomes  most  marked,  and  takes  the 
name  of  the  supra-clavicular  or  Mohrenheiin's  fossa.  In  this  is 
placed  deeply  the  subclavian  artery,  the  posterior  belly  of  the 
omo-hyoid,  and  the  brachial  plexus.  In  front  of  the  sterno- 
mastoid  is  another  triangular  hollow  space  with  its  base  upwards ; 
this  is  called  the  carotid  triangle,  for  in  it  lies  the  carotid  artery 
immediately  beneath  the  anterior  border  of  the  sterno-mastoid. 
The  body  of  the  hyoid  bone  can  always  be  felt  in  the  middle  line 
below  the  symphysis  of  the  lower  jaw.  About  a  finger's  breadth 
below  the  hyoid  is  the  prominent  pomum  Adami  of  the  thyroid 
cartilage,  and  a  short  distance  below  this  cartilage  is  the  cricoid, 
separated  from  the  cartilage  above  by  the  crico-thyroid  membrane. 
The  cricoid  cartilage  corresponds  with  the  fifth  cervical  vertebra, 
and  from  it  the  trachea  passes  down,  gradually  receding  from  the 
surface,  so  that  there  is,  especially  in  emaciated  subjects,  a  deep 
hollow — fonticulus  gutturis — immediately  above  the  sternum.  In 
front  of  the  second,  third,  and  fourth  rings  of  the  trachea  is  the 
isthmus  of  the  thyroid  gland,  and  there  are  usually  another  four 
rings  below  these  above  the  sternum,  covered  more  or  less  by  the 
depressor  muscles  of  the  os  hyoides. 

The  head  must  be  slightly  raised,  and  the  face 
turned  from  the  side  on  which  the  dissection  is  to 
be  made.  Then  make  a  vertical  incision  through  the  skin,  down 
the  middle  of  the  neck  from  the  symphysis  of  the  lower  jaw  to  the 
sternum ;  a  second  along  the  clavicle  to  the  acromion ;  a  third 
along  the  base  of  the  jaw  as  far  as  the  mastoid  process.  Reflect 
the  skin  and  subcutaneous  fat,  and  expose  the  cutaneous  muscle, 
called  the  platysma  myoides.  Between  the  platysma  and  the  skin 
is  a  layer  of  adipose  tissue,  called  the  superficial  fascia.  It  varies 
in  thickness  in  different  subjects,  but  is  generally  more  abundant  at 
the  upper  part  of  the  neck,  especially  in  corpulent  individuals,  in 
whom  it  occasions  a  double  chin. 

PLATYSMA  '^e  l^citysma   myoides  is  the   thin    cutaneous 

MYOIDES.  muscle  covering  the  front  and  side  of  the  neck. 


DISSECTION   OF   THE   NECK.  65 

It  arises  from  the  subcutaneous  tissue  over  the  pectoralis  major, 
trapezius  and  deltoid  muscles  ; l  thence  proceeding  obliquely  over 
the  clavicle  and  the  side  of  the  neck,  its  fibres  become  more  closely 
aggregated,  and  terminate  thus  : — The  anterior  cross  those  of  the 
opposite  platysma,  immediately  below  the  symphysis  of  the  jaw, 
and  are  lost  in  the  skin  of  the  chin ;  the  middle  are  attached  along 
the  base  of  the  jaw ;  the  posterior  cross  the  masseter  muscle,  and 
terminate,  partly  in  the  subcutaneous  tissue  of  the  cheek,  partly  in 
the  muscles  at  the  corner  of  the  mouth  blending  with  the  depressor 
anguli  oris  and  orbicularis.2 

The  platysma  forms  a  strong  muscular  defence  for  the  neck. 
It  is  also  a  muscle  of  expression.3  It  is  supplied  with  nerves 
by  the  cervical  plexus,  and  by  the  cervical  branch  of  the  facial 
nerve. 

Cut  through  the  platysma  near  the  clavicle  and 
turn  it  upwards.  Beneath  it  lies  the  general  in- 
vestment of  the  neck,  called  the  deep  cervical  fascia.  Upon  this 
fascia  we  trace  the  superficial  branches  of  the  cervical  plexus  of 
nerves,  the  external  jugular  vein,  and  a  smaller  vein  in  front, 
called  the  anterior  jugular.  These  superficial  veins  are  so  variable 
in  size  and  course,  that  a  general  description  only  is  applicable. 

1  Some  anatomists  describe  it  as  having  a  slender  origin  from  the  clavicle  and 
the  acromion. 

2  Some  of  the  uppermost  fibres  of  this  part  of  the  platysma  take  the  name  of 
musculus  risorius  :  this  has  been  described  among  the  muscles  of  the  face. 

3  If  the  entire  muscle  be  permanently  contracted  it  may  occasion  wry-neck, 
though  distortion  from  such  a  cause  is  an  exceedingly  rare  occurrence.     A  case  in 
point  is  related  by  Mr.  Gooch  (Chirurg.  Works),  in  which  a  complete  cure  was 
effected,  after  the  failure  of  all  ordinary  means  of  relief,  by  the  division  of  the 
platysma  a  little  below  the  jaw. 

The  platysma  myoides  belongs  to  a  class  of  muscles  called  cutaneous,  from 
their  office  of  moving  the  skin.  There  are  not  many  in  man,  except  upon  the 
neck  and  face,  and  there  is  a  little  one  (palmaris  brevis)  in  the  palm  of  the  hand. 
To  understand  their  use  thoroughly  we  must  refer  to  the  lower  orders  of  animals, 
in  whom  they  fulfil  very  important  functions,  by  moving  not  only  the  skin,  but 
also  its  appendages.  For  instance,  by  muscles  of  this  kind  the  hedgehog,  porcu- 
pine, and  animals  of  that  family  can  roll  themselves  up  and  erect  their  quills  :  we 
are  all  familiar  with  the  broad  '  panniculus  carnosus  '  on  the  sides  of  herbivorous 
quadrupeds,  which  enables  them  to  twitch  their  skins,  and  thus  rid  themselves  of 
insects.  In  birds,  too,  these  cutaneous  muscles  are  extremely  numerous,  each 
feather  having  appropriate  muscles  to  move  it. 

F 


66 


EXTERNAL  JUGULAR  VEIN. 


EXTERNAL  The  external  jugular  vein  is  formed  within  the 

JUGULAR  VEIN.  substance  of  the  parotid  gland  by  the  junction  of 
the  temporal  and  internal  maxillary  veins.  After  receiving  the 
transverse  facial  and  posterior  auricular  veins,  it  appears  at  the 
lower  border  of  the  gland,  crosses  obliquely  over  the  sterno-mastoid 
muscle  (fig.  24),  running  along  its  posterior  border,  nearly  as  low 
down  as  the  clavicle,  where  it  pierces  the  deep  cervical  fascia  and 
terminates  in  the  subclavian  vein.  Accompanying  the  vein  in  its 

FIG.  24. 


Cervical  branch  of 
facial  n.     .     .     . 


Superficial  cervical 
nerve     .... 

External  jugu- 
lar v 

Anterior  jugu- 
lar v. 


Small  occipital  n. 


Auricularis 
magnus  n. 

Nervus  acces- 
sorius. 

Descending 
branch  of  cer- 
vical plexus. 


UIAGKAM   OF   THE    SUPERFICIAL    NERVES   AND    VEINS   OF   THE   NECK. 

upper  part  is  the  auricularis  magnus  nerve,  and  crossing  it,  about 
the  middle,  is  the  superficial  cervical  nerve,  both  being  branches  of 
the  superficial  cervical  plexus.  It  is  usually  provided  with  two 
pairs  of  valves — the  lower,  imperfect,  close  to  its  termination  in 
the  subclavian  vein ;  the  upper,  placed  about  an  inch  and  a  half 
above  the  clavicle'.  A  line  drawn  from  the  angle  of  the  jaw  to  the 
middle  of  the  clavicle  would  indicate  its  course.  To  trace  the  vein, 
during  life,  press  upon  it  just  above  the  clavicle ;  but  do  not 
be  surprised  if  you  fail  to  find  it :  it  is  sometimes  wanting,  and 
frequently  very  small. 


CUTANEOUS  NERVES  OF  THE  NECK.  67 

Near  the  angle  of  the  jaw  the  external  jugular  vein  communi- 
cates by  a  large  branch  with  the  internal  jugular,  and  about  its 
middle  it  is  joined  by  a  large  vein — posterior  external  jugular — 
from  the  occipital  region. 

Before  its  termination  the  external  jugular  vein  generally 
receives  the  supra-scapular,  posterior  scapular,  and  other  unnamed 
veins  :  a  disposition  very  embarrassing  to  the  surgeon,  because  there 
is  a  confluence  of  veins  immediately  over  the  subclavian  artery  in  the 
place  where  it  is  usually  tied. 

ANTERIOR  The  anterior  jugular  vein  is  situated  more  in 

JUGULAR  VEIN.  the  middle  of  the  neck,  and  is  much  smaller  than 
the  external  jugular.  It  commences  by  small  branches  below  the 
chin,  and  runs  down  the  front  of  the  neck,  nearly  to  the  sternum  ; 
it  then  curves  outwards,  beneath  the  sterno-mastoid  muscle,  and 
opens  either  into  the  external  jugular  or  the  subclavian  vein.  We 
commonly  meet  with  two  anterior  jugular  veins,  one  on  either  side ; 
immediately  above  the  sternum  they  communicate  by  a  transverse 
branch. 

The  size  of  the  anterior  jugular  vein  is  inversely  proportionate 
to  that  of  the  external  jugular.  When  the  external  jugular  is 
small,  or  terminates  in  the  internal  jugular,  then  the  anterior 
jugular  becomes  an  important  supplemental  vein,  and  attains  con- 
siderable size.  It  is  not  uncommon  to  find  it  a  quarter  of  an  inch 
in  diameier,  and  we  have  seen  it  nearly  half  an  inch.  These 
varieties  should  be  remembered  in  tracheotomy. 

Superficial  lymphatic  glands  are  sometimes  found  near  the 
cutaneous  veins  of  the  neck.  From  four  to  six  in  number,  they 
are  small  and  escape  observation  unless  enlarged  by  disease.  One 
or  two  are  situated  over  the  sterno-mastoid  muscle ;  others,  near 
the  mesial  line. 

CUTANEOUS  The  cutaneous  nerves  of  the  neck  are  the  super- 

NERVES  OF  THE  ficial  branches  of  the  cervical  plexus  :  the  plexus 
NECK-  itself  cannot  at  present  be  seen.  It  is  formed  by 

the  communications  of  the  anterior  divisions  of  the  four  upper  cer- 
vical nerves,  and  lies  under  the  sterno-mastoid  muscle,  close  to 
the  transverse  processes  of  the  four  upper  cervical  vertebrae,  resting 
on  the  levator  anguli  scapulas  and  the  scalenus  medius.  The  super- 

F   2 


C8  CUTANEOUS  NERVES  OF  THE  NECK. 

ficial  branches  of  the  plexus  emerge  from  beneath  the  posterior 
border  of  the  sterno-mastoid,  and  take  different  directions.  They 
are  named  thus  (fig.  24)  : — 

/ .  f  Great  auricular. 

Ascending  branches  .        .        .  j  gmall  occipital> 

Superficial  branches  of  J  Transverse  branch     .  .        .     Superficial  cervical, 
the  cervical  plexus.        I  ( Sternal. 

Descending  branches  .        .  j  Clavicular. 
V  I  Acromial. 

The  great  auricular  n.  comes  from  the  second  and  third  cervical 
nerves,  winds  round  the  posterior  border  of  the  sterno-mastoid,  and 
ascends  obliquely  over  that  muscle,  near  the  external  jugular  vein, 
towards  the  parotid  gland.  Near  the  gland  it  divides  into  two  prin- 
cipal branches,  of  which  the  anterior  or  facial  branches  are  distributed 
to  the  skin  over  the  parotid  gland,  where  they  join  branches  from  the 
facial  nerve,  and  to  the  side  of  the  cheek  ;  the  posterior  or  auricular, 
after  ascending  a  short  distance,  give  off  a  branch,  which  ramifies 
mainly  upon  the  cranial  aspect  of  the  cartilage  of  the  ear  ;  and  a 
smaller  branch,  the  mastoid,  which  supplies  the  skin  over  the  mastoid 
process.  Other  filaments  of  this  nerve  communicate  in  the  substance 
of  the  parotid  gland  with  branches  of  the  facial  nerve. 

The  small  occipital  n.  comes  from  the  second  cervical  nerve,  and  is 
occasionally  double.  It  ascends  along  the  posterior  border  of  the 
sterno-mastoid  muscle  to  the  occiput,  where  it  supplies  the  back  of  the 
scalp,  and  communicates  with  the  great  occipital,  the  great  auricular, 
and  the  posterior  auricular  nerves.  It  also  sends  off  one  branch,  which 
is  distributed  to  the  skin  of  the  temporal  region,  and  another  auricular 
to  the  pinna  of  the  ear.  Beneath  the  sterno-mastoid  this  nerve  com- 
monly forms  a  loop,  which  embraces  the  nervus  accessorius,  and  sends 
a  branch  to  it. 

The  superficial  cervical  n.  comes  from  the  second  and  third  cervical 
nerves.  It  passes  transversely  forwards  over  the  sterno-mastoid  muscle, 
and  supplies  the  front  of  the  neck.  Some  of  its  filaments  ascend 
towards  the  jaw,  and  join  the  cervical  branch  of  the  facial  nerve  ;  other 
filaments  descend  and  supply  the  skin  in  front  of  the  neck  as  low  as 
the  sternum. 

The  descending  or  supra-clavicular  branches  are  derived  from  the 
third  and  fourth  cervical  nerves,  and  divide  into  three  branches,  which 
cross  over  the  clavicle,  and  supply  the  skin  of  the  front  of  the  chest  and 
shoulder.  Of  these,  one,  called  the  internal  or  sternal,  supplies  the  skin 


DEEP    CERVICAL    FASCIA.  69 

over  the  inner  end  of  the  clavicle  and  the  upper  part  of  the  sternum  ; 
another,  the  middle  or  claviciilar,  passes  over  the  middle  of  the  clavicle, 
and  is  distributed  to  the  skin  over  the  pectoral  muscle,  the  mammary 
gland,  and  the  nipple  ;  the  third,  named  external  or  acromial,  crosses 
over  the  trapezius  and  acromion  to  supply  the  skin  of  the  shoulder. 

Reviewing  these  cutaneous  branches  of  the  cervical  plexus,  we 
find  that  they  have  a  very  wide  distribution,  for  they  supply  the 
skin  covering  the  following  parts — viz.,  the  ear,  the  back  of  the 
scalp,  the  side  of  the  cheek,  the  parotid  gland,  the  front  and  side 
of  the  neck,  the  upper  and  front  part  of  the  chest  and  shoulder. 

CERVICAL  Look  for  this  branch  beneath  the  fascia  near 

BRANCH  OF  THE  the  angle  of  the  jaw  (p.  66).  It  leaves  the 
FACIAL  NERVE.  parotid  gland,  and,  piercing  the  deep  cervical 
fascia,  divides  into  filaments  which  curve  forwards  below  the  jaw ; 
some  of  these,  forming  arches,  join  the  superficial  cervical  branch 
of  the  cervical  plexus  ;  others  supply  the  platysma  and  skin. 

DEEP  CERVICAL          Now  turn  your  attention  to  the  membranous 
FASCIA.  investment  called  the  deep  cervical  fascia,  which 

encloses  the  several  structures  of  the  neck.  In  some  subjects  the 
fascia  is  very  thin  ;  in  others,  with  strong  muscles,  it  is  proportion- 
ally dense  and  resisting.  It  is  always  stronger  in  particular  situa- 
tions, for. the  more  effective  protection  of  the  parts  beneath ;  for 
instance,  in  front  of  the  trachea,  in  the  fossa  above  the  clavicle, 
and  below  the  angle  of  the  jaw.  It  not  only  covers  the  soft  parts 
of  the  neck  collectively,  but,  by  its  inflections,  forms  separate 
sheaths  for  the  muscles,  vessels,  and  glands.  It  isolates  them,  and 
keeps  them  in  their  proper  relative  position.  A  lengthened  de- 
scription of  its  numerous  layers  would  be  not  only  extremely 
tedious,  but  unintelligible,  without  considerable  knowledge  of  the 
anatomy  of  the  neck.  We  propose,  therefore,  to  give  only  a  gene- 
ral outline  of  the  fascia,  and  of  its  principal  layers,  commencing 
from  behind. 

Tracing  it  from  behind,  we  find  that  the  cervical  fascia  (some- 
times called  deep  cervical  or  muscular  fascia  of  the  neck)  is  attached 
to  the  ligamentum  nuchas  and  to  the  spinous  and  transverse  pro- 
cesses of  the  cervical  vertebrae.  From  these  attachments  it  passes 
forwards  over  the  posterior  triangle  of  the  reck  to  the  posterior 


70  DEEP   CERVICAL   FASCIA. 

border  of  the  sterno-mastoid,  where  it  splits  into  two  layers,  super- 
ficial and  deep,  which  invest  that  muscle  and  reunite  at  its  an- 
terior border.  The  superficial  layer  passes  towards  the  mesial  line, 
where  it  becomes  continuous  with  the  corresponding  fascia  of  the 
opposite  side.  The  layer  which  lies  in  front  of  the  sterno-mastoid 
is  attached  above  to  the  base  of  the  inferior  maxilla,  and  passes 
over  the  parotid  gland  to  the  zygoma,  to  the  mastoid  process,  and 
the  superior  curved  line  of  the  occipital  bone.  Traced  downwards, 
we  find  it  attached  to  the  clavicle  and  to  the  upper  border  of  the 
sternum.  In  the  middle  line  it  is  closely  connected  to  the  hyoid 
bone,  and  below  the  thyroid  body  divides  into  two  layers,  one 
being  attached  to  the  front  of  the  upper  border  of  the  sternum,  the 
other  to  the  back  of  the  upper  border  of  the  same  bone.  Between 
these  layers  there  is  a  well-marked  interval,  containing  more  or 
less  fat,  and  one  or  two  small  lymphatic  glands.  This  layer  forms 
investing  sheaths  for  the  depressor  muscles  of  the  os  hyoides  and 
larynx. 

The  deep  layer — viz.,  that  which  passes  beneath  the  sterno- 
mastoid — forms  the  common  sheath. for  the  carotid  artery,  internal 
jugular  vein,  and  the  pneumogastric  nerve,  which  lie  behind  this 
muscle ;  the  structures  contained  in  the  carotid  sheath  are  separated 
from  each  other  by  delicate  septa.  The  fascia  is  continued  behind 
the  pharynx  (constituting  the  prcevertebral  fascia)  to  join  the  fascia 
of  the  opposite  side,  wrhile  another  prolongation  passes  in  front 
of  the  trachea  beneath  the  sterno-thyroid  muscle.  Below,  it  is 
attached  to  the  first  rib,  to  which  it  binds  down  the  intermediate 
tendon  of  the  omo-hyoid ;  and  still  further  down  it  is  continuous 
in  the  chest  with  the  pericardium.  It  may  also  be  traced  under 
the  clavicle  along  the  axillary  vessels  and  nerves  into  the  axilla. 
Above,  it  is  attached  to  the  angle  of  the  lower  jaw,  from  which  it 
extends  backwards  to  the  styloid  process,  and  forms  the  sti/lo- 
maxillary  ligament.  Thence  it  is  attached  to  the  base  of  the  skull, 
the  petrous  portion  of  the  temporal  bone,  and  the  basilar  process  of 
the  occipital  bone. 

A  correct  knowledge  of  the  attachments  of  the  principal  layers 
of  the  cervical  fascia  is  essential  to  a  right  understanding  of  the 
course  which  pus  takes  when  it  forms  in  the  neck.  For  instance, 


STERNO-CLEIDO-MASTOIDEUS.  71 

suppose  the  pus  to  be  formed  at  the  lower  part  of  the  neck.  If  it 
be  seated  under  the  superficial  layer  (which  is  attached  to  the 
clavicle),  it  may  burrow  beneath  the  clavicle  into  the  axilla.  But 
if  it  be  seated  beneath  the  deep  layer  (which  is  attached  to  the 
first  rib),  then  it  becomes  more  serious,  since  the  pus  may  travel 
through  the  loose  tissue  by  the  side  of  the  pharynx,  and  make  its  way 
into  the  chest,  where  it  may  burrow  down  the  anterior  or  the  posterior 
mediastinum,  and  burst  into  the  trachea  or  the  oesophagus. 

Besides  forming  sheaths  for  the  several  structures  of  the  neck, 
there  are  other  purposes  to  which  the  cervical  fascia  is  subservient. 
The  firm  attachment  of  its  layers  to  the  sternum,  the  first  rib,  and 
the  clavicle,  forms  a  fibrous  barrier  at  the  upper  opening  of  the 
chest,  which  supports  the  soft  parts,  and  prevents  their  yielding  to 
the  pressure  of  the  atmosphere  during  inspiration.  Dr.  Allan  Burns1 
first  pointed  out  this  important  function  of  the  cervical  fascia,  and 
has  recorded  a  case  exemplifying  the  results  of  its  destruction  by 
disease. 

Moreover,  the  great  veins  at  the  root  of  the  neck,  namely,  the 
internal  jugular,  subclavian,  and  innominate,  are  so  closely  united 
by  the  cervical  fascia  to  the  adjacent  bones  and  muscles,  that  when 
divided  they  gape.  They  are,  as  the  French  express  it,  '  canalisees,' 
and  are  therefore  better  able  to  resist  the  pressure  of  the  atmosphere, 
which  tends  to  render  them  flaccid  and  impervious  during  inspira- 
tion. But  this  anatomical  disposition  of  the  great  veins  makes 
them  more  liable  to  the  entrance  of  air  when  wounded.  Instances 
of  death  have  been  recorded,  resulting  from  the  sudden  entrance  of 
air  into  the  veins  during  operations  about  the  neck,  or  even  the 
axilla. 

STEKNO-CLEIDO-          The  sterno-cleido-mastoideus  is  the  large  muscle 
MASTOIDEUS.  which  passes  obliquely  across  the  neck.     It  arises 

by  a  rounded  tendon  from  the  upper  part  of  the  sternum,  and  by 
fleshy  fibres  from  the  sternal  third  of  the  clavicle.  It  is  inserted 
by  a  thick  tendon  into  the  external  surface  of  the  mastoid  process, 
and  by  a  thin  aponeurosis  into  about  the  outer  half  of  the  superior 
curved  ridge  of  the  occipital  bone. 

The  sternal  origin  of  the  muscle  is  at  first  separated  from  the 
1  Surgical  Anatomy  of  the  Head  and  Neck. 


72  TRIANGLES   OF   THE   NECK. 

clavicular  by  a  slight  interval ;  subsequently  the  sternal  fibres 
gradually  overlap  the  clavicular.  The  muscle  is  confined  by  its 
strong  sheath  of  fascia,  in  such  a  manner  that  it  forms  a  slight 
curve,  with  the  convexity  forwards.  Observe  especially  that  its 
front  border  overlaps  the  common  carotid  artery;  along  this 
border  we  make  the  incision  in  the  operation  of  tying  the  vessel. 

ACTION  OF  When  both  sterno-mastoids  act  simultaneously 

STERNO-MASTOID.  they  draw  the  head  and  neck  forwards  and  down- 
wards, and  are  therefore  especially  concerned  in  raising  the  head 
from  the  recumbent  position.  When  one  sterno-mastoid  acts 
singly,  it  turns  the  head  obliquely  towards  the  opposite  shoulder  ;  in 
this  action  it  co-operates  with  the  splenius  of  the  other  side.1  On 
emergency,  the  sterno-mastoid  acts  as  a  muscle  of  inspiration,  by 
raising  the  sternum  ;  its  fixed  point  being,  in  this  case,  at  the  head. 
The  sterno-mastoid  is  supplied  by  three  nutrient  arteries — an 
upper,  a  middle,  and  a  lower.  The  upper  sterno-mastoid  artery,  a 
branch  of  the  occipital,  enters  the  muscle  with  the  n.  accessorius, 
close  to  the  mastoid  process  of  the  temporal  bone ;  the  middle 
mastoid  is  a  branch  of  the  superior  thyroid,  and  enters  the  under 
surface  of  the  muscle,  crossing  over  the  common  carotid  on  a  level 
with  the  thyroid  cartilage  ;  the  lower  mastoid  is  a  branch  of  the 
supra-scapular,  and  supplies  the  clavicular  portion  of  the  muscle, 
close  to  its  origin. 

The  sterno-mastoid  is  supplied  with  nerves  by  the  n.  accessorius, 
and  by  branches  from  the  deep  cervical  plexus :  these  branches  come 
from  the  second  and  sometimes  the  third  cervical  nerves. 

TBIANGLES  OF  Anatomists   avail    themselves   of    the    oblique 

THE  NECK.  direction  of  the  sterno-mastoid  muscle  to  divide 

the  neck  on  each  side  into  two  great  triangles,  an  anterior  and  a 
posterior  (fig.  25).  The  base  of  the  anterior  triangle  is  formed  by 
the  jaw,  its  sides  by  the  mesial  line  and  the  front  border  of  the 
sterno-mastoid.  The  posterior  has  the  clavicle  for  the  base,  while 

1  The  single  action  of  the  muscle  is  well  seen  when  it  becomes  rigid  and  causes 
a  wry-neck.  Other  means  of  relief  failing,  the  division  of  the  muscle  near  its 
origin  is  sometimes  beneficial  in  curing  the  distortion.  In  deciding  as  to  the  pro- 
priety of  this  operation,  we  should  be  careful  to  examine  the  condition  of  the  other 
muscles,  lest,  after  having  divided  the  sterno-mastoid,  we  should  be  disappointed 
in  removing  the  deformity. 


CONTENTS   OF   THE   POSTEKIOR   TRIANGLE.  73 

the  sides  are  defined  by  the  hind  border  of  the  sterno-mastoid,  and 
the  front  border  of  the  trapezius. 

The  omo-hyoid  muscle,  which  crosses  the  neck  under  the 
sterno-mastoid,  subdivides  these  primary  triangles  into  four  smaller 
ones  (fig.  25)  of  unequal  size  :  an  anterior  superior,  an  anterior  in- 
ferior, a  posterior  superior,  and  a  posterior  inferior.  The  direction 

FIG.  25. 


N.  accessorius  .  . 

Digastricus   .  .  . 

Os  hyoides     .  .  . 

Omo-hyoideus  .  . 


Sterno-mastoid 
muscle  drawn  aside. 

Splenius  capitis. 


—  Levator  anguli  sca- 
pulae. 

Scalenus  medius. 


Scalenus  anticus. 


DIAGRAM  OF  TRIANGLES  OF  THE  NECK. 


1.  Superior  carotid  triangle. 

2.  Inferior       „         „ 

3.  Occipital  triangle. 


4.  Supra-clavicular  triangle. 

5.  Snbmaxillary  triangle. 


of  the  omo-hyoid  muscle  renders  their  boundaries  at  once  obvious. 
CONTENTS  OF  The  fat  and  connective  tissue  must  now  be  care- 

POSTERIOR  fully  removed  from  the  posterior  triangle.     The 

TRIANGLE.  following  muscles  will  be  seen  forming  its  floor : 

viz.,  beginning  from  above,  the  splenius  capitis,  the  levator  anguli 
scapulae,  the  scalenus  medius  and  posticus,  and  a  small  portion  of 
the  serratus  magnus.  The  posterior  belly  of  the  omo-hyoid  crosses 
this  triangle  about  an  inch  above  the  clavicle,  and  subdivides  it 
into  two  unequal  parts — an  upper  or  occipital,  and  a  lower  or  supra- 
clavicular.  In  the  occipital  triangle,  the  larger  of  the  two,  besides 


74  NERVUS   ACCESSORIUS. 

the  muscles  just  mentioned  (with  the  exception  of  the  serratus 
magnus),  are  found  the  descending  branches  of  the  cervical  plexus  ; 
and,  passing  obliquely  downwards  from  beneath  the  sterno-mastoid 
is  the  spinal  accessory  nerve,  which  enters  the  under  part  of  the 
trapezius.  Curving  round  the  posterior  border  of  the  sterno- 
mastoid,  and  becoming  superficial,  are  the  ascending  and  transverse 
branches  of  the  superficial  cervical  plexus.  The  transversalis  colli 
(posterior  scapular)  artery  and  vein,  and  its  branch  the  superficialis 
colli  (which  chiefly  supplies  the  trapezius),  cross  transversely  out- 
wards the  lower  part  of  the  space.  A  chain  of  lymphatic  glands 
is  also  found  along  the  posterior  border  of  the  sterno-mastoid. 

NERVUS  The  upper  part  of  the  sterno-mastoid  is  traversed 

ACCESSOKIUS.  obliquely  by  a  large  nerve  called  the  spinal  acces- 

sory or  n.  accessorius.  This  nerve — the  eleventh  cranial — consists 
of  two  parts  :  one,  the  accessory,  arises  from  the  side  of  the  medulla 
oblongata  below  the  pneumogastric  nerve;  the  other,  the  s.pinal 
part,  arises  from  the  cervical  portion  of  the  spinal  cord  by  a  series 
of  filaments  from  the  lateral  tract  as  low  down  as  the  sixth  cervical 
vertebra.  The  spinal  portion  ascends  between  the  ligamentum 
denticulatum  and  the  posterior  roots  of  the  spinal  nerves,  through 
the  foramen  magnum  into  the  skull.  Within  the  cranium  the  two 
parts  unite  and  form  a  single  nerve,  which  leaves  the  skull  through 
the  foramen  jugulare.  Here  the  accessor//  portion  is  connected 
with  the  ganglion  of  the  root  of  the  pneumogastric  by  several 
filaments ;  and  lower  down  it  again  joins  the  pneumogastric  at  the 
ganglion  of  the  trunk,  below  which  the  two  nerves  become  blended. 
The  accessory  and  spinal  portions  communicate  in  the  foramen 
jugulare.  Below  the  foramen  the  spinal  part  runs  behind  the 
internal  jugular  vein,  the  digastric  and  stylo-hyoid  muscles,  and 
then  pierces  obliquely  the  upper  third  of  the  sterno-mastoid. 
Emerging  beneath  its  outer  border,  it  crosses  the  posterior  triangle 
of  the  neck  to  the  under  surface  of  the  trapezius,  to  which  it  is 
distributed.  The  nervus  accessorius  supplies  also  the  sterno- 
mastoid  in  its  passage  through  it,  and  here  it  joins  some  branches 
from  the  third  cervical.  After  leaving  the  muscle  it  is  joined  by 
branches  from  the  second  and  third  cervical  nerves.  Beneath  the 
trapezius  it  forms  a  plexus  with  the  third  and  fourth  cervical 


SUPRA-CLAVICULAR   TRIANGLE.  75 

nerves.  The  upper  mastoid  artery,  a  branch  of  the  occipital,  enters 
the  sterno-mastoid  with  the  nerve. 

SUPRA-CLAVICU-  The  supra-clavicular   or   subclavian  triangle  is 

IAR  TRIANGLE,  bounded  below  by  the  clavicle,  in  front  by  the 
outer  border  of  the  sterno-niastoid,  and  above  by  the  posterior 
belly  of  the  omo-hyoid  muscle.  The  area  of  the  triangle  thus 
formed  will  vary  in  proportion  to  the  obliquity  of  the  omo-hyoid 
muscle,  and  the  extent  to  which  the  sterno-mastoid  and  trapezius 
are  attached  to  the  clavicle.  The  depth  of  the  vessels  and  nerves 
contained  in  this  space  depends,  not  only  upon  the  degree  to 
which  the  clavicle  arches  forwards,  but  varies  with  the  elevation 
and  depression  of  the  shoulder. 

The  descending  branches  of  the  cervical  plexus, 
together  with  some  fat,  should  now  be  cut  through 
and  turned  aside,  when  a  layer  of  a  fascia  which  binds  down  the 
omo-hyoid  muscle  to  the  clavicle  will  be  exposed.  Beneath  this 
is  a  deeper  layer  of  fascia,  which  covers  the  subclavian  vessels  and 
brachial  plexus  of  nerves,  and  descends  with  them  under  the  clavicle 
into  the  axilla.  Between  these  two  layers  we  meet  with  more  or 
less  fat  and  connective  tissue  and  lymphatic  glands  continuous 
with  those  in  the  axilla.  It  will  be  easily  understood  how  a 
collection  of  pus  in  the  axilla  may  ascend  in  front  of  the  vessels 
and  point  above  the  clavicle,  or,  vice  versa,  how  matter  formed  in 
the  neck  may  travel  under  the  clavicle  and  point  in  the  axilla. 

Near  the  posterior  border  of  the  sterno-mastoid  muscle  the 
external  jugular  vein  passes  through  both  layers  of  the  deep  fascia, 
and  terminates  in  the  subclavian  ;  but  before  its  termination  it  is 
commonly  joined  by  the  supra-scapular,  the  posterior  scapular,  and 
other  unnamed  veins  proceeding  from  the  surrounding  muscles ;  so 
that  there  is  in  this  situation  a  confluence  of  veins,  which,  when 
large  or  distended,  is  exceedingly  embarrassing. 

The  fascia  and  the  glands  should  be  removed,  and  the  following 
objects  carefully  dissected.  Behind  and  nearly  parallel  with  the 
clavicle  is  the  supra-scapular  (transversalis  humeri)  artery,  a  branch 
of  the  thyroid  axis.  A  little  higher  is  the  transversalis  colli,  or 
posterior  scapular  (commonly  a  branch  of  the  thyroid  axis),  which 
crosses  the  lower  part  of  the  neck  towards  the  posterior  superior 


76  ANTERIOR   TRIANGLE. 

angle  of  the  scapula.  Both  these  arteries  are  very  irregular  in 
respect  to  their  origin,  the  last  particularly  being  often  given  off 
from  the  subclavian  in  the  third  part  of  its  course.  Search  for  the 
outer  border  of  the  scalenus  anticus,  which  descends  from  the 
transverse  processes  of  the  cervical  vertebree  to  the  first  rib  :  run- 
ning down  longitudinally  upon  it  may  be  seen  the  phrenic  nerve. 
The  subclavian  vein  lies  upon  the  first  rib  in  front  of  the  insertion 
of  the  anterior  scalene  muscle  behind  the  clavicle,  so  that  it  is  not 
usually  seen  in  this  triangle.  The  subclavian  artery  rises  up  into- 
the  neck  as  high  as  an  inch  above  the  clavicle,  and  sometimes  on 
the  right  side  as  high  as  an  inch  and  a  half.  It  appears  higher 
than  the  vein,  emerging  beneath  the  outer  border  of  the  scalenus 
anticus,  and  care  must  be  taken  to  preserve  the  small  branch  from 
the  brachial  plexus,  which  crosses  the  artery  and  proceeds  to  the 
subclavius  muscle.  The  large  nerves  constituting  the  brachial 
plexus  come  out  between  the  scalenus  anticus  and  medius,  higher 
than  the  subclavian  artery,  and  on  a  plane  posterior  to  that  vessel. 
These  different  objects  will  be  described  in  detail  hereafter. 

DISSECTION  OF  Tne   anterior  triangle  must  now  be  dissected. 

THE  ANTERIOR          In  doing  so,  notice,  before  the  deep  cervical  fascia 
TRIANGLE.  \^  removed,  the  arching  forwards  of  the  anterior 

border  of  the  sterno-mastoid  muscle,  which  is  connected  to  the 
lower  jaw  by  the  fascia,  so  that  the  common  carotid  artery  is 
concealed  from  view  before  the  parts  are  disturbed.  The  anterior 
triangle  is  bounded  behind  by  the  anterior  border  of  the  sterno- 
mastoid,  in  front  by  the  middle  line  of  the  neck,  and  above  by  the 
lower  border  of  the  inferior  maxilla.  Covering  the  triangle  are  the 
superficial  and  deep  cervical  fascias,  and  the  platysma ;  passing 
across  it  are  the  superficial  cervical  n.,  the  infra-maxillary  branch 
of  the  facial  nerve  ;  and  descending  in  front  is  the  anterior  jugular 
vein.  This  space  is  subdivided  by  the  anterior  belly  of  the  omo- 
hyoid  into  a  superior  and  an  inferior  carotid  triangle,  and  above 
them  is  a  third  triangle  mapped  out  by  the  converging  bellies  of 
the  digastric  muscle  arid*  the  lower  jaw,  and  is  called  the  sub- 
maxillary  or  digastric  triangle  (fig.  25,  p.  73). 

The  inferior  carotid  triangle  is  bounded  above  and  below  by 
the   omo-hyoid  and  sterno-mastoid  muscles,  and  in  front  by  the 


STERNO-HYOID   MUSCLE.  77 

middle  line.  The  muscles  forming  its  floor  are  the  sterno-hyoid 
and  sterno-thyroid  muscles,  and  lying  on  them  is  the  anterior 
jugular  vein;  in  the  middle  line  is  the  thyroid  body  covering  the 
trachea.1 

The  superior  carotid  triangle  has  for  its  boundaries  the  sterno- 
mastoid,  the  omo-hyoid,  and  the  posterior  belly  of  the  digastricus. 
Its  muscular  floor  is  formed  by  the  hyo-glossus,  the  middle  and 
inferior  pharyngeal  constrictors,  and  the  thyro-hyoid.  In  this 
space  are  found  the  bifurcation  of  the  common  carotid  into  its 
external  and  internal  divisions,  and  the  following  branches  of  the 
external  carotid — the  superior  thyroid,  lingual,  facial,  the  occipital, 
and  the  ascending  pharyngeal  .arteries — their  accompanying  veins 
and  the  internal  jugular  vein.  The  nerves  seen  are  the  hypoglossal, 
crossing  over  the  external  carotid,  the  infra-maxillary  branch  of 
the  facial,  the  spinal  accessory,  the  superior  and  external  laryngeal 
nerves,  and  in  front  of  the  carotid  sheath  is  the  descendens  noni. 

The  digastric  triangle  will  be  described  subsequently  (p.  91). 

Now  examine  the  flat  muscles  in  front  of  the  neck,  which  pull 
down  the  larynx  and  os  hyoides — namely,  the  sterno-hyoid,  sterno- 
thyroid,  omo-hyoid,  and  thyro-hyoid.2  Remove  the  fascia  which 
covers  them,  disturbing  them  as  little  as  possible,  and  take  care  of 
the  nerves  (branches  of  the  descendens  noni),  which  enter  their 
outer  borders. 

The  sterno-hyoid  arises  from  the  back  part  of 
STEENO-HYOID.       ,  ,  .  ,      .      .       ,. 

the  sternum  and  posterior  sterno-clavicular  liga- 
ment, from  the  clavicle  and  occasionally  from  the  cartilage  of  the 
first  rib,  and  is  inserted  into  the  lower  border  of  the  body  of  the  os 
hyoides.  This  is  the  most  superficial  of  the  muscles  in  front  of 
the  neck.  We  cut  in  the  mesial  line  between  these  muscles  in 
laryngotomy. 

STEKNO-  The  sterno-thyroid  arises  from  the  back  part  of 

THYROID.  the  sternum,  below  and  internal  to  the  origin  of 

1  The  vessels  and  nerves  lying  within  and  upon  the  carotid  sheath  are  not  seen, 
as  they  are  situated  beneath  the  anterior  border  of  the  sterno-mastoid . 

*  The  sterno-hyoid  and  sterno-thyroid  muscles  often  present  slight  transverse 
tendinous  lines.  These  tendinous  intersections  are  quite  rudimentary  in  man  ;  but 
in  some  animals  with  long  necks,  e.g.  the  giraffe,  they  are  so  developed  that  each 
depressor  muscle  is  composed  of  alternations  of  muscle  and  tendon. 


78 


CENTRAL    LINE    OF   THE    NECK. 


the  sterno-hyoid,  and  the  cartilage  of  the  first  rib,  and  is  inserted 
into  the  oblique  ridge  on  the  ala  of  the  thyroid  cartilage.  This 
muscle  is  situated  immediately  under,  and  is  much  broader  than, 
the  sterno-hyoid. 

FIG.  26. 


Digastricus. 


Occipital  a.    . 

Hypoglossal  11 . 
Descender)  s 
noni  n.    .    . 


2nd  cervical  n. 
Superior  thy- 
roid a.     .    . 


3rd  cervical  n. 

Communicans 

noni  n.    .    . 

Crico- thyroid  m 
Internal  jugu- 
lar v.       .    . 
Common  caro- 
tid a.       .    . 


Cricoid  cartilage. 

Isthmus  of 
thyroid  gland. 


Trachea. 


Inferior 
thyroid  v. 


CENTRAL  LINE    OF   NECK. — COUKSE   AND    RELATIONS   OF   COMMON   CAROTID   ABTEBY. 

The  two  sterno-hyoid  muscles  converge  as  they  ascend  to  their 
insertions,  and  opposite  the  cricoid  cartilage  and  the  two  or  three 
tipper  rings  of  the  trachea  they  are  in  contact  with  one  another. 


DEPRESSOR  MUSCLES   OF   THE   LARYNX.  79 

The  sterno-thyroid,  however,  diverge  to  their  insertions,  but  are  in 
contact  below,  the  result  of  which  is  that  the  trachea  is  completely 
covered  in  front  by  muscular  fibres. 

The  omo-hyoid  consists  of  two  fleshy  portions 
OMO-HYOID.  .,,  ,  T          .         ,, 

connected  by  a  tendon.     It  arises  from  the  upper 

border  of  the  scapula,  and  sometimes  from  the  ligament  over  the 
notch,  and  is  inserted  into  the  lower  border  of  the  body  of  the  os 
hyoides  just  external  to  the  sterno-hyoid.  From  the  scapula  it 
comes  nearly  horizontally  forwards  across  the  lower  part  of  the 
neck,  and  passes  beneath  the  sterno-mastoid,  over  the  sheath  of  the 
great  vessels  of  the  neck  on  a  level  with  the  cricoid  cartilage;  then, 
changing  its  direction,  it  ascends  nearly  vertically  close  to  the 
outer  border  of  the  sterno-hyoid.  Thus  the  muscle  does  not 
proceed  straight  from  origin  to  insertion,  but  forms  an  obtuse 
angle  beneath  the  sterno-mastoid  muscle.  The  intermediate 
tendon  is  situated  at  the  angle  and  is  bound  down  to  the  first  rib 
and  the  sternum  by  a  process  of  the  deep  cervical  fascia.  The 
object  of  this  peculiar  direction  of  the  omo-hyoid  appears  to  be  to 
keep  tense  that  part  of  the  cervical  fascia  which  covers  the  apex  of 
the  pleura,  and  thus  to  resist  atmospheric  pressure. 

EELATIONS  OF  At  its  origin  the  omo-hyoid  is  covered  by  the 

THE  OMO-HYOID.  trapezius,  then  by  the  clavicle  and  subclavius,  and 
lastly,  by  the  sterno-mastoid  and  platysma  myoides.  It  lies  on  the 
scalenus  medius  and  anticus,  the  brachial  plexus,  the  phrenic  nerve, 
then  on  the  internal  jugular  vein,  pneumogastric  nerve  and  common 
carotid  artery  enclosed  within  their  common  sheath,  on  the  descen- 
dens  noni,  the  sterno-thyroid,  and  thyro-hyoid  muscles. 

These  depressor  muscles  are  all  supplied  with  nerves  (fig.  26, 
p.  78)  by  the  descendens  noni  (a  branch  of  the  twelfth  or  hypo- 
glossal),  and  by  the  communicantes  noni  (branches  of  the  second 
and  third  cervical  nerves).  The  descendens  noni  sends  a  separate 
branch  to  each  belly  of  the  omo-hyoid.  They  are  supplied  with 
blood  by  the  superior  and  inferior  thyroid  arteries. 

The  thyro-hyoid  arises  from  the  oblique  line  on 
THYKO-HYOID.          .,        ,        .;,,      _:,         . -,         ,.,  -.  ,     , 

the  ala  of  the  thyroid  cartilage,  and  runs  up  to  be 

inserted  into  the  lower  border  of  the  body  and  the  inner  half  of  the 
great  cornu  of  the  Kyoid  bone.  This  muscle  is  a  continuation  of 


80  PARTS   BENEATH   THE   STERNO-MASTOID. 

the  ster no-thyroid.  It  is  supplied  by  a  special  branch  of  the  hypo- 
glossal  nerve  which  enters  the  muscle  close  by  its  posterior  border, 
in  company  with  the  hyoid  branch  of  the  lingual  artery.  In  front 
of  the  muscle,  are  the  omo-hyoid  and  sterno-hyoid  muscles,  and  it 
covers  the  thyro-hyoid  membrane,  the  thyroid  cartilage,  and  the 
superior  laryngeal  vessels  and  nerve  as  they  enter  the  larynx. 

ACTION  OF  THE  The    sterno-hyoid,    sterno-thyroid,    omo-hyoid, 

DEPKESSOB  and  thyro-hyoid  muscles  co-operate  in  fixing  the 

MUSCLES.  larynx  and  os  hyoides,  e.g.,  in  sucking,  or  they 

depress  the  larynx  after  it  has  been  raised  in  deglutition.  Again, 
they  depress  it  in  the  utterance  of  low  notes.  That  the  larynx  is 
raised  or  depressed,  according  to  the  height  of  the  note,  may  be 
ascertained  by  placing  the  finger  on  it  while  singing  through  an 
octave.  The  omo-hyoid,  in  addition,  is  a  tensor  of  the  cervical 
fascia,  and  draws  down  the  hyoid  bone  to  its  own  side.  The  thyro- 
hyoid  depresses  the  hyoid  bone,  or  elevates  the  thyroid  cartilage, 
according  as  the  one  or  the  other  is  the  fixed  point. 

The  sterno-mastoid  muscle  must  now  be  cut 
transversely  through  the  middle,  and  the  two  ends 
turned  upwards  and  downwards,  so  that  they  may  be  replaced  if 
necessary.  This  done,  notice  the  strong  layer  of  fascia  which  lies 
under  the  muscle  and  forms  part  of  its  sheath.  It  is  attached  to 
the  angle  of  the  jaw,  thence  descends  over  the  large  vessels  of  the 
neck,  and  is  firmly  connected  to  the  clavicle  and  first  rib.  This 
fascia  prevents  matter  coming  to  the  surface,  when  suppuration 
takes  place  by  the  side  of  the  pharynx. 

Remove  the  fascia,  and  clean  the  various  structures  beneath  the 
sterno-mastoid,  taking  care  not  to  cut  away  the  descendeiis  noni 
and  communicantes  noni  nerves,  which  lie  in  front  of  the  sheath  of 
the  common  carotid.  Dissect  out  the  lymphatic  glands  which  lie 
along  the  sheath  of  the  large  vessels. 

PAKTS  EXPOSED          The  objects  exposed  to  view,  when  the  muscle  is 
BENEATH  THE  reflected,  are  very  numerous.     Among  these  the 

STEKNO-MASTOID.  mOre  important  are  :  the  sterno-clavicular  articu- 
lation, the  splenius  capitis  and  colli,  the  posterior  belly  of  the  di- 
gastricus,  the  levator  anguli  scapulae,  scalenus  medius  and  anticus, 
omo-hyoid,  sterno-hyoid,  and  sterno-thyroid  muscles  ;  the  occipital 


COMMON   CAROTID    ARTERY.  81 

artery,  the  common  carotid  artery  and  its  division,  the  internal 
jugular  vein,  the  subclavian  artery  and  the  branches  of  the  first 
part  of  its  course,  the  cervical  plexus,  and  the  lower  cervical  nerves 
which  form  the  brachial  plexus ;  the  phrenic,  pneumogastric, 
hypoglossal,  and  spinal  accessory  nerves,  the  descendens  and  com- 
municantes  noni  nerves ;  the  subclavian  vein  and  its  tributaries  ; 
and  lastly,  a  small  part  of  the  parotid  gland,  and  the  three  sterno- 
mastoid  arteries.  On  the  left  side,  in  addition,  we  find  the  thoracic 
duct ;  on  the  right  side,  the  right  lymphatic  duct. 

COURSE  AND  RELA-       The  common  carotid  artery  is  now  exposed  in 
TIONS  OF  THE  the  whole  extent  of  its  course  in  the  neck.     It 

COMMON  CABOTID.  arises,  on  the  right  side  from  the  arteria  innomi- 
nata,  behind  the  upper  part  of  the  right  sterno-clavicular  articula- 
tion ;  on  the  left,  from  the  arch  of  the  aorta.  It  ascends  in  front 
of  the  bodies  of  the  cervical  vertebrae,  by  the  side  of  the  trachea, 
thyroid  gland,  and  larynx,  as  high  as  the  upper  border  of  the 
thyroid  cartilage,  and  then  divides  into  the  external  and  internal 
carotids.  Thus,  a  line  drawn  from  the  sternal  end  of  the  clavicle 
to  a  point  midway  between  the  mastoid  process  and  the  angle  of 
the  jaw,  will  nearly  indicate  its  course.  It  is  contained  in  a 
sheath  of  the  deep  cervical  fascia,  together  with  the  internal 
jugular  vein  and  the  pneumogastric  nerve.  The  vein  lies  on  the 
outer  side  of,  and  parallel  with,  the'  artery ;  the  nerve  lies  behind 
and  between  the  artery  and  the  vein.  The  structures  contained 
within  this  sheath  are  separated  from  each  other  by  a  thin  septum 
of  fascia,  so  that  each  has  a  separate  investment.  Owing  to  the 
increasing  breadth  of  the  larynx,  the  two  common  carotid  arteries, 
which  at  their  origin  lie  near  together,  are  separated  by  a  wide 
interval  at  their  point  of  division. 

At  the  lower  part  of  the  neck  the  carotid  artery  is  deeply 
placed,  but  as  it  ascends  it  becomes  more  superficial,  although  it 
has  the  appearance  of  being  deeply  situated  owing  to  the  promi- 
nence of  the  thyroid  cartilage.  In  front  the  artery  is  covered  by 
the  skin,  superficial  fascia,  platysma  myoides,  deep  fascia,  the 
sternal  portion  of  the  sterno-mastoid,  the  sterno-hyoid,  and  thyroid 
muscles,  and,  on  a  level  with  the  cricoid  cartilage,  it  is  crossed  by 
the  omo-hyoid.  Above  this  point  the  artery  becomes  more  super- 

G 


82  RELATIONS   OF   THE   COMMON   CAROTID  ARTERY. 

ficial,  and  is  covered  by  the  integument,  platysma,  the  cervical 
fasciae,  the  middle  sterno-mastoid  artery,  and  only  slightly  over- 
lapped by  the  sterno-mastoid.  Lying  upon  the  sheath  of  the 
artery,  we  find  the  descendens  noni  joined  by  the  communi- 
cantes  noni  nerves.  The  sheath  is  crossed  by  the  facial,  the 
superior,  and  middle  thyroid  veins,  and  lower  down  by  the  anterior 
jugular  vein,  all  of  which  empty  themselves  into  the  internal 
jugular.  This  is  the  general  rule,  and  especial  attention  should 
be  directed  to  it,  because  the  veins  are  liable  to  be  overlooked  and 
injured  in  the  operation  of  tying  the  carotid.  To  the  inner  side 
of  the  artery  we  find  the  trachea,  the  thyroid  body,  the  recurrent 
laryngeal  nerve,  the  inferior  thyroid  artery,  the  external  laryngeal 
nerve,  the  inferior  constrictor  of  the  pharynx,  and  the  larynx.  On 
the  outer  side  are  the  pneumogastric  nerve  and  the  internal  jugu- 
lar vein.  Behind  the  artery  are  the  sympathetic  nerve,  the  inferior 
thyroid  artery,  the  recurrent  laryngeal  nerve;  and  lastly,  the 
carotid  sheath  lies  successively  upon  the  longus  colli  and  the 
rectus  capitis  anticus  major  muscles.1 

The  common  carotid  may  be  ligatured  either  above  or  below 
the  omo-hyoid.  It  is  most  accessible  above  the  point  where  this 
muscle  crosses ;  and  therefore,  if  the  surgeon  has  his  choice,  he 
would  prefer  to  tie  the  vessel  in  this  situation.  In  the  higher 
operation  we  make  an  incision,'  three  inches  in  length,  along  the 
inner  border  of  the  sterno-mastoid,  the  centre  of  the  incision  being 
opposite  the  cricoid  cartilage  :  we  cut  through  the  skin,  superficial 
fascia,  platysma,  deep  cervical  fascia,  when  we  come  to  the  anterior 
border  of  the  sterno-mastoid.  The  overlapping  edge  of  this  muscle 

1  It  is  important  that  we  should  be  aware  that  the  common  carotids  vary  occa- 
sionally in  their  origin.  Thus  the  right  may  arise  in  common  with  the  left  carotid, 
or  the  right  may  arise  separately  from  the  arch  of  the  aorta,  in  which  case  the 
right  subclavian  is  usually  transposed.  The  left  may  be  given  off  from  the  in- 
nominate artery  of  the  right  side,  or  it  may  arise  in  common  with  the  left  subclavian, 
and  thus  form  a  left  innominate.  In  transposition  of  the  aorta  there  is  a  left 
innominate,  which  is  given  off  first,  the  right  carotid  and  the  right  subclavian 
arising  as  separate  branches  from  the  arch.  The  place  of  division  of  the  common 
carotid  is  subject  to  considerable  variation  :  it  may  divide  higher  or  lower  than 
usual,  the  former  being  the  more  frequent.  Rarely  there  has  been  no  common 
carotid  artery,  the  external  and  internal  arising  as  separate  branches  from  the 
arch  of  the  aorta. 


LEFT   COMMON   CAROTID   ARTERY.  83 

must  be  drawn  outwards,  and  the  muscle  at  the  same  time  relaxed 
by  turning  the  head  to  the  same  side.  The  sheath  of  the  vessel  is 
then  exposed,  and  a  small  opening  is  to  be  made  on  its  inner  side 
large  enough  to  admit  the  aneurism  needle,  which  should  be  passed 
round  the  artery  on  its  outer  side,  so  as  to  avoid  wounding  the  in- 
ternal jugular  vein.  The  vessel  is  then  to  be  ligatured,  care  being 
taken  not  to  separate  more  of  the  sheath  than  is  necessary  from  the 
artery,  and  not  to  include  in  the  ligature  the  pneumogastric  or 
descendens  noni  nerves. 

After  ligation  of  the  artery,  the  collateral  circulation  is  main- 
tained by  the  following  vessels :  between  the  branches  of  the 
external  and  internal  carotid  arteries  of  the  opposite  side  with  the 
corresponding  branches  of  the  ligatured  side  ;  between  the  verte- 
bral and  the  posterior  communicating  of  the  same  side ;  between 
the  inferior  and  superior  thyroids  of  the  same  side ;  between  the 
profunda  cervicis  and  the  princeps  cervicis  of  the  occipital  of  the 
same  side. 
TxT  T  In  the  first  part  of  its  course  the  left  carotid 

J.N   WMAJ.   .KHi-  •*• 

SPECTS  THE  LEFT  differs  from  the  right  in  the  following  particulars  : 
CAROTID  DIFFEBS  1.  It  arises  from  the  arch  of  the  aorta,  is  there- 

FBOM  THE  BIGHT.  fore  longer  and  Deeper  seated  than  the  right,  and 
is  covered  by  the  first  bone  of  the  sternum. 

2.  It  is  crossed  by  the  left  brachio-cephalic  vein. 

3.  It  is  in  close  relation  with  the  oesophagus  and  the  trachea. 

4.  It  is  in  close  relation  with  the   left   recurrent   laryngeal 
nerve. 

5.  It  is  in  close  relation  posteriorly  with  the  thoracic  duct. 

6.  It  is  covered  by  the  thymus  gland  in  early  life. 

The  artery  has  in  front  the  sternum,  the  sterno-hyoid  and 
sterno-thyroid  muscles,  the  left  innominate  vein,  and  the  remains 
of  the  thymus  gland;  to  the  left  side  it  has  the  left  subclavian 
artery  and  the  left  pneumogastric  nerve ;  to  the  right  side  the 
arteria  innominata ;  and  behind,  the  trachea,  oesophagus,  and 
thoracic  duct. 

The  common  carotid  as  a  rule  gives  off  no  branch  in  its  course  ; 
bat,  occasionally,  the  middle  sterno-mastoid,  the  superior  thyroid, 
or,  more  rarely,  the  vertebral,  arise  from  it  prior  to  its  division. 

G    2 


84  INTERNAL  JUGULAR  VEIN. 

At  its  bifurcation  it  usually  presents  a  slight  bulbous  enlargement., 
which  is  sometimes  so  marked  that  it  might  be  mistaken  for  an 
incipient  aneurism.  It  is  necessary  to  know  that  the  carotid 
sometimes  divides  as  low  as  the  level  of  the  cricoid  cartilage,  and 
that  not  infrequently  the  division  takes  place  as  high  as  the  hyoid 
bone. 

INTERNAL  The  internal  jugular  vein  is  the  continuation  of 

JUGULAR  VEIN.  the  lateral  sinus,  and  returns  the  blood  from  the 
brain.  Leaving  the  skull  through  the  foramen  jugulare,  it  receives 
the  inferior  petrosal  sinus,  and  at  the  junction  it  presents  a  slight 
enlargement,  the  sinus.  The  vein  descends  on  the  outer  side  of  the 
internal  carotid,  and  subsequently  the  common  carotid  arteries,  in 
the  same  sheath,  and  joins  the  subclavian  vein  at  a  right  angle  to 
form  the  brachio-cephalic  or  innominate  vein.  In  its  course  down 
the  neck  it  receives  the  pharyngeal,  occipital,  facial,  lingual, 
superior,  and  middle  thyroid  veins. 

Previous  to  their  terminations  the  internal  jugular  veins  incline 
somewhat  to  the  right  side  to  meet  the  corresponding  subclavian 
veins ;  thus,  on  the  right  side,  there  is  a  triangular  interval  between 
the  artery  and  vein  in  which  is  seen  the  pneumogastric  nerve  and 
vertebral  artery ;  on  the  left  side  the  vein  slightly  overlaps  the 
artery,  thus  rendering  ligature  of  the  left  carotid  more  difficult 
than  of  the  right.  The  internal  jugular  veins  moreover  advance 
slightly  to  meet  the  subclavian  veins,  so  that  they  lie  on  a  plane  a 
little  anterior  to  their  accompanying  arteries.  A  little  before  their 
termination  the  internal  jugulars  have  a  double  valve. 
DESCENDBNS  ^ie  d'escendens  noni  (p.  92),  a  branch  of  the 

NONI  AND  COM-  hypoglossal,  runs  down  obliquely  over  the  sheath 
MUNICANTES  NONI  of  the  carotid  to  supply  the  depressor  muscles  of 
the  os  hyoides.  Trace  the  nerve  upwards  to  see 
that  it  leaves  the  hypoglossul  where  this  nerve  curves  round  the 
occipital  artery.  For  a  short  distance  the  descendens  noni  lies 
within  the  carotid  sheath  ;  but,  about  the  level  of  the  os  hyoides, 
it  comes  through  the  sheath,  and  crosses  obliquely  over  the 
carotid,  from  the  outer  to  the  inner  side.  The  descendens  noni 
is  reinforced  by  one  or  more  nerves  termed  communicantes  noni, 
derived  from  the  second  and  third  cervical  nerves.  These  com- 


THYROID    BODY.  85 

raunicating  branches  descend  on  the  outer  side  of  the  internal 
jugular  vein,  and  form  generally  two  loops  in  front  of  the  carotid 
sheath,  constituting  a  triangular  plexus  called  the  '  ansa  liypo- 
ylossi.'  From  these  loops  the  nerves  proceed  to  the  anterior  and 
posterior  bellies  of  the  omo-hyoid,  to  the  sterno-hyoid,  and  sterno- 
thyroid  muscles.  A  small  branch  may  sometimes  be  traced  pro- 
ceeding from  the  descendeiis  noni  into  the  chest  to  join  the  cardiac 
and  phrenic  nerves. 

In  some  subjects  the  descendens  noni  seems  to  be  wanting,  in 
which  case  it  will  probably  be  concealed  within  the  carotid  sheath  : 
when  this  happens  the  reinforcing  loops  from  the  cervical  nerves 
will  be  found  behind  the  internal  jugular  vein.1 

The    thyroid   body  should   now  be    examined. 

DlSSFCTION 

To  expose  it,  reflect  the  sterno-hyoid  and  thyroid 
muscles  from  their  insertions,  so  that  they  can  be  replaced  if  neces- 
sary. Next  observe  the  lymphatic  glands  of  the  neck,  and  lastly 
survey  the  objects  in  the  central  line  of  the  neck,  from  the  jaw  to 
the  sternum. 

This  very  vascular  gland-like  body  lies  over  the 

front  and  sides  of  the  upper  part  of  the  trachea, 
and  extends  upwards  on  each  side  of  the  larynx.  It  consists  of 
two  lateral  lobes,  connected  a  little  below  the  cricoid  cartilage  by 
a  transverse  portion  called  the  isthmus,  and  weighs  from  one  to 
two  ounces.  Each  lobe  is  conical,  about  two  inches  in  length, 
and  an  inch  and  a  quarter  in  breadth.  Its  base  is  opposite  the 
fifth  or  sixth  ring  of  the  trachea,  and  the  apex  by  the  side  of  the 
thyroid  cartilage.  Its  anterior  surface  is  convex,  and  is  covered 
by  the  sterno-hyoid,  sterno-thyroid,  and  omo-hyoid  muscles;  its 
deep  surface — concave — embraces  the  sides  of  the  trachea  and 
larynx,  and  usually  extends  so  far  backwards  as  to  be  in  contact 
with  the  pharynx.  Its  external  border  overlaps,  in  most  cases 
partially,  but  sometimes  completely,  the  common  carotid  artery, 

1  By  many  anatomists  the  descendens  noni  is  regarded  as  the  combination  of 
filaments  from  the  hypoglossal  and  pneumogastric  nerves  ;  by  some,  it  is  looked 
upon  as  a  branch  of  the  pneumogastric  ;  and  lastly,  which  is  most  probable,  it  is 
considered  by  others  to  be  mainly  derived  from  a  branch  which  is  sent  to  the 
hypoglossal  from  the  first  and  second  cervical  nerves. 


86  THYROID   BODY. 

particularly  on  the  right  side ;  and  there  are  instances  in  which 
the  lobe  is  deeply  grooved  by  the  vessel. 

The  isthmus  lies  over  the  second  and  third  rings  of  the  trachea. 
This  portion  of  the  organ  varies  much  in  its  dimensions.  In  some 
instances  there  is  no  transverse  portion.  This  corresponds  with 
.  the  normal  disposition  in  most  of  the  lower  orders  of  mammalia ; 
but  in  man,  it  is  a  failure  in  the  union  of  the  two  halves  by 
which  the  organ  is  originally  developed.1  Generally,  the  vertical 
measurement  is  about  half  an  inch.  Between  its  upper  border 
and  the  cricoid  cartilage  is  a  space  about  one-third  of  an  inch  in 
extent,  where  the  trachea  is  free  ;  this  space,  therefore,  is  the  more 
preferable  situation  for  tracheotomy.  But  the  vertical  measure- 
ment of  this  isthmus  is  sometimes  of  very  considerable  length, 
so  that  it  has  been  seen  covering  the  trachea  almost  down  to  the 
sternum.2 

The  thyroid  body  is  closely  connected,  by  areolar  tissue,  to  the 
sides  of  the  trachea,  to  the  cricoid  and  thyroid  cartilages.  Hence 
it  rises  and  falls  with  the  larynx  in  deglutition. 

The  thyroid  varies  in  size  in  different  individuals  and  at  dif- 
ferent periods  of  life.  It  is  relatively  larger  in  the  child  than  the 
adult,  in  the  female  than  the  male.  In  old  age  it  diminishes  in 
size,  becomes  firmer,  and  occasionally  contains  earthy  matter.3 

By  far  the  most  notable  considerations  in  respect  to  the  thyroid 

1  Concerning  the  development  of  the  lateral  halves  and  central  portion  of  the 
thyroid  body,  see  a  paper  by  Callender  in  the  Proceedings  of  tJie  Royal  Society,  1867. 

2  From  the  upper  part  of  the  isthmus,  or  from  the  adjacent  border  of  either 
lobe,  most  commonly  the  left,  a  conical  prolongation  of  the  thyroid  body,  called 
the  pyramid,  frequently  ascends  in  front  of  the  crico-thyroid  membrane,  as  high 
as  the  pomum  Adami,  and  is  attached  to  the  body  of  the  os  hyoides  by  fibrous 
tissue.     In  some  subjects  we  may  observe  a  few  muscular  fibres  passing  from  the 
os  hyoides  to  the  pyramid.     This  constitutes  the  levator  glandules  thyroidece  (see 
preparation  in  Museum  of  St.  Earth.  Hosp.,  Patholog.  Series,  No.  14)  of  some 
anatomists.     There  are  instances  in  which  the  pyramid  is  double  ;  and,  lastly,  we 
have  seen  a  considerable  portion  of  this  thyroid  substance  lying  over  the  crico- 
thyroid   membrane,    completely    isolated    from    the   rest   of  the   organ.     These 
varieties  deserve  notice,  because  any  one  portion  of  this  structure  may  become 
enlarged  independently  of  the  rest,  and  occasion  a  bronchocele. 

3  The  thyroid  body  is,  primarily,  developed  as  a  pouch  from  the  anterior  wall 
of  the  pharynx ;  the  lateral  lobes  are  first  formed,  and  are  subsequently  united  by 
the  isthmus.    W.  Muller,  Jenaisch.  Zeitsch.  1871. 


THYROID    BODY.  87 

body  are  the  number,  the  large  size,  and  the  free  inosculations  of 
its  arteries.  The  superior  thyroid  arteries  come  from  the  external 
carotid  and  enter  the  front  surface  of  the  apex  of  each  lobe  ;  the 
inferior  thyroid  come  from  the  subclavian,  and  enter  the  under  sur- 
face of  the  base.  An  artery,  called  the  middle  thyroid  (thyroidea 
ima),  is  observed  in  some  subjects ;  it  is  given  off  from  the  arteria 
innominata,  or  the  arch  of  the  aorta,  and  ascends  directly  in  front 
of  the  trachea  to  the  isthmus. 

Its  veins  are  equally  large,  and  form  a  plexus  upon  it.  The 
superior  and  middle  thyroid  veins  cross  the  common  carotid,  and 
open  into  the  internal  jugular.  The  inferior  thyroid  veins,  two  in 
number,  descend  over  the  front  of  the  trachea,  communicate  freely 
with  each  other,  and  terminate  in  the  left  brachio-cephalic  vein. 
When  you  perform  tracheotomy,  bear  in  mind  the  size  of  these 
inferior  thyroid  veins,  and  the  possible  existence  of  a  middle  thyroid 
artery. 

Its  nerves  are  furnished  by  the  middle  and  inferior  cervical 
ganglia  of  the  sympathetic.  They  accompany  the  arteries. 

The  lymphatics  of  the  thyroid  body  are  both  numerous  and 
large.  They  form  a  dense  network  on  the  surface,  and  pass  into 
the  connective  tissue  of  the  gland,  and  eventually  '  enclose  the 
primary  lobes  in  complete  rings  or  more  or  less  perfect  arches.' 
On  the  right  side  they  open  into  the  right  lymphatic  duct,  on  the 
left  side  into  the  thoracic  duct. 

STRUCTURE  OF  The  thyroid  body  belongs  to  the  class  of  duct- 

THE  THYROID  less  glands,  since  no  excretory  duct  has  been  dis- 

BoDV-  covered.      It  is  invested  by  a  thin    covering  of 

dense  areolar  tissue,  which  connects  it  with  the  surrounding  struc- 
tures and  also  penetrates  it,  imperfectly  dividing  it  into  lobes  and 
supporting  the  vessels  as  they  enter  it.  It  consists  of  a  multitude 
of  closed  vesicles,  which  are  imbedded  in  a  delicate  reticulum. 
The  cells  vary  in  size,  from  -^-"o  inch  to  that  of  a  pin's  head,  and 
do  not  communicate  with  each  other.  In  hypertrophy  of  the  gland 
we  sometimes  see  them  as  large  as  a  horse-bean,  or  even  larger. 
The  vesicles  are  oval  and  are  lined  by  a  single  layer  of  endothelial 
columnar  cells  containing  a  glairy  yellow  fluid,  in  which  are  found 
a  large  number  of  nuclei,  nucleated  cells,  and  not  infrequently 


88  DEEP    CERVICAL   GLANDS. 

red  blood-cells  in  various  stages  of  disintegration  and  decolorisa- 
tion.1  The  blood-vessels  pass  into  the  connective  tissue  surround- 
ing the  vesicles,  and  form  a  dense  capillary  plexus,  which  comes 
into  close  relation  with  the  vesicular  epithelium  cells,  and  with  the 
endothelium  of  the  lymph-spaces  ;  from  these  lymph-spaces,  which 
are  placed  between  the  vesicles,  the  lymphatics  have  their  com- 
mencement. The  function  of  the  gland  is  probably  that  of  disin- 
tegration of  the  red  blood-cells,  and  of  the  conveyance  into  the 
general  lymphatic  system  of  the  products  of  these  degenerative 
changes. 

An  enlargement  of  the  thyroid  body  is  termed  a  '  bronchocele.' 
If  the  relation  of  its  lobes  to  the  trachea  and  oesophagus  be  pro- 
perly understood,  it  is  easy  to  predicate  the  consequences  which 
may  result  from  their  enlargement.  The  nature  and  severity  of 
the  symptoms  will  to  a  certain  extent  be  determined  by  the  part 
of  the  organ  affected.  An  enlargement  of  the  left  lobe  is  more 
likely  to  produce  a  difficulty  in  swallowing,  on  account  of  the  in- 
clination of  the  oesophagus  towards  the  left  side.  If  the  isthmus 
be  enlarged,  difficulty  in  breathing  will  probably  be  the  prominent 
symptom,  and,  in  order  to  remove  this  danger,  the  isthmus  has  been 
divided,  and  in  part  removed. 

An  instance  is  related  by  Allan  Burns  in  which  the  isthmus 
was  placed  between  the  trachea  and  the  oesophagus.  It  must  be 
obvious  that  enlargement  of  a  part  so  situated  would  occasion 
great  difficulty  in  swallowing.  I  have  seen  two  cases  in  which 
the  lateral  lobes  projected  so  far  inwards  that  they  completely 
embraced  the  back  of  the  oesophagus. 

Small  lymphatic  glands  are  observed  about  the  thyroid  body, 
especially  in  front  of  the  trachea ;  one  is  often  situated  over  the 
crico-thyroid  membrane.  These  glands,  if  enlarged  by  disease, 
might  be  mistaken  for  a  small  bronchocele. 

DEEP  CERVICAL          In  the  connective  tissue  which  surrounds  the 
LYMPHATIC  great  vessels  of  the  neck,  we  meet  with  a  series 

GLANDS.  of  lympnatic   glands,    called   the    deep    cervical. 

They  form  an  uninterrupted  chain  (whence  their  name  glandulce 

1  Baber,  '  Eesearches  on  the  Minute  Structure  of  the  Thyroid  Gland,'  Philos. 
Trans.  1881. 


DEEP   CERVICAL   GLANDS.  89 

concatenates),  from  the  baSe  of  tlie  skull,  along  the  side  of  the 
neck,  to  the  clavicle,  beneath  which  they  are  continuous  with  the 
thoracic  and  the  axillary  glands.  Some  of  these  glands  lie  anterior 
to  the  common  carotid  artery ;  others,  between  it  and  the  spine. 
This  disposition  explains  the  well-known  fact,  that,  when  these 
glands  are  enlarged,  the  great  vessels  and  nerves  of  the  neck  are 
liable  to  become  imbedded  in  their  substance. 

The  glands  are  particularly  numerous  near  the  division  of  the 
common  carotid,  by  the  side  of  the  pharynx,  and  the  posterior 
belly  of  the  digastricus.  The  lymphatics  connected  with  them 
come  from  all  parts  of  the  head  and  neck.  These  vessels  unite, 
to  form,  on  both  sides  of  the  neck,  one  or  more  absorbent  trunks, 
called  the  jugular.  On  the  left  side  this  jugular  trunk  joins  the 
thoracic  duct,  or  opens  by  a  separate  orifice  into  the  junction  of 
the  left  internal  jugular  and  subclavian  veins :  on  the  right  side  it 
opens  into  the  right  lymphatic  duct,  a  short  trunk  about  half  an 
inch  in  length,  which  terminates  at  the  angle  of  the  junction  of  the 
right  internal  jugular  and  subclavian  veins.  The  terminations  of 
the  thoracic  duct  and  the  right  lymphatic  duct  are  guarded  by  two 
small  semilunar  valves,  in  order  to  prevent  regurgitation  of  blood 
back  from  the  veins. 

The  contiguity  of  the  glands  to  the  great  vessels  and  nerves  of 
the  neck  explains  the  symptoms  produced  by  their  enlargement. 
The  tumour  may  be  so  situated  as  to  be  raised  and  depressed  by 
the  pulsation  of  the  carotid,  and  thus  simulate  an  aneurism.  A 
careful  examination,  however,  will  distinguish  between  an  inher- 
ent and  a  communicated  pulsation.  By  grasping  the  tumour  we 
become  sensible  that  the  pulsation  does  not  depend  upon  any 
variation  of  its  magnitude,  but  upon  the  impulse  derived  from  the 
artery ;  consequently,  if  the  tumour  be  lifted  from  the  vessel,  all 
feeling  of  pulsation  ceases. 

SURVEY  OF  THE  The  parts  in  the  central  line  of  the  neck  should 
CENTKAL  LINE  OF  now  be  well  studied  (fig.  26,  p.  78).  Beginning 
THE  NECK.  a£  f-^e  chj^  we  observe  the  insertions  of  the  di- 

gastric muscles.  Below  these  is  the  junction,  or  raphe,  of  the 
mylo-hyoid  muscles.  Then  comes  the  os  hyoides.  Below  the 
os  hyoides  is  the  thyro-hyoid  membrane,  attached  above  to  the 


90  CENTRAL   LINE   OF   THE   NECK. 

posterior  and  upper  border  of  the  hyoid  bone,  and  below  to  the 
thyroid  cartilage.  Next  is  the  pomum  Adami,  or  projection  of  the 
thyroid  cartilage,  which  is  apparent  between  the  contiguous  borders 
of  the  sterno-hyoidei.  Below  the  thyroid  cartilage  is  the  cricoid. 
These  two  cartilages  are  connected  by  the  crico-thyroid  membrane, 
across  which  runs  the  crico-thyroid  artery  to  join  its  fellow.  Below 
the  cricoid  cartilage  is  the  trachea.  This  is  crossed  by  the  isthmus 
of  the  thyroid  body,  and  lower  down  it  recedes  from  the  surface, 
covered  by  the  inferior  thyroid  veins. 

Now  the  chief  surgical  interest  lies  just  above,  and  just  below, 
the  cricoid  cartilage.  This  cartilage  can  be  felt  very  plainly  in 
the  living  subject  at  any  age,  no  matter  how  fat.  In  laryngotomy, 
the  crico-thyroid  membrane  is  divided  transversely.  The  mem- 
brane should  be  divided  close  to  the  edge  of  the  cricoid  c.,  for  two 
reasons  :  1.  In  order  to  be  farther  from  the  vocal  cords.  2.  To 
avoid  the  crico-thyroid  artery  which  crosses  the  middle  of  the 
membrane.  If  more  room  be  required,  the  cricoid  cartilage  should 
be  divided  longitudinally. 

In  tracheotomy,  the  trachea  may  be  opened  by  a  perpendicular 
incision,  above  the  isthmus  of  the  thyroid  body,  or  below  it.  The 
operation  above  the  isthmus,  if  there  be  space  enough  for  the  in- 
troduction of  the  tube,  is  the  easier  and  safer  of  the  two  ;  for  here 
the  trachea  is  nearer  to  the  surface,  and  no  large  blood-vessels  are, 
generally  speaking,  in  the  way.  The  space  available  measures 
from  a  quarter  to  half  an  inch  ;  and  the  isthmus  is  not  so  firmly 
adherent  to  the  trachea  as  to  prevent  its  being  drawn  downwards 
for  a  short  distance.  However,  it  is  right  to  state  that,  in  one 
case  out  of  every  eight  or  ten,  there  is  no  available  space. 

Tracheotomy  below  the  isthmus  is  neither  an  easy  nor  a  safe 
operation,  for  many  reasons :  1 .  The  trachea  recedes  from  the 
surface  as  it  descends,  so  that  just  above  the  sternum  it  is  nearly 
an  inch  and  a  half  from  the  skin.  2.  The  large  inferior  thyroid 
veins  are  in  the  way.  3.  A  middle  thyroid  artery  may  run  up  in 
front  of  the  trachea,  direct  from  the  arteria  innominata.  4.  The 
arteria  innominata  itself  lies  sometimes  upon  the  trachea  higher 
than  usual,  and  ma,y,  therefore,  be  in  danger.  5.  The  left  brachio- 
cephalic  vein  in  some  cases  crosses  the  trachea  above  the  edge  of 


DIGASTRIC   TRIANGLE.  91 

the  sternum  instead  of  below  it.  The  celebrated  French  surgeon 
Beclard  used  to  relate  in  his  lectures  the  following  occurrence : 
A  student  had  fallen  into  the  Seine,  and  was  nearly  drowned.  As 
he  was  recovering  very  gradually,  some  kind  friends  attempted  to 
accelerate  the  process  by  making  an  opening  into  the  trachea.  In 
so  doing  they  wounded  the  brachio-cephalic  vein.  Blood  poured 
into  the  trachea,  and  the  result  was  instantly  fatal. 

Whoever  pays  attention  to  this  subject  in  the  dissecting-room 
will  soon  be  convinced  of  the  fact  that,  not  only  large  veins,  but 
large  arteries,  occasionally  cross  the  crico-thyroid  membrane  as  well 
as  the  trachea,  thus  showing  the  necessity  of  cutting  cautiously . 
down  to,  and  fairly  exposing,  the  air  tube  before  we  venture  to 
open  it.  It  is  preferable,  after  making  the  first  incision  through 
the  skin,  to  lay  aside  the  sharp  knife  and  to  use  a  blunt  one,  so 
that  the  tissues  may  be  torn  rather  than  cut ;  by  this  proceeding 
the  liability  to  haemorrhage  is  materially  lessened. 

When  the  platysma  and  the  cervical  fascia  have 
DISSECTION  OF  . 

THE  SUBMAXILLAEY    keen  removed  from  their  attachment  to  the  jaw, 

EEGION  OB  THE         the  most  conspicuous  object  is  the  submaxillary 
gland.    Observe  that  the  fascia  is  here  very  strong, 
and  forms  for  the  gland  a  complete  capsule.     Be- 
neath the  jaw  are  several  lymphatic  glands,  from  six  to  ten  in 
number,  of  which  some  lie  superficial  to  the  salivary  gland,  others 
beneath  it.     These  glands  receive  the  lymphatics  of  the  face,  the 
tonsils  and  the  tongue. 

A  little  dissection  will  expose  a  muscle  called  the  digastricus, 
consisting  of  two  distinct  fleshy  portions  connected  by  a  tendon. 
They  form,  with  the  body  of  the  jaw,  a  triangle  called  the  digastric, 
of  which  we  propose  to  examine  the  contents.  The  muscles  form- 
ing its  floor  are  the  mylo-hyoideus  and  hyo-glossus.  Under  the 
submaxillary  gland  is  the  facial  artery,  which  here  runs  a  tortuous 
course,  and  finally  turns  up  over  the  lower  jaw  in  front  of  the 
masseter  muscle.  Lying  on  the  mylo-hyoideus,  under  cover  of  the 
lower  jaw,  is  the  submental  artery,  accompanied  by  the  mylo-hyoid 
nerve  and  artery.  Behind  the  submaxillary  gland,  and  separating 
it  from  the  parotid,  which  also  is  contained  within  this  triangle,  is 
the  stylo-maxillary  ligament.  Ascending  and  then  entering  the 


92 


DIGASTRICUS. 


parotid  is  the  external  carotid  artery,  in  front  of  which  is  the 
infra-maxillary  branch  of  the  facial  nerve.  Deep  in  this  space  are 
situated  the  internal  jugular  vein,  the  internal  carotid  artery,  and 
the  pneumogastric  nerve;  and  running  obliquely  forwards  between 
the  internal  and  external  carotid  arteries  are  the  stylo-glossus, 

FIG.  27. 


Facial  a. 
Mylo-hyoid  n. 


Submcntal  a. 


Occipital  a.     .    .    . 


Hypoglossal  n 

Descendens  noni  n. 
Lingual  a 

Internal  jugular  v. 
Superior  thyroid  a.     . 


Common  carotid  a. 


DIGASTRIC    TRIANGLE    AND    CONTENTS. 


DlGASTRICUS. 


stylo-pharyngeus,   glosso-pharyngeal    nerve,   and   the    stylo-hyoid 
ligament. 

The  dif/astricm  consists  of  two  muscular  bellies 
united  by  an  intermediate  tendon.  The  posterior 
belly  arises  from  the  digastric  fossa  of  the  temporal  bone,  passes 
obliquely  downwards^  forwards,  and  inwards,  and  then  ascends  to 
be  inserted  by  its  anterior  belly  close  to  the  symphysis  of  the  lower 


DIGASTRIC    TRIANGLE.  93 

jaw.  Raise  the  submaxillary  gland  to  see  the  intermediate  tendon 
of  the  digastricus  piercing  the  stylo-hyoid  muscle,  the  angle  which 
it  forms,  and  how  it  is  fastened  by  aponeurosis  to  the  body  and 
the  greater  cornu  of  the  os  hyoides.  Observe  also  that  this 
aponeurosis — supra-liyoid  aponeurosis — is  connected  in  the  mesial 
line  with  its  fellow  of  the  opposite  side,  so  that  a  fibrous  expan- 
sion occupies  the  interval  between  the  anterior  portions  of  the 
digastrici. 

The  chief  action  of  the  digastricus  is  to  depress  the  lower  jaw. 
But  if  the  lower  jaw  be  fixed,  then  the  muscle  raises  the  os  hyoides, 
as  in  deglutition. 

The  posterior  belly  of  the  digastricus  is  supplied  by  a  nerve 
from  the  facial;  the  anterior  belly  by  a  branch  from  the  mylo- 
hyoidean  nerve  (which  comes  from  the  third  division  of  the  fifth 
pair). 

STYLO-  The  stylo-hyoideus  arises  from  the   middle  of 

HYOIDEUS.  the  styloid  process  of  the  temporal  bone,  and  pass- 

ing downwards  and  forwards  is  inserted  into  the  body  of  the  os 
hyoides.  This  muscle  at  first  runs  above  the  posterior  belly  of  the 
digastricus,  and  near  its  insertion  is  pierced  by  the  digastric 
tendon.  Its  nerve  is  derived  from  the  facial  close  to  its  exit  from 
the  stylo-mastoid  foramen,  in  common  with  the  branch  to  the  pos- 
terior belly  of  the  digastricus.1  Its  action  is  to  raise  and  draw 
back  the  os  hyoides. 

The  digastric  triangle  is  bounded  above  by  the  horizontal  ramus 
of  the  lower  jaw,  and  mastoid  process  of  the  temporal  bone ;  behind 
by  the  posterior  belly  of  the  digastricus  ;  and  in  front  by  the  ante- 
rior belly.  The  objects  to  be  examined  in  this  triangle  are  twelve 
in  number,  as  follow — 

1.  Submaxillary  salivary  gland.  7.  Stylo-maxillary  ligament. 

2.  Facial  vein.  8.  Part  of  the  parotid  gland. 

3.  Facial  artery.  9.  Part  of  the  external  carotid  artery. 

4.  Submental  artery.  10.  Mylo-hyoideus  muscle. 

5.  Mylo-hyoidean  nerve.  11.  Hypcglossal  nerve. 

6.  Submaxillary  lymphatic  glands.  12.  Part  of  the  hyo-glossus  muscle. 


1  In  many,  if  not  in  most  subjects,  a  small  filament  from  the  hypoglossal  nerve 
is  distributed  to  this  muscle. 


94  FACIAL   VEIN. 

SUBMAXILLARY  In  the  ordinary  position  of  the  head,  the  sub- 

SALIVARY  GLAND.  maxillary  gland  is  partially  concealed  by  the  jaw, 
but  when  the  head  falls  back  the  gland  is  more  exposed.  It  is 
about  the  size  of  a  chestnut,  weighs  about  two  drachms,  and  is 
divided  into  several  lobes.  Its  upper  margin  is  covered  by  the 
body  of  the  jaw ;  its  lower  margin  overlaps  the  side  of  the  os 
hyoides.  Its  cutaneous  surface  is  flat,  being  covered  only  by  the 
skin,  platysma,  and  deep  cervical  fascia  ;  but  the  lobes  on  its  deep 
surface  are  irregular,  and  often  continuous  with  those  of  the  sub- 
lingual  gland.  By  raising  the  gland  we  find  that  it  lies  upon  the 
mylo-hyoideus,  the  hyo-glossus,  the  stylo-glossus,  the  tendon  of 
the  digastricus,  and  a  portion  of  the  hypoglossal  nerve,  seen  above 
the  tendon.  Part  of  the  gland  passes  beneath  the  posterior  border 
of  the  mylo-hyoid,  and  not  infrequently  becomes  continuous  with 
the  sublingual  gland.  The  facial  artery  lies  in  a  groove  on  its 
deeper  surface,  and  subsequently  upon  its  upper  border ;  and  it  is 
separated  from  the  parotid  gland,  which  is  situated  behind  it,  by 
the  stylo-maxillary  ligament.  Mark  these  relations  well,  because 
they  are  of  importance,  as  will  be  presently  explained  in  tying  the 
lingual  artery. 

The  duct  of  the  gland  cannot  at  this  stage  of  the  dissection 
be  traced  further,  for  it  runs  forwards,  under  cover  of  the  mylo- 
hyoideus,  to  end  in  the  floor  of  the  mouth,  by  the  side  of  the 
frgenum  linguae.  The  description  of  its  course  and  relations  had 
better  therefore  be  deferred  till  it  can  be  dissected  in  its  whole 
length  with  the  gustatory  nerve  in  the  pterygoid  region. 

_,         „  The  facial  vein  does  not  accompany  the  facial 

artery,  but  runs  nearly  a  straight  course.  It 
leaves  the  face  at  the  anterior  edge  of  the  masseter  m.,  then  runs 
over  the  submaxillary  gland,  the  digastricus  and  stylo-hyoideus  and 
the  carotid  artery,  to  join  the  internal  jugular.  This  is  the  rule 
— but  there  are  frequent  exceptions.  Before  it  empties  itself  into 
the  internal  jugular  it  is  joined  by  a  large  branch  from  the  external 
jugular  vein.  The  principal  point  to  remember  is,  that  the  vein 
runs  superficial  to  the  gland,  and  that  we  must  be  cautious  in 
opening  abscesses  under  the  jaw. 


EXTERNAL  CAROTID  ARTERY.  95 


COURSE  AND  course  and  relations  of  the  external  carotid 

EELATIONS  OF  THE  artery,  and  its  branches  in  the  neck,  should  now 
EXTERNAL  CAROTID  be  made  out  as  far  as  the  parotid  gland.  In  pre- 
ARTERY.  paring  a  view  of  them,  observe  that  nearly  all  the 

veins  lie  in  front  of  their  corresponding  arteries.  In  removing 
the  connective  tissue,  fat  and  lymphatic  glands,  the  student  must 
take  care  of  the  nerves  and  other  structures  which  are  liable  to  be 
injured. 

The  external  carotid  arises  from  the  common  carotid  about  the 
level  of  the  upper  border  of  the  thyroid  cartilage.  It  ascends  to  the 
interval  between  the  ear  and  the  jaw  in  a  slightly  curved  direction, 
at  first  forwards  and  then  backwards.  The  external  and  the  internal 
carotids  are  in  the  adult  nearly  of  equal  size  ;  but  the  external  rapidly 
diminishes  in  size,  owing  to  the  large  branches  it  gives  off  within 
a  short  distance.  At  first  it  lies  beneath  the  skin,  superficial  fascia, 
platysma  myoides,  deep  cervical  fascia,  some  of  the  superficial  cer- 
vical nerves,  and  the  sterno-mastoid  muscle.  It  is  next  crossed 
by  the  hypoglossal  nerve,  the  facial  and  lingual  veins,  the  posterior 
belly  of  the  digastricus  and  stylo-hyoideus  ;  it  then  enters  the 
parotid  gland,  where  it  lies  beneath  the  facial  nerve  and  the 
external  jugular  vein,  and  terminates  between  the  external  audi- 
tory meatus  and  the  neck  of  the  jaw,  by  dividing  into  the  temporal 
and  internal  maxillary  arteries.  Internally  the  artery  is  in  relation 
with  the  hyoid  bone,  the  pharynx,  the  parotid  gland,  and  the 
posterior  border  of  the  ascending  ramus  of  the  lower  jaw. 

Behind  the  external  carotid,  and  separating  it  from  the  in- 
ternal, are  the  stylo-glossus,  the  stylo-pharyngeus,  the  glosso- 
pharyngeal  nerve,  and  the  stylo-hyoid  ligament.  The  superior 
laryngeal  nerve  and  part  of  the  parotid  gland  are  also  placed 
behind  the  artery. 

Notice  the  relative  position  which  the  external  and  internal 
carotids  bear  to  each  other.  The  external  lies  at  first  on  the 
same  plane  with,  but  nearer  to  the  side  of  the  pharynx  than 
the  internal.  It  soon,  however,  changes  its  position,  and  crosses 
obliquely  in  front  of  the  internal  to  reach  the  space  between  the 
angle  of  the  jaw  and  the  mastoid  process.  The  internal  carotid 


<)G  SUPERIOR    THYROID    ARTERY. 

ascends  perpendicularly  by  the  side  of  the  pharynx  to  the  base  of 
the  skull. 

The  external  carotid  gives  off  the  following  branches — 

1.  The  superior  thyroid.  5.  The  posterior  auricular. 

2.  The  lingual.  6.  The  internal  maxillary. 

3.  The  facial.  7.  The  temporal. 

4.  The  occipital.  8.  The  ascending  pharyngeal. 

SUPERIOR  The  superior  thyroid,  the  first  branch  of  the 

THYKOID  AKTEKY.  external  carotid,  arises  just  below  the  great  cornu 
of  the  os  hyoides.  It  lies  in  the  superior  carotid  triangle,  and, 
curving  downwards  and  inwards,  runs  beneath  the  omo-hyoid, 
sterno-hyoid,  and  sterno-thyroid  muscles  to  the  upper  and  front 
surface  of  the  thyroid  body,  in  which  it  terminates.  Its  branches 
are  the  four  following : — 

1.  The  hyoid,  a  small  muscular  branch,  runs  horizontally  inwards 
below  the  greater  cornu  of  the  os  hyoides,  and  anastomoses  with  its 
fellow. 

2.  The   siqjerior   laryngeal   branch,    accompanied  by  the  superior 
laryngeal  nerve,  runs  inwards  beneath  the  thyro-hyoid  muscle,  pierces 
the  thyro-hyoid  membrane  (sometimes  the  thyroid  cartilage),  supplies 
the  muscles  and  the  mucous  membrane  of  the  larynx,  and  anastomoses 
with  its  fellow  of  the  opposite  side. 

3.  The  middle  sterno-mastoid,  a  small  branch,  variable  as  to  origin, 
descends  over  the  sheath  of  the  common  carotid  artery,  and  enters  the 
under  aspect  of  the  sterno-mastoid  muscle. 

4.  The  crico-thyroid,  an  artery  of  great  interest  in  reference  to  the 
operation  of  laryngotomy,  crosses  the  crico-thyroid  membrane,  and  com- 
municates with  a  corresponding  branch  on  the  opposite  side  (fig.  26, 
p.  78).     One  or  two  small  branches  pass  through  the  membrane  to  the 
interior  of  the  larynx.     It  is  important  to  know  that  the  crico-thyroid 
artery  often  varies  in  direction  and  size.     In  most  cases  it  is  small,  and 
runs  across  the  centre  of  the  membrane  ;  we  should  therefore  be  least 
likely  to  wound  it  in  laryngotomy,  by  dividing  the  membrane  close  to 
the  cricoid  cartilage.     But  it  is  by  no  means  infrequent  to  find  this 
artery  of  considerable  size,  taking  an  oblique  or  even  a  perpendicular 
direction  in  front  of  the  membrane,  and  finally  distributed  to  one  of 
the  lobes  of  the  thyroid  body.    We  have  seen  several  instances  in  which 
the  membrane  was  crossed  by  .the  main  trunk  of  the  superior  thyroid. 


BRANCHES  OF  THE  EXTERNAL,  CAROTID. 


These  facts  should  establish  the  practical  rule  in  laryngotomy,  not  to 
make  an  opening  into  the  larynx  until  it  has  been  fairly  exposed. 


FIG.  28. 


POST.  ANT. 

/  TEMPORAL! 


ASAL 


SUP. 

CORONARY 


A.FR/ENUM 


CRICO-THYR01D 


MIDDLE  STERNC-MASTOID 


DIAGRAM   OF    THE    BRANCHES    OF    THE    EXTERNAL  CAROTID  ARTERY    AND 
THEIR   BRANCHES. 

Among  the  many  arterial  inosculations  about  the  thyroid  body 
are  two  which  deserve  notice  :  the  one  is  formed  between  the  two 
superior  thyroid  arteries  along  the  upper  border  of  the  isthmus ; 

H 


98  FACIAL   ARTERY. 

the  other  takes  place  along  the  back  part  of  the  lateral  lobe  between 
the  superior  and  inferior  thyroid  arteries  of  the  same  side. 

The  superior  thyroid  vein  leaves  the  upper  part  of  the  thyroid 
body,  crosses  over  the  common  carotid  artery,  and  joins  the  internal 
jugular  or  the  facial  vein. 

SUPERIOR  LARYK-       The  superior  laryngeal  nerve,  mentioned  as  ac- 
GEAL  NERVE.  companying  the  superior  laryngeal  artery,  is  given 

off  from  the  inferior  ganglion  of  the  pneumogastric  nerve.  It 
descends  by  the  side  of  the  pharynx,  behind  both  carotid  arteries, 
and  divides  into  two  branches — the  internal  and  external  laryngeal 
nerves.  The  internal  branch  enters  the  larynx  through  the  thyro- 
hyoid  membrane  accompanied  by  the  superior  laryngeal  artery,  and 
supplies  the  mucous  membrane  of  the  larynx  with  its  exquisite 
sensibility.  Some  of  its  branches  may  be  traced  upwards  in  the 
ary-epiglottidean  fold  to  supply  the  epiglottis  and  the  base  of  the 
tongue ;  others  descend  to  the  rima  glottidis ;  a  large  branch  passes 
down  behind  the  ala  of  the  thyroid  cartilage  to  join  the  recurrent 
laryngeal  nerve ;  and  a  small  branch  pierces  the  arytenoideus  to 
supply  the  mucous  membrane  beneath  it.  The  external  branch, 
descending  beneath  the  depressors  of  the  larynx,  accompanies  the 
crico-thyroid  artery,  and  after  distributing  filaments  to  the  pharyn- 
geal  plexus,  supplies  the  thyroid  body,  the  inferior  constrictor,  and 
the  crico-thyroid  muscles.  It  receives  a  branch  from  the  superior 
cervical  ganglion  of  the  sympathetic,  and  sends  off  a  cardiac  fila- 
ment to  join  the  superior  cardiac  branch  of  the  sympathetic  behind 
the  common  carotid  artery. 

LINGUAL  The  lingual  artery  and  its  branches  will  be  de- 

ARTEBY.  scribed  in  the  dissection  of  the  submaxillary  region. 

The  facial  artery  is  the  third  branch  of  the 

external  carotid.     It  runs  tortuously  under  the 

hypoglossal  nerve,  the  posterior  belly  of  the  digastricus  and  stylo- 

hyoideus,  and  beneath  or  through  the  substance  of  the  submaxillary 

gland  to  the  face,  where  it  appears  at  the  anterior  border  of  the 

masseter.     Below  the  jaw  the  facial  rests  on  the  mylo-hyoideus, 

and  gives  off  the  four  following  branches : — 

1.  The  ascending  or  inferior  palatine  artery  runs  up  between  the 
stylo-glossus  and  the  stylo-pharyngeus  m.,  and  behind  the  internal 


MYLO-HYOIDEUS.  99 

pterygoid  m.  to  the  pharynx,  to  which  and  the  neighbouring  parts  it 
gives  branches.  Ascending  as  far  as  the  levator  palati,  it  divides  into 
two  branches  :  one  courses  along  the  tensor  palati  to  supply  the  soft 
palate  ;  the  other  enters  the  tonsil,  and  anastomoses  with  the  descending 
palatine  of  the  internal  maxillary,  and  with  the  tonsillar  branches  of  the 
ascending  pharyngeal. 

2.  The  tonsillar  runs  up  between  the  internal  pterygoid  and  the 
stylo-glossus  m.  ;  then,  perforating  the  superior  constrictor,  it  supplies 
the  tonsil  and  root  of  the  tongue. 

3.  Glandular  branches  to  the  submaxillary  gland  and  side  of  tongue. 

4.  The  submental  arises  from  the  facial  behind  the  submaxillary 
gland,  and  runs  forwards  upon  the  mylo-hyoideus,  beneath  the  inferior 
maxilla,  distributing  branches  in  its  course  to  the  gland  and  the  adjacent 
muscles.     It  then  curves  over  the  bone  and  divides  into  two  branches  : 
a  superficial  one,  which  supplies  the  skin  and  lip  ;  and  a  deep  one,  which 
runs  between  the  muscles  and  the  bone,  and  inosculates  with  the  mental 
and  inferior  labial  arteries.     Beneath  the  inferior  maxilla  it  usually 
inosculates  with  the  sublingual  artery. 

The  remaining  branches  of  the  external  carotid  artery  will  be 
described  later  on. 

MYLO-HYOIDEAN  Look  for  the  mylo-hyoidean  nerve  near  the  sub- 
NEBVE.  mental  artery.  The  nerve  comes  from  the  inferior 

dental  (before  its  entrance  into  the  dental  foramen),  and  running 
along  a  groove  on  the  inner  side  of  the  inferior  maxilla,  advances 
between  the  bone  and  the  internal  pterygoid  m.,  to  supply  the 
mylo-hyoideus  and  the  anterior  belly  of  the  digastricus. 

SUBMAXILLABY  The  submaxillary  lymphatic  glands  receive  the 

LYMPHATIC  lymphatics  of  the  face  and  the  tongue.  They  are 

GLANDS.  often  enlarged  in  cancerous  diseases  of  the  tongue 

or  the  lower  lip.  It  should  be  remembered  also  that  there  are 
lymphatic  glands  in  the  mesial  line  below  the  chin. 

MYLO-  The  mylo-hyoideus,  a  triangular  muscle,  arises 

HYOIDEUS.  from  the  mylo-hyoid  ridge  of  the  lower  jaw,  from 

the  symphysis,  as  far  back  as  the  last  molar  tooth.  Its  posterior 
fibres  are  inserted  into  the  body  of  the  os  hyoides,  the  anterior 
being  attached  to  a  median  tendinous  line,  termed  the  raplie, 
Thus  the  muscles  of  opposite ,  yiotef-s1  ferfn^ja,  mu'soiijaf  fiber  for  the 
mouth.  Superficially,  it  is  in  relation*  with  the1  anterior  belly  of 


100  STYLO-MAXILLARY    LIGAMENT. 

the  digastricus,  the  submaxillary  gland,  the  submental  artery,  and 
the  mylo-hyoidean  n.  By  its  deep  surface,  it  is  in  relation  with 
part  of  the  hyo-glossus,  the  stylo-glossus,  the  genio-hyoideus, 
Wharton's  duct,  the  gustatory  and  hypoglossal  nerves-  with  their 
communications,  and  the  sublingual  gland.  It  is  supplied  with 
nerves  by  the  mylo-hyoid  branch  of  the  inferior  dental ;  with  blood 
by  the  submental  artery.  The  muscles  of  opposite  sides  conjointly 
elevate  the  os  hyoides  and  the  floor  of  the  mouth — as  in  degluti- 
tion. 

STYLO -MAXIL-  This  is  a  layer  of  the  deep  cervical  fascia,  ex- 

IABY  LIGAMENT.  tending  from  the  angle  of  the  jaw  to  the  styloid 
process.  It  is  a  broad  sheet  of  fascia,  and  separates  the  submax- 
illary gland  from  the  parotid.  It  is  continuous  with  the  fascia 
covering  the  pharynx ;  this  gives  it  a  surgical  interest,  because 
it  prevents  accumulations  of  matter  formed  near  the  tonsils  and 
upper  part  of  the  pharynx  from  coming  to  the  surface. 

The  remaining  objects  seen  in  the  submaxillary  triangle — 
namely,  the  parotid  gland,  the  hypoglossal  nerve,  the  hyo-glossus 
muscle — will  be  described  presently  when  they  can  be  better  seen. 
Your  attention  should  now  be  directed  to  a  piece  of  surgical  ana- 
tomy, which  will  enable  you  readily  to  find  and  tie  the  lingual 
artery.  It  is  this  : — 

A  curved  incision,  about  two  inches  in  length,  being  made  from 
the  lesser  cornu  along  the  upper  border  of  the  great  cornu  of  the 
os  hyoides,  through  the  skin,  the  platysma,  and  the  cervical  fascia, 
you  will  come  upon  the  lower  edge  of  the  submaxillary  gland. 
Lift  up  the  gland,  which  is  easily  done,  and  underneath  it  you 
will  observe  that  the  tendon  of  the  digastricus  makes  two  sides 
of  a  triangle,  of  which  the  base  is  formed  by  the  hypoglossal  nerve 
crossing  the  hyo-glossus  muscle.  Within  this  little  triangle,  cut 
transversely  through  the  fibres  of  the  hyo-glossus  :  under  them  is 
the  lingual  artery,  lying  on  the  middle  constrictor.  The  first  time 
you  perform  this  operation  on  the  dead  subject,  you  will  not  un- 
likely miss  the  artery  and  cut  through  the  middle  constrictor  into 
the  pharynx. 

j  /•.  **The!3fa*cial  Wsels.'niuSt  now  be  divided  imme- 

*•    t  •  •  %     *  c  *      *         ••      •  ^»  •  •  •      • 

1  '     diately  ibelow  the  *jaW.  *  'Reflect  the  anterior  belly 
of  thfe /dvga^tiou^  vfi*(5,m  ils/insetijigii|;"43tach  the  mylo-hyoideus 


HYO-GLOSSUS.  101 

from  the  middle  line  and  the  os  hyoides,  and  turn  it  over  the  body 
of  the  jaw,  taking  care  not  to  injure  the  muscles  and  structures 
beneath.  The  lower  jaw  must  now  be  sawn  through,  a  little  to 
the  dissector's  side  of  the  symphysis,  and  the  bone  drawn  upwards 
by  hooks.  The  tongue  should  then  be  drawn  out  of  the  mouth,  and 
fastened  by  hooks.  The  os  hyoides  should  be  drawn  down  by  means 
of  hooks,  so  as  to  put  the  parts  on  the  stretch.  All  this  done,  we 
have  to  make  out,  by  carefully  cleaning  away  the  fat  and  connective 
tissue,  the  following  objects  represented  in  fig.  29,  p.  102 — 

1.  Genio-hyoideus.  (5.  Sublingual  gland. 

2.  Hyo-glossus.  7.  Hypoglossal  nerve. 

3.  Stylo-glossus.  8.  Gustatory  nerve. 

4.  Genio-hyo-glossus.  9.  Submaxillary  ganglion. 

5.  Submaxillary  duct.  10.  Lingual  artery. 

GENIO-  The    genio-hyoideus   arises    from    the    inferior 

HYOIDEOS.  tubercle  .behind   the  symphysis  of  the  jaw,  and 

passes  downwards  and  backwards  to  be  inserted  into  the  front  of 
the  body  of  the  os  hyoides.  This  round  muscle  is  situated  in  the 
mesial  line,  parallel  to  its  fellow.  Its  nerve  comes  from  the 
hypoglossal,  and  its  blood  from  the  lingual  artery.  Its  action  is 
to  draw  the  os  hyoides  forwards  and  upwards  ;  and  if  the  hyoid 
bone  be  fixed,  it  depresses  the  lower  jaw. 

The    hyo-glossus    arises   from    the    body,    the 

HYO-GLOSSUS.  -,   ,  „    ,  ,       .,  , 

greater  and  lesser  cornua  of  the  os  hyoides,  and 

is  inserted  into  the  posterior  two-thirds  of  the  side  of  the  tongue, 
its  fibres  blending  with  the  stylo-glossus  and  palato-glossus.  It  is 
a  square  and  flat  muscle,  and  its  fibres  ascend  nearly  perpen- 
dicularly from  origin  to  insertion.  The  fibres  arising  from  the 
body  of  the  hyoid  bone,  termed  the  l>asio-ylossus,  are  directed 
backwards  and  upwards  and  overlap  the  fibres  which  have  their 
origin  from  the  greater  cornu  and  are  termed  the  Tcerato-glossus . 
Those  that  arise  from  the  lesser  cornu  are  termed  the  chondro- 
(flossus.  The  nerve  to  the  hyo-glossus  comes  from  the  hypo- 
glossal,  and  its  blood  from  the  lingual.  Its  action  (with  that  of 
its  fellow)  is  to  depress  the  tongue.  Observe  the  objects  which 
lie  upon  the  hyo-glossus  ;  namely,  the  hypoglossal  and  gustatory 
nerves  (which  at  the  anterior  border  form  one  or  more  loops  of 
communication  with  one  another),  the  chorda  tympani  nerve,  the 


102 


GENIO-HYO-GLOSSUS. 


submaxillary  ganglion,  the  submaxillary  gland  and  its  duct,  the 
hyoid  branch  of  lingual  artery,  the  lingual  vein,  the  sublingual 
gland,  the  digastricus,  stylo-hyoid,  stylo-glossus,  and  mylo-hyoid 
muscles.  Beneath  the  hyo-glossus  muscle  lie  the  lingual  artery 
and  vein,  part  of  the  middle  constrictor  of  the  pharynx,  part  of  the 
genio-hyo-glossus,  the  lingualis  and  the  glosso-pharyngeal  nerve. 

GENIO-  The  genio-hyo-glossus  arises  by  a  tendon  from 

HYO-GLOSSUS.  the  upper  tubercle  behind  the  symphysis  of  the 

FIG.  29. 


Styloid  process      .    . 

Glosso-pharyngeal  n. 

Hypoglossal  n. 
Occipital  a.     . 

Snbmaxillary  gan- 
glion       

Duct  of  submaxillary 
gland. 

Middle  constrictor  m, 

Lingual  a.     .... 

Descendens  noni  n.  .    _ 


Chorda  tympani  n. 

\\ Gustatory  n. 


MUSCLES,   VESSELS,   AND   NERVES   OF   THE   TONGUE. 

lower  jaw,  and  is  inserted  as  follows :  the  lower  fibres  into  the 
body  of  the  os  hyoides  ;  the  upper  fibres  into  the  tongue  from  the 
base  to  the  apex.  It  is  the  largest  and  most  important  of  the 
muscles  of  the  tongue.  It  is  fan-shaped,  with  the  apex  attached 
to  the  symphysis  ;  thence  its  fibres  radiate  into  the  entire  length  of 
the  tongue.  Externally,  the  muscle  is  in  relation  with  the  stylo- 
glossus,  lingualis,  and  hyo-glossus,  the  lingual  artery,  the  sub- 


HYPOGLOSSAL   NERVE.  103 

lingual  gland,  Wharton's  duct,  the  hypoglossal  and  gustatory 
nerves ;  inferiorly,  by  its  lower  border  it  is  in  contact  with  the 
genio-hyoid  ;  above,  by  its  anterior  border  with  the  mucous  mem- 
brane of  the  mouth  ;  and  internally,  it  is  in  contact  with  its  fellow 
and  the  fibrous  septum  of  the  tongue.  It  derives  its  nerves  from 
the  hypoglossal,  and  its  blood  from  the  lingual  artery.  Its  action 
is  various.  The  posterior  fibres,  by  raising  the  os  hyoides  and 
drawing  forwards  the  base  of  the  tongue,  protrude  the  tongue  out 
of  the  mouth  ;  the  anterior  draw  the  tongue  back  again.  When 
every  part  of  the  muscle  acts,  it  draws  down  the  whole  tongue, 
and  is  therefore  one  of  the  chief  muscles  concerned  in  suction. 

The  stylo-glossus,  a  long  and  slender  muscle, 
STYLO-GLOSSUS.  .  "  .,   ° 

arises  from  the  outer  side  or  the  styloid  process 

near  its  apex  and  from  the  stylo-maxillary  ligament;  its  fibres 
pass  downwards  and  forwards,  and  then  nearly  horizontal,  and  are 
inserted  along  the  side  of  the  tongue.  It  runs  outside  the  hyo- 
glossus  nearly  to  the  tip  of  the  tongue,  and  blends  with  the  fibres 
of  this  muscle,  as  well  as  with  the  palato-glossus.  Its  nerve  comes 
from  the  hypoglossal.  Its  action  is  to  retract  the  tongue. 

HYPOGLOSSAL  The  hypoglossal,  or  twelfth  cranial  nerve,  is  the 

NERVE.  motor  nerve  of  the   muscles  of  the   tongue.     It 

arises  by  several  filaments,  twelve  to  fifteen,  from  the  front  of  the 
medulla  oblongata  between  the  anterior  pyramid  and  the  olivary 
body.  It  pierces  the. dura  mater  in  two  fasciculi  which  leave  the 
skull  through  the  anterior  condylar  foramen ;  these  subsequently 
blend  to  form  a  single  nerve  trunk.  It  lies  deeply  beneath  the 
internal  jugular  vein  and  internal  carotid  artery,  where  it  is 
intimately  connected  with  the  lower  ganglion  of  the  pneumo- 
gastric  nerve ;  it  then  comes  up  between  the  artery  and  vein,  and, 
immediately  below  the  posterior  belly  of  the  digastricus,  curves 
forwards  over  the  occipital,  the  internal  and  external  carotid  and 
facial,  arteries.  Next  it  crosses  the  hyo-glossus  muscle,  and  pass- 
ing beneath  the  mylo-hyoid,  divides  into  branches  which  supply 
the  following  muscles ;  namely,  the  stylo-glossus,  hyo-glossus, 
genio-hyo-glossus,  lingualis,  and  the  genio-hyoideus. 

As  it  curves  round  the  occipital  artery,  the  hypoglossal  nerve 
sends  the  descendens  noni  to  the  depressors  of  the  os  hyoides  (p.  102). 


104  -    LINGUAL   NERVE. 

It  also  sends  a  nerve  to  the  thyro-hyoideus,  which  proceeds  from  it 
where  it  crosses  over  the  external  carotid,  accompanied  by  the 
hyoid  branch  of  the  lingual  artery.  Near  the  anterior  border  of 
the  hyo-glossus,  it  communicates  by  several  loops  with  the  gusta- 
tory nerve.  (Fig.  29.) 

The  hypoglossal  at  its  origin  is  purely  a  motor  nerve.  But 
after  leaving  the  skull,  it  receives  communications  from  the  first 
two  cervical  nerves.  These  communications  are  important  physio- 
logically for  two  reasons :  1 .  They  account  for  the  hypoglossal 
nerve  containing  sensory  fibres.  2.  They  contribute  the  greater 
part  of  the  filaments  of  the  descendens  noni.  It  is  also  connected 
by  small  branches  with  the  pneumogastric  nerve  and  the  superior 
cervical  ganglion  of  the  sympathetic  at  the  base  of  the  skull. 

SUBLINGOAL  The  suHingual  gland  lies  immediately  beneath 

GiiiND.  the  mucous  membrane  of  the  floor  of  the  mouth. 

Its  shape  is  oblong,  with  the  long  axis  (about  an  inch  and  a  half) 
directed  from  before  backwards,  and  it  weighs  about  a  drachm. 
Its  relations  are  as  follows :  above,  it  is  covered  with  mucous 
membrane  ;  beloiv,  it  rests  upon  the  upper  surface  of  the  naylo- 
hyoid  muscle  ;  internally,  it  is  in  contact  with  the  hyo-glossus, 
genio-hyo-glossus,  stylo-glossus,  the  gustatory  nerve  and  Wharton's 
duct ;  posteriorly,  with  the  submaxillary  gland  ;  and  in  front,  it  rests 
in  a  depression  behind  the  symphysis  of  the  lower  jaw. 

The  ducts  of  the  sublingual  gland  (ducts  of  Kivinus  !)  vary  in 
number  from  eight  to  twenty.  They  terminate  by  minute  openings 
behind  the  orifice  of  the  submaxillary  duct,  along  the  ridge  felt  upon 
the  floor  of  the  mouth.  One  or  more  ducts  terminate  in  the  submax- 
illary duct :  one  of  these  takes  the  name  of  the  duct  of  Bartholin. 

The  duct  of  the  submaxillary  gland  may  now  be  traced  across 
the  hyo-glossus,  and  under  the  gustatory  nerve  to  the  floor  of  the 
mouth. 

LINGUAL  OB  This  nerve  is  a  branch  of  the  inferior  maxillary 

GUSTATOB*  NEEVE.  Or  third  division  of  the  fifth  pair  of  cranial  nerves. 
Emerging  beneath  the  external  pterygoid  muscle,  in  company 
with,  but  in  front  of,  the  inferior  dental  nerve,  it  rests  upon  the 
internal  pterygoid  muscle.  It  descends  between  this  latter  muscle 
1  Aug.  Quirin.  Eivinus,  De  Dyspepsia,  Lips.,  1678. 


LINGUAL    ARTERY.  105 

and  the  ramus  of  the  lower  jaw,  and  curves  forwards  towards  the 
side  of  the  tongue  over  the  superior  constrictor  of  the  pharynx, 
along  the. upper  part  of  the  hyo-glossus,  at  the  anterior  border  of 
which  it  crosses,  superficially,  the  duct  of  the  submaxillary  gland 
(fig.  29).  Having  reached  the  under  part  of  the  tongue,  the  nerve 
divides  into  numerous  branches  which  pierce  the  muscular  struc- 
ture of  the  tongue,  and  then  break  up  into  filaments  which  supply 
the  mucous  membrane  and  the  fungiform  and  filiform  papillae  on 
its  anterior  three-fourths.  Beneath  the  external  pterygoid  it  is 
joined  at  an  acute  angle  by  the  chorda  tympani,  a  branch  of  the 
facial  nerve  ;  in  its  course  it  gives  off  some  communicating  branches 
to  the  hypoglossal  nerve  near  the  anterior  border  of  the  hyo-glossus. 
It  supplies  also  the  mucous  membrane  of  the  mouth,  gums,  and 
the  sublingual  gland,  one  or  more  branches  to  the  submaxillary 
ganglion,  and  at  the  apex  of  the  tongue  the  terminal  branches  of 
this  nerve  and  the  hypoglossal  are  connected. 

SUBMAXILLARY  At  the  lower  border  of  the  gustatory  nerve  as 

GANGLION.  it  lies  upon  the  hyo-glossus  muscle,  and  before 

it  crosses  the  submaxillary  duct,  you  will  find  a  small,  convex,  tri- 
angular ganglion,  about  the  size  of  a  pin's  head.  Like  the  other 
ganglia  in  connection  with  the  branches  of  the  fifth  pair,  it  receives 
filaments  of  communication  of  three  different  kinds — viz.  motor, 
sensory,  and  sympathetic.  Its  motor  root  is  the  chorda  tympani, 
derived  from  the  facial  nerve  :  its  sensory  branches  proceed  from 
the  gustatory ;  and  its  connection  with  the  sympathetic  system  is 
established  by  a  branch  which  comes  from  the  nervi  molles  round 
the  facial  artery.  The  ganglion  supplies  five  or  six  branches  of 
distribution  to  the  submaxillary  gland,  its  duct,  and  the  mucous 
membrane  of  the  floor  of  the  mouth.  Meckel  describes  a  small 
branch  of  the  ganglion  which  sometimes  passes  forwards  to  join  a 
branch  of  the  hypoglossal,  on  the  hyo-glossus  m.,  and  ends  in  the 
genio-hyo-glossus . 

LINGUAL  The    lingual    artery  is   generally   the   second 

ARTEHY.  branch  of  the  external  carotid.     Curving  slightly 

upwards  and  inwards  from  its  origin,  the  artery  soon  runs  forwards 
round  the  great  cornu  of  the  hyoid  bone,  beneath  the  posterior 
belly  of  the  digastricus  and  stylo-hyoideus,  and  then  passes 


106  RANINE   VEIN. 

beneath  the  hyo-glossus  m.  parallel  to  the  os  hyoides.  At  the  ante- 
rior edge  of  the  hyo-glossus  it  ascends  to  the  under  surface  of  the 
tongue,  and  is  continued  forwards  to  the  apex  of  the  tongue  under 
the  name  of  ranine.  Before  the  artery  passes  beneath  the  hyo- 
glossus,  it  is  crossed  by  the  hypoglossal  nerve,  but  it  immediately 
after  becomes  separated  from  the  nerve  by  this  muscle.  Under 
the  hyo-glossus  the  artery  lies  upon  the  middle  constrictor  of  the 
pharynx,  and  the  genio-hyo-glossus ;  in  the  substance  of  the 
tongue,  it  lies  between  the  genio-hyo-glossus  and  the  inferior 
lingualis.  The  curves  made  by  the  artery  are  for  the  purpose  of 
allowing  the  elongation  of  the  tongue.  Its  branches  are  : — 

1.  The  hyoid,  a  small  artery  which  runs  along  the  upper  border  of 
the  hyoid  bone,  supplying  the  muscles  and  anastomosing  with  its  fellow, 
and  with  the  hyoid  branch  of  the  superior  thyroid  artery.     The  nerve 
to   the   thyro-hyoid   muscle,   which  is  derived  from   the   hypoglossal, 
accompanies  this  artery. 

2.  The  dorsales  linyuce,  two  or  more,  run  under  the  hyo-glossus  to 
the  back  of  the  tongue,  the  mucous  membrane,  tonsil,  and  soft  palate. 

3.  The   siiblingual,  arising  near  the  anterior  border  of  the  hyo- 
glossus,    supplies   the   sublingual  gland,    the   mylo-hyoideus,    and   the 
mucous   membrane   of   the  mouth  and   gums.     This  artery  generally 
gives  off  the  little  artery  of  the  frsenum   linguae,  which  is  sometimes 
wounded   in   cutting  the   fraenum   in  children  who   are   tongue-tied  ; 
especially  when  we  neglect  the  rule  of  pointing  the  scissors  downwards 
and  backwards. 

4.  The  ranine  is  the  termination  of  the  lingual  artery.     As  it  runs 
forwards  to  the  tip  of  the  tongue  along  the  outer  side  of  the  genio-hyo- 
glossus,  along  with  the  gustatory  nerve,  it  distributes  branches  to  the 
tongue,   and   at  the  tip  inosculates   slightly    with  its   fellow   of   the 
opposite  side. 

The  ranine  vein,  commencing  at  the  tip  of  the  tongue,  after  join- 
ing with  the  venae  comites  of  the  lingual  artery  and  the  dorsal 
veins  of  the  tongue,  runs  along  its  under  surface  over  the  hyo- 
glossus,  and  terminates  in  the  internal  jugular  or  facial  vein. 

The  best  place  for  finding  and  tying  the  lingual  artery  has 
been  mentioned  (p.  100).  The  rule  laid  down  is  trustworthy  only 
when  the  artery  runs  its  normal  course.  We  have  known  an 
instance  in  which  a  good  anatomist  failed  in  an  attempt  to  tie  the 


OCCIPITAL   ARTERY.  107 

lingual  artery,  because  the  vessel  arose  from  the  facial  behind  the 
submaxillary  gland,  and  then  passed  through  the  mylo-hyoideus 
to  reach  the  tongue. 

OCCIPITAL  The  occipital  artery  arises  from  the  posterior 

ARTERY.  part  of  the  external   carotid,  usually  opposite  the 

facial  artery,  and  runs  upwards  and  backwards  along  the  lower 
border  of  the  digastricus  towards  the  mastoid  process.  It  passes 
then  under  the  posterior  belly  of  the  digastricus,  and  further  on  in 
its  course  it  lies  in  the  interval  between  the  transverse  process  of 
the  atlas  and  the  mastoid  process,  close  to  the  rectus  capitis  lateralis ; 
it  now  changes  its  direction,  for  it  runs  horizontally  backwards  in 
the  occipital  groove  of  the  temporal  bone,  under  all  the  muscles 
attached  to  the  mastoid  process — namely,  the  sterno-mastoid,  the 
splenius  capitis,  the  trachelo-mastoid,  and  the  digastricus,  and  it 
lies  on  the  superior  oblique  and  the  com  plexus.  Arrived  at  the 
back  of  the  head,  the  artery  pierces  the  cranial  attachment  of  the 
trapezius,  and  ascending,  divides  into  wide-spreading  branches  for 
the  supply  of  the  scalp. 

In  the  first  part  of  its  course,  the  occipital  artery  crosses  over 
the  internal  carotid  artery,  the  internal  jugular  vein,  the  pneumo- 
gastric  and  the  spinal  accessory  nerves,  and  is  itself  crossed  by  the 
hypoglossal  nerve.  It  sends  off  the  seven  following  branches  : — 

1.  Muscular  branches  to  the  digastric,  stylo-hyoid,  splenius,  and 
trachelo-mastoid  muscles. 

2.  The  superior  sterno-mastoid,  which  enters  the  muscle  with  the 
nervus  accessorius. 

3.  The  auricular  ramifies  on  the  cranial  aspect  of  the  concha. 

4.  The  posterior  meningeal  Ascends  with  the  internal  jugular  vein, 
and  enters  the  cranium  through  the  foramen  jugulare  to  supply  the 
dura  mater  of  the  posterior  fossa. 

5.  The  princeps  cervicis,  which  we  shall  see  better  hereafter,  is  a 
short  trunk  which  runs  down  the  back  of  the  neck,  and  divides  into 
two  branches — a  superficial,  lying  beneath  the  splenius,  and  supplying 
also  the  trapezius,  and  a  deep  branch  lying  under  the  complexus,  and 
anastomosing  with  branches  of  the  vertebral  and  with  the  deep  cervical 
branch  of  the  superior  intercostal  artery  between  this  muscle  and  the 
semi-spinalis  colli. 


108  POSTERIOR  AURICULAR  ARTERY. 

6.  The  mastoid  enters  the  foramen   in  the  mastoid  process,  and 
supplies  the  dura  mater. 

7.  The  cranial  branches  supply  the  scalp  on  its  posterior  aspect, 
and  anastomose  freely  with  the  corresponding  artery  of  the  opposite 
side,  the  posterior  auricular  and  the  superficial  temporal  arteries. 

The  occipital  vein  accompanies  the  artery,  and  is  connected  with 
the  lateral  sinus  through  a  small  vein  running  through  the  mas- 
toid foramen.  It  subsequently  terminates  in  the  internal  jugular, 
occasionally  in  the  external  jugular  vein. 

POSTEKIOB  Au-  The  posterior  auricular  artery,  the  fifth  branch, 
EICULAE  ABTEBY.  js  given  off  from  the  posterior  part  of  the  external 
carotid.  It  arises  above  the  digastricus,  lies  on  the  styloid  process, 
and  under  cover  of  the  parotid  gland  reaches  the  furrow  between 
the  cartilage  of  the  ear  and  the  mastoid  process.  Before  it  reaches 
the  furrow  it  is  crossed  by  the  facial  nerve,1  and  just  beneath  it  is 
the  spinal  accessory.  Above  the  mastoid  process  it  divides  into 
two  branches,  a  posterior  inosculating  with  the  occipital,  and  an 
anterior  communicating  with  the  temporal.  It  supplies  the  back 
of  the  scalp  and  the  cartilage  of  the  ear.  It  gives  off — 

1.  Small  branches  to  the  digastricus,  stylo-hyoid,  and  the  parotid 
gland. 

2.  The  slylo-mastoid,  a   very   constant    little   artery,    which   runs 
through   the  stylo-mastoid  foramen  to  supply  the  mastoid  cells,   the 
vestibule,   and  the  membrana   tyrnpani.      In   young  subjects,  one   of 
these  latter  branches  forms  a  vascular  circle  around  the  circumference 
of  the  membrane  with  the  tympanic  branch  of  the  internal  maxillary. 

3.  The  atiricular  branch  runs  along  the  cranial  surface  of  the  auricle, 
and  anastomoses  with  the  superficial  temporal  and  occipital  arteries. 
Some  of  the  branches  pierce  the  cartilage  of  the  ear  and  ramify  on  its. 
anterior  surface. 

4.  The  mastoid  branch  is  distributed  to  the    structures  over  the 
mastoid  process. 

The  posterior  auricular  vein  is  rather  large,  and  running  over 
the  mastoid  process,  terminates  in  the  external  jugular  vein. 

POSTEEIOK  Au-  The  posterior  auricular  nerve  lies  close  to  the 

BICULAB  NEBVE.        artery  of  the  same  name.     It  is  the  first  branch  of 

1  The  posterior  auricular  artery  frequently  runs  superficial  to  the  facial  nerve. 


CERVICAL   PLEXUS   OF  NERVES.  109 

the  seventh  or  facial  nerve  after  its  exit  from  the  stylo-mastoid 
foramen.  It  runs  behind  the  ear  and  divides  into  an  auricular 
branch  to  the  retrahens  and  the  attollens  aurem,  and  an  occipital 
branch  to  the  posterior  belly  of  the  occipito-frontalis,  which  com- 
municates with  the  small  occipital  nerve.  The  nerve  is  connected 
with  the  great  auricular  nerve  of  the  cervical  plexus,  and  with  the 
auricular  branch  of  the  pneumogastric  nerve. 

ASCENDING  This  long  and  straight  branch  arises  about  half 

PHARYNGEAL  an  inch  above  the  division  of  the  common  carotid. 

ARTERY.  j^  ascends  between  the  internal  carotid  and  the 

side  of  the  pharynx  to  the  base  of  the  skull,  lying  upon  the  rectus 
capitis  anticus  major.  It  gives  off  numerous  branches ;  among 
them  are  : — 

1.  Small  external   branches   which    pass   outwards   to   supply   the 
anterior  recti  muscles,  the  superior  cervical  ganglion,  the  pneumogastric 
and  hypoglossal  nerves,  and  the  prevertebral  lymphatic  glands.     They 
anastomose  with  the  ascending  cervical  artery. 

2.  Pharyngeal  branches,  some    of   which   pass   to   the   two   lower 
pharyngeal  constrictors  and  the  stylo-pharyngeus  :  one,  the  largest  of 
all,  enters  the  pharynx  above  the  superior  constrictor,  and  terminates  in 
the  soft  palate,  the  Eustachian  tube,  and  the  tonsils. 

3.  Meningeal  branches. — One  passes  through  the  foramen  lacerum 
ppsticum,  with  the  internal  jugular  vein,  and  is  distributed  to  the  dura 
mater  of  the   occipital   fossa  ;  another  through  the  foramen  lacerum 
medium,  and  one  through  the  anterior  condylar  foramen.    . 

The  pharyngeal  vein  receives  some  meningeal  branches,  also 
small  veins  from  the  soft  palate,  Eustachian  tube,  and  uniting, 
form  the  pharyngeal  plexus  which  opens  into  the  internal  jugular 
or  common  facial  vein. 

The  examination  of  the  two  remaining  branches  of  the  external 
•carotid,  the  internal  maxillary  and  temporal,  must  for  the  present 
be  postponed.  Meanwhile  the  student  should  make  out  the  deep 
•cervical  plexus  and  its  branches. 

CERVICAL  This  plexus  is  formed  by  the  anterior  branches 

PLEXUS  OF  of  the  four  upper  cervical  nerves.     It  consists  of  a 

NERVES.  series  of  loop-like  communications,  between  these 

nerves,  close  to  the  transverse  processes  of  the  four  upper  cervical 
vertebrae  ;  each  nerve  dividing  into  an  ascending  and  a  descending 


110  DEEP  CERVICAL  PLEXUS. 

branch,  with  the  exception  of  the  first.  The  plexus  rests  on  the 
levator  anguli  scapulas  and  scalenus  medius,  and  is  situated  behind 
the  sterno-mastoid  m.  and  the  internal  jugular  vein. 

The  plexus  gives  off  superficial  and  deep  branches :  the  super- 
ficial coming  from  the  second,  third  and  fourth  nerves,  the  deep  from 
the  third  and  fourth  n.  The  superficial  branches  have  been  already 
described  (p.  68). 

The  deep  branches  may  be  divided  into  an  internal  and  an  ex- 
ternal series. 

INTERNAL  SERIES. — 1.  The  phrenic  arises  from  the  third,  fourth, 
and  fifth  cervical  nerves,  descends  obliquely  inwards  over  the  scalenus 
anticus,  and  then  crosses  over  the  first  part  of  the  subclavian  artery. 
Near  the  thorax  it  is  joined  by  the  sympathetic,  and  frequently  by  a 
looped  branch  from  the  nerve  to  the  subclavius  muscle.  Its  course 
through  the  thorax  to  its  destination  in  the  diaphragm  will  be  described 
p.  112. 

2.  The  communicantes  noni  come  from  the  second  and  third  cervical 
nerves,  wind  round  the  internal  jugular  vein,  and  join  the  descendens 
noni  in  front  of  the  carotid  sheath,  forming  the  '  ansa  hypoglossi.'    They 
supply  the  depressor  muscles  of  the  os  hyoides  and  larynx. 

3.  Muscular  branches  which  proceed  from  the  first  cervical  and  the 
loop  between  it  and  the  second  cervical,  to  the  recti  antici,  the  rectus 
lateralis,  and  longus  colli  muscles. 

4.  Branches  which   communicate   with    the  pneumogastric,    hypo- 
glossal,  and  sympathetic  nerves,  and  one  to  join  the  fifth  cervical. 

EXTERNAL  SERIES. — 1.  One  or  more  comrminicating  branches  to  the 
nervus  accessorius  :  firstly  in  the  sterno-mastoid,  then  in  the  occipital 
triangle,  and  lastly  beneath  the  trapezius. 

2.  Musctilar  branches  to  supply  the  trapezius,  levator  anguli 
scapulae,  scalenus  medius  and  sterno-mastoid.  The  branches  to  the 
trapezius,  levator  anguli  scapulae,  and  scalenus  medius,  come  from  the 
third  and  fourth  ;  the  branch  to  the  sterno-mastoid  from  the  second 
cervical  nerve. 

The  clavicle  should  now  be  sawn  through  the 
DISSECTION. 

middle,    and    the    sternal    half    raised   with   the 

sterno-mastoid  attached,  so  that  the  bone  can  be  replaced,  to  study 
its  relation  to  the  subjacent  parts.  The  scalene  muscles  and  the 
subclavian  artery  throughout  its  whole  course  must  next  be  care- 
fully dissected.  While  this  is  being  done,  the  student  must  be 


SCALENE   MUSCLES.  Ill 

careful  not  to  injure  the  branches  of  the  subclavian  artery,  th& 
lymphatic  duct  on  the  right,  and  the  thoracic  duct  on  the  left  side,, 
the  nerve  to  the  subclavius  m.,  the  phrenic  nerve,  the  cervical 
and  the  brachial  plexuses  of  nerves,  and  their  small  branches. 

SCALENE  The  scalene  muscles,  so  called  from  their  resem- 

MUSCLES.  blance  to  a  scalene  triangle,  extend  from  the  trans- 

verse processes  of  the  cervical  vertebras  to  the  first  and  second  ribs. 
They  may  be  considered  as  intercostal  muscles,  since  the  transverse 
processes  of  the  cervical  vertebras  are  but  rudimentary  ribs.  Anato- 
mists describe  them  as  three  separate  muscles — an  anterior,  a  middle, 
and  a  posterior  ;  the  anterior  and  middle  are  attached  to  the  first 
rib,  the  posterior  to  the  second.  In  plan  and  purpose  these  three 
muscles  are  one. 

SCALENUS  The  scalenus  anticus  is  attached  above  to  the 

ANTICUS.  anterior  tubercles  of  the  transverse  processes  of 

the  third,  fourth,  fifth,  and  sixth  cervical  vertebras,  and  below  by  a 
flat  tendon  to  the  tubercle  on  the  inner  border  and  upper  surface  of 
the  first  rib  in  the  front  of  the  groove  for  the  subclavian  artery. 

SCALENUS  The  scalenus  medius  is  attached  above  to  the 

MEDIUS.  posterior  tubercles  of  the  transverse  processes  of 

all  the  cervical  vertebrae  except  the  first,  and  below  to  the  first  rib 
behind  the  scalenus  anticus,  extending,  from  the  tubercle,  forwards 
for  an  inch  and  a  half. 

SCALENUS  The  scalenus  posticus  is  attached  above  to  the 

POSTICUS.  posterior  tubercles  of  the  transverse  processes  of 

the  two  or  three  lowest  cervical  vertebras,  and  below  to  the  second 
rib  between  its  tubercle  and  angle,  anterior  to  the  levator  costas, 
and  behind  the  serratus  magnus. 

The  scaleni  are  supplied  by  branches  derived  from  the  lower 
cervical  nerves. 

The  scalene  muscles  are  important  agents  in  raising  the  thorax, 
in  a  deep  inspiration.  Take  a  deep  breath,  and  you  can  easily  feel 
them  contracting.  They  can  bend  the  cervical  portion  of  the 
spine,  if  their  lower  attachment  be  the  fixed  point,  as  in  rising 
from  the  recumbent  position. 

The  scalenus  anticus  is  one  of  those  muscles  about  which  we 
ought  to  know  well  all  that  lies  in  front  of  it,  and  all  that  lies- 


112  PHRENIC  NERVE. 

behind  it.  In  the  front  of  it  are,  the  clavicle,  the  subclavius,  the 
clavicular  origin  of  the  sterno-mastoid,  the  omo-hyoid,  the  phrenic 
nerve,  the  subclavian  vein,  the  supra-scapular,  the  posterior  scapu- 
lar, and  the  ascending  cervical  arteries.  Behind  it  are  the  sub- 
clavian artery,  the  five  nerves  which  form  the  brachial  plexus,  and 
the  pleura ;  to  its  inner  side  is  the  internal  jugular  vein,  and  the 
vertebral  artery  separates  it  from  the  longus  Colli. 

Make  your  finger  familiar  with  the  feel  of  the  tubercle  on  the 
first  rib,  to  which  the  scalenus  anticus  is  attached.  This  tubercle 
is  the  guide  to  the  subclavian  artery,  for  it  enables  you  to  find  the 
outer  edge  of  the  scalenus  anticus,  where  you  must  look  for  the 
vessel.  Is  the  scalenus  anticus  entirely  concealed  from  view  by 
the  sterno-mastoid  or  not  ?  This  will  depend  upon  the  breadth  of 
the  clavicular  attachment  of  the  sterno-mastoid.  As  a  general  rule, 
it  may  be  said  that  the  scalene  muscle  is  concealed  by  the  sterno- 
mastoid,  and  that  consequently,  in  tying  the  subclavian  artery,  it  may 
be  necessary  to  divide  partially  the  clavicular  origin  of  the  muscle. 

The  phrenic  nerve  runs  down  in  front  of  the 
PHRENIC  NERVE.  ,  .  ,,  ,  , 

scalenus    anticus,  irom   the   outer   to   the   inner 

border.  It  arises  from  the  third,  fourth,  and  fifth  cervical  nerves, 
but  chiefly  from  the  fourth.  It  enters  the  chest  between  the  sub- 
clavian artery  and  vein,  crosses  in  front  of  the  internal  mammary 
artery,  and  continues  its  course  between  the  pericardium  and 
pleura,  in  front  of  the  root  of  the  lung,  to  the  diaphragm,  which 
it  supplies. 

When  the  spinal  cord  is  injured  above  the  fourth  cervical  ver- 
tebra, the  origin  of  the  phrenic  is  implicated ;  therefore  the  dia- 
phragm, as  well  as  the  other  muscles  of  inspiration,  are  paralysed. 
Death  is  the  immediate  result.1 

1  The  phrenic  nerve  is  joined  by  a  filament  from  the  sympathetic,  and  fre- 
quently by  a  filament  from  that  branch  of  the  brachial  plexus  which  supplies  the 
subclavius  muscle.  This  is  sometimes  a  branch  of  considerable  size,  and  forms 
the  greater  portion  of  the  phrenic  itself.  We  have  met  with  many  instances  in 
which  this  accessory  branch  was  larger  than  the  regular  trunk  ;  in  all  of  them  it 
crossed  over  the  subclavian  artery  in  the  third  part  of  its  course,  and  would  prob- 
ably have  been  injured  in  the  operation  of  tying  this  vessel.  That  such  an  acci- 
dent has  actually  happened  is  reported  by  Bransby  Cooper  in  his  surgical  lectures. 
He  speaks  of  having  injured  this  accessory  branch  of  the  phrenic  in  tying  the  sub- 
clavian artery.  The  patient  had  incessant  spasm  of  the  diaphragm  till  he  died. 


SUBCLAVIAN  ARTERY.  113 


COURSE  AND  RELATIONS  OF  THE  SUBCLAVIAN  ARTERIES. 

The  left  subclavian  artery  differs  from  the  right,  not  only  in 
its  origin,  but  in  the  relations  of  the  first  part  of  its  course.  The 
right  should,  therefore,  be  examined  first,  and  then  the  differences 
between  it  and  the  left. 

EIGHT  SUBCLA-  The  right  subclavian  artery  is  one  of  the  two 

VIAN  ARTEKY.  great  branches  into  which  the  arteria  innominata 

divides  behind  the  sterno-clavicular  joint.  It  runs  outwards  behind 
the  scalenus  anticus,  then  inclines  downwards  over  the  first  rib,  at 
the  outer  border  of  which  it  takes  the  name  of  axillary.  The  artery 
describes  a  curve,  of  which  the  greatest  convexity  is  between  the 
scalene  muscles.  The  height  to  which  the  arch  ascends  varies. 
Generally,  it  rises  higher  in  women  than  in  men,  on  the  right  side 
than  on  the  left. 

To  study  its  relations  more  precisely,  the  course  of  the  sub- 
clavian is  divided  into  three  parts  :  1 .  The  part  which  intervenes 
between  its  origin  and  the  inner  border  of  the  scalenus  anticus. 
2.  That  which  lies  behind  the  scalenus.  3.  That  which  intervenes 
between  the  outer  border  of  the  scalenus  and  the  outer  border  of 
the  first  rib. 

The  first  portion  of  the  artery  lies  deeply  in  the  neck  and  passes 
upwards  and  outwards  to  the  inner  border  of  the  scalenus  anticus. 
It  is  covered  by  the  skin,  platysma,  superficial  and  deep  fasciae,  the 
sternal  end  of  the  clavicle,  the  sterno-inastoid,  sterno-hyoid,  and 
sterno-thyroid  muscles,  and  a  layer  of  deep  fascia,  continued  from 
the  inner  border  of  the  scalenus  anticus.  It  is  crossed  by  the 
internal  jugular  and  vertebral  veins,  by  the  pneumogastric  and 
phrenic  nerves,  and  by  some  cardiac  filaments  of  the  sympathetic. 
Inferiorly  it  rests  upon  the  pleura.  Behind  the  artery  are  the 
recurrent  branch  of  the  pneumogastric,  the  sympathetic  nerve,  the 
longus  colli,  the  transverse  process  of  the  seventh  cervical  vertebra 
and  the  apex  of  the  lung  covered  with  the  pleura.  The  subclavian 
vein  lies  below  the  artery.  Three  branches  arise  from  this  portion 
of  the  subclavian — viz.  the  vertebral,  internal  mammary,  and  thyroid 
axis. 


114 


SUBCLAVIAN   ARTERY. 


In  the  second  (the  highest)  part  of  its  course,  the  artery  lies 
between  the  scalene  muscles.  It  is  covered  by  skin,  platysma,  and 
superficial  fascia,  by  the  clavicular  origin  of  the  sterno-inastoid,  the 
deep  cervical  fascia,  and  by  the  scalenus  anticus  and  phrenic  nerve 


FIG.  30. 


3rd  cervical  n.    — . 


4th  cervical  n. 
Piieumogas- 
tric  n.  .    .    . 


5th  cervical  n. 


Brachial  plexus 


Phrenic  n.  .    . 


Line  of  reflec- 
tion of  peri- 
cardium. 


Cervicalis  ascendens  a. 
Scalenus  anticus. 
Inferior  thyroid  a. 

Superficialis  colli  a. 
Phrenic  n. 

Posterior  scapular  a. 
Supra-scapular  a. 
Subclavian  a. 
Superior  intercostal  a. 
Internal  mammary  a. 
Pneumogastric  n. 

Phrenic  n. 

Appendix  of  left  auricl* 


which  separate  it  from  the  subclavian  vein.  Behind  the  artery  is 
the  scalenus  medius ;  above  it,  is  the  brachial  plexus ;  below  it,  is 
the  pleura.  Only  one  branch,  the  superior  intercostal,  is  given  off 
from  this  part  of  the  artery. 


LEFT  SUBCLAVIAN  ARTERY.  115 

In  the  third  part  of  its  course,  the  artery  passes  downwards 
and  outwards,  and  lies  in  the  supra-clavicular  triangle  upon  the 
surface  of  the  first  rib.  Here  it  is  most  superficial,  and  is  covered 
by  the  skin,  platysma,  the  two  layers  of  the  cervical  fascia,  and 
the  clavicular  branches  of  the  superficial  cervical  plexus ;  subse- 
quently by  the  suprascapular  artery  and  vein,  the  clavicle,  the 
subclavius  muscle,  with  its  nerve ;  and,  what  is  of  much  more 
consequence,  it  is  here  crossed  by  the  external  jugular  and 
(often)  the  supra  and  posterior  scapular  veins ;  so  that  there 
is  here  a  confluence  of  large  veins  in  front  of  the  artery.  The 
subclavian  vein  is  situated  below  the  artery,  but  on  a  plane  an- 
terior to  it.  Beloiv  it,  is  the  first  rib,  and  behind  it  the  scalenus 
medius.  Above  the  artery,  and  to  its  outer  side,  are  •  the  trunk 
nerves  of  the  brachial  plexus  and  the  omo-hyoid  m.  One  of  these 
nerves  (the  conjoined  fifth  and  sixth  cervical)  runs  so  nearly  paral- 
lel with  the  artery,  and  on  a  plane  anterior  to  it,  that  it  is  quite 
possible  to  mistake  the  nerve  for  the  artery,  in  the  operation  of 
tying  it.  We  have  heard  a  hospital  surgeon  of  great  experience 
say,  that  he  had  seen  this  mistake  committed  on  three  separate 
occasions.  In  this  part  of  its  course,  the  artery  as  a  rule  gives  off' 
no  branches;  the  most  frequent  exceptions  are  the  posterior 
scapular,  and  supra-scapular. 

LEFT  SUBCLA-  The  left  subclavian  is  the  last  of  the  three  great 

VIAN  AKTEKY.  branches  which  arise  from  the  arch  of  the  aorta. 

It  ascends  nearly  vertically  out  of  the  chest,  and  then  arches  in 
front  of  the  apex  of  the  lung  and  pleura  to  reach  the  inner  border 
of  the  scalenus  anticus,  behind  which  it  runs  over  the  first  rib. 

In  the  first  part  of  its  course  the  left  subclavian  lies  deeply  in 
the  chest,  near  the  spine.  On  its  outer  or  left  side  it  is  covered  by 
the  pleura ;  on  its  inner  or  right  side  are  at  first  the  trachea,  then 
the  oesophagus  and  thoracic  duct ;  in  front  are  the  left  lung,  covered 
with  its  pleura,  the  pneumogastric  and  phrenic  nerves,  and  the 
cardiac  branches,  all  of  which  lie  parallel  with  the  artery,  the  left 
common  carotid,  and  the  left  brachio-cephalic  vein ;  at  the  level  of 
the  upper  part  of  the  chest  it  has  in  front  the  sterno-thyroid, 
sterno-hyoid,  the  sterno-mastoid  muscles,  the  left  internal  jugular 
and  vertebral  veins,  and  the  sternal  end  of  the  clavicle ;  behind  it 

i  2 


116  LEFf  SUBCLAVIAN  ARTEKY. 

are  the  longus  colli,  the  vertebral  column,  the   inferior  cervical 

ganglion  of  the  sympathetic,  the  oesophagus,  and  the  thoracic  duct. 

Behind  the  scalenus  anticus,  and  on  the  surface  of  the  first  rib, 

the  relations  of  the  left  subclavian  are  similar  to  those  of  the  right 

(P-  H4). 

The  left  subclavian,  then,  differs  from  the  right  only  in  the  first 
part  of  its  course.  Now,  what  are  these  differences  ? 

1.  The  left  subclavian  comes  direct  from  the  arch  of  the  aorta, 
and  is  therefore  longer,  deeper  in  the  chest,  and  more  vertical  than 
the  right,  which  comes  from  the  arteria  innominata. 

2.  The  left  subclavian  is  in  close  relation  with  the  oesophagus 
and  the  thoracic  duct :  the  right  is  not. 

3.  The  left  subclavian  is  crossed  by  the  left  brachio-cephalic 
vein. 

4.  The  left    subclavian  has  the  phrenic,  pneumogastric,   and 
cardiac  nerves  nearly  parallel  with  it ;  on  the  right  side,  these 
nerves  cross  the  artery  at  a  nearly  right  angle. 

5.  The  left  subclavian  is  not  embraced  by  the  recurrent  laryn- 
geal  nerve,  like  the  right  subclavian. 

The  thoracic  duct  bears  an  important  relation  to  the  left  sub- 
clavian. It  ascends  from  the  chest  to  .the  left  of  the  oesophagus 
and  behind  the  artery ;  then  arching  behind  the  internal  jugular 
vein  as  high  as  the  seventh  cervical  vertebra,  it  curves  downwards 
and  forwards  in  front  of  the  scalenus  anticus  to  terminate  in  the 
subclavian  vein  at  its  junction  with  the  jugular.  The  duct  is  so 
thin  and  transparent  that  it  easily  escapes  observation ;  it  is  most 
readily  found  by  raising  the  subclavian  vein  near  its  junction  with 
the  jugular,  and  searching  with  the  handle  of  the  scalpel  on  the 
inner  side  of  the  scalenus  anticus,  in  front  of  the  vertebral  vein. 

Before  tracing  the  branches  of  the  subclavian  artery,  consider 
some  points  relating  to  the  operation  of  tying  it. 

To  tie  the  artery  in  the  first  part  of  its  course,  namely,  on  the 
inner  edge  of  the  scalenus  anticus,  is  an  operation  of  great  difficulty 
and  danger,  even  with  the  parts  in  a  normal  position.  The  great 
depth  at  which  the  artery  is  placed,  the  size  and  close  proximity 
of  its  numerous  branches,  the  large  veins  by  which  it  is  covered, 
its  connection  with  the  pneumogastric,  recurrent  laryngeal,  phrenic, 


LIGATURE   OF   THE   SUBCLAVIAN   ARTERY.  117 

and  sympathetic  nerves,  and,  above  all,  its  close  contiguity  with 
the  pleura,  form  a  combination  of  circumstances  so  formidable  that 
one  cannot  be  surprised  the  operation  has  never  been  performed 
with  a  favourable  result.  On  the  left  side  the  operation  is  more 
difficult  to  perform  than  on  the  right,  owing  to  the  difference  in 
the  anatomical  relation  of  the  two  sides. 

In  the  second  part  of  its  course,  between  the  scalene  muscles, 
the  artery  is  more  accessible,  although  it  is  rarely  ligatured  in  this 
situation.  It  would  be  necessary  to  divide  the  clavicular  origin  of 
the  sterno-mastoid,  the  cervical  fascia,  and  the  scalenus  anticus,  to 
reach  the  vessel ;  the  phrenic  nerve  and  the  subclavian  vein  would 
be  the  chief  objects  exposed  to  injury.  This  operation  was  per- 
formed first  and  with  success  by  Dupuytren  in  the  year  1819. 
More  recently  it  has  been  performed  by  Dr.  Warren,  of  Boston. 
The  patient  recovered,  though  the  pleura  was  wounded.1 

But  in  the  last  part  of  its  course,  that  is,  on  the  outer  side  of 
the  scalenus,  the  artery  may  be  tied  with  comparative  facility. 
The  incision  should  be  made  from  three  to  four  inches  in  length, 
parallel  with  the  upper  border  of  the  clavicle.  We  divide  the 
platysma,  some  of  the  supra-clavicular  nerves,  and  the  cervical 
fascia.  The  external  jugular  vein  and  its  tributaries  must  be 
drawn  to  the  outer  side,  or  divided  and  tied  at  both  ends. 

The  connective  tissue  should  now  be  carefully  cut  through,  and 
the  posterior  belly  of  the  omo-hyoid  sought  for,  as  it  runs  just 
above  the  clavicle.  After  clearing  away  some  fat  and  cellular 
tissue,  the  outer  border  of  the  scalenus  anticus  must  be  felt  for, 
behind  which  the  artery  will  be  found  lying  upon  the  first  rib. 
The  operator  now  passes  his  finger  downwards  along  the  outer 
border  of  this  muscle,  as  far  as  its  insertion  into  the  tubercle  of  the 
first  rib,  which  can  always  be  distinctly  felt.  The  artery  having 
been  exposed  by  carefully  dividing  a  layer  of  fascia  immediately 
covering  the  vessel,  the  ligature  is  to  be  passed  round  the  artery 
from  above  downwards,  care  being  taken  not  to  include  in  the 
ligature  one  of  the  cords  of  the  brachial  plexus. 

Mr.  Ramsden,  of  St.  Bartholomew's  Hospital,  was  the  first  who 
tied  the  subclavian  in  the  third  part  of  its  course,  in  the  year 
1  Med.  Chirurg.  Trans,  vol.  xxix.  p.  25. 


118          BRANCHES  OF  THE  SUBCLAVIAN  ARTERY. 

1809  ;  since  that  time  the  operation  has  been  repeatedly  performed, 
with  very  favourable  results. 

In  the  hands  of  a  surgeon  possessed  of  a  practical  knowledge 
of  anatomy  the  operation  is  easy,  provided  all  circumstances  be 
favourable :  but  circumstances  are  often  very  unfavourable.  Ana- 
tomical deviations  are  by  no  means  rare,  and  it  often  happens  that 
the  aneurismal  or  other  tumour,  on  account  of  which  the  operation 
is  performed,  raises  the  clavicle  beyond  its  natural  level,  and  so 
disturbs  the  parts,  that  to  expose  the  artery  and  place  'a  ligature 
around  it  becomes  exceedingly  difficult.  Under  such  circumstances 
one  cannot  be  surprised  that  even  distinguished  anatomists  have 
committed  mistakes.  Sir  Astley  Cooper  l  failed  in  one  instance. 
Dupuytren  perforated  the  artery  with  the  point  of  the  needle,  and 
included  one  of  the  nerves  in  the  ligature  :  fatal  haemorrhage  was 
the  result.2  We  were  present  at  an  operation  in  which  the  large 
nerve  (a  branch  of  the  brachial  plexus)  which  runs  parallel  with 
and  on  a  plane  anterior  to  the  artery  was  mistaken  for  it  and  tied ; 
the  surgeon  being  deceived  by  the  pulsation  communicated  to  the 
nerve. 

The  description  of  the  means  whereby  the  collateral  circulation 
is  maintained  is  deferred  until  the  branches  of  the  subclavian  have 
been  made  out  and  described. 

BRANCHES  OP  r^ne  branches  of  the  subclavian  extend  so  wide- 

THE  SUBCLAVIAN        ly,  that  in  the   present  dissection  we    can  trace 
ARTERY.  them  only  for  a    short  distance.     They  are  four 

in  number: — 

1.  The  vertebral. 

2.  The  thyroid  axis,  a  short  thick  trunk  which  gives  off  the 
inferior  thyroid,  supra-scapular,  and  posterior  'scapular. 

3.  The  internal  mammary. 

4.  The    superior   intercostal,  which  gives  off  the  deep  cervi- 
cal. 

As  a  rule,  the  vertebral,  the  thyroid  axis,  and  the  internal 
mammary  are  given  off  from  the  subclavian  in  the  first  part  of 
its  course,  and  the  superior  intercostal  in  the  second  part.  The 

1  London  Medical  Eeview,  vol.  ii.  p.  300. 

2  Edinburgh  Med.  and  Surg.  Journal,  vol.  xvi.  1820. 


SUBCLAVIAN   VEIN.  123 

vein  terminates  on  the  right  side  in  the  vena  azygos  major ;  on 
the  left  in  the  brachio-cephalic. 

DEEP  CERVICAL          This  artery  arises  from  the  superior  intercostal, 
ARTEKY.  seldom  direct  from  the  subclavian.     It  goes  to  the 

back  of  the  neck  between  the  first  rib  and  the  transverse  process 
of  the  seventh  cervical  vertebra,  and  ascends  between  the  com- 
plexus  and  the  semi-spinalis  colli,  both  of  which  it  supplies.  It 
sometimes  inosculates  with  the  princeps  cervicis,  a  branch  of  the 
occipital  (p.  107). 

To  test  your  knowledge  of  the  branches  of  the  subclavian 
artery,  reflect  upon  the  answer  to  the  following  question  :  '  If  the 
artery  were  tied  in  the  first  part  of  its  course  before  it  gives  off 
any  branches,  how  would  the  arm  be  supplied  with  blood  ?  '  The 
answer  is,  by  six  collateral  channels,  as  follow ;  1 .  By  the  communi- 
cations between  the  superior  and  inferior  thyroid  ;  2.  Between  the 
two  vertebral ;  3.  Between  the  internal  mammary  and  the  inter- 
costals  and  the  epigastric ;  4.  Between  the  thoracic  branches  of 
the  axillary,  and  the  intercostal  branches  of  the  aorta  ;  5.  Between 
the  superior  intercostal  and  the  aortic  intercostals ;  6.  Between 
the  princeps  cervicis  and  the  deep  cervical.  Most  of  these  inoscu- 
lations are  shown  in  the  diagram  (p.  122). 

Again,  if  the  subclavian  were  tied  in  the  third  part  of  its  course, 
the  circulation  would  be  carried  on  by  the  communications  :  1 .  Be- 
tween the  supra-scapular  and  the  dorsalis  scapulas,  a  branch  of  the 
subscapular  ;  2.  Between  the  supra-acromial  branch  of  the  supra- 
scapular  and  the  acromio-thoracic ;  3.  Between  the  posterior  scapular 
and  the  subscapular  and  dorsalis  scapulae  ;  4.  Between  the  internal 
mammary,  the  aortic  intercostals  and  superior  intercostal  on  the 
one  hand,  and  the  long  and  short  thoracic  branches  of  the  axillary, 
on  the  other. 

SUBCLAVIAN  The  subclavian  vein  does  not  form  an  arch  like 

VEIN,  the  artery,  but  proceeds  in  a  nearly  straight  line 

over  the  first  rib  to  join  the  internal  jugular.  It  extends  from  the 
outer  margin  of  the  first  rib  to  midway  between  the  inner  border 
of  the  scalenus  anticus  and  the  sterno-clavicular  articulation, 
where  it  joins  the  internal  jugular  to  form  the  brachio-cephalic 
vein.  Throughout  its  whole  course  the  vein  is  situated  on  a  plane 


124  BRACHIAL  PLEXUS  OF  NERVES. 

anterior  to  and  a  little  lower  than  the  artery,  from  which  it  is 
separated  by  the  scalenus  anticus,  the  phrenic  and  pneumogastric 
nerves.  It  has  a  pair  of  valves  just  before  its  junction  with  the 
internal  jugular.  It  receives  the  anterior  jugular,  the  external 
jugular,  and  through  it,  the  supra-scapular  and  posterior  scapular 
veins. 

BRACHIAL  The  large  nerves  forming  the  plexus  which  sup- 

PLEXTJS  OF  plies  the  upper  extremity  are  the  anterior  divisions 

NERVES.  of  the  four  lower  cervical  and  the  larger  portion 

of  the  first  dorsal,  with  a  small  fasciculus  derived  from  the  fourth 
cervical  nerve.  Emerging  from  the  intervertebral  foramina  the 
nerves  appear  between  the  anterior  and  middle  scalene  muscles, 
and  pass  with  the  subclavian  artery  into  the  axilla.  In  the  neck 
the  nerves  have  no  plexiform  arrangement,  and  it  is  only  in  the 
axilla  that  they  branch  and  communicate  largely  with  each  other, 
and  form  the  brachial  plexus  of  nerves.  The  nerves  in  the  neck 
are  wide  and  are  situated  higher  than  the  subclavian  artery,  and 
nearly  on  the  same  plane ;  but  as  they  descend  beneath  the  clavicle, 
they  converge  and  form  large  communications;  with  each  other, 
thus  constituting  the  brachial  plexus  which  completely  surrounds 
the  artery  :  one  cord  lying  to. the  outer  side,  a  second  lying  to  the 
inner  side,  and  a  third  behind  the  vessel. 

The  plexus  is  crossed  superficially  by  the  omo-hyoid  muscle, 
and  by  the  supra-scapular  and  posterior  scapular  arteries,  and  their 
corresponding  veins. 

The  arrangement  of  the  nerves  in  the  formation  of  the  plexus 
is  very  variable,  and  often  not  alike  on  both  sides.  The  most 
usual  arrangement  is,  that  at  the  outer  border  of  the  scalenus 
anticus,  the  fifth  and  sixth  cervical  nerves  unite  to  form  an  upper 
trunk  ;  the  eighth  and  the  first  dorsal  n.  form  a  lower  trunk ;  the 
seventh  cervical  runs  for  some  distance  alone,  and  forms  a  middle 
trunk.  Now  each  of  these  four  upper  primary  nerves  divides  into 
an  anterior  and  a  posterior  branch  :  the  anterior  branches  given  off 
from  the  fifth,  sixth,  and  seventh  form  the  outer  cord  of  the  plexus ; 
the  anterior  branches  given  off  from  the  eighth  cervical  and  first 
dorsal  form  the  inner  cord ;  while  the  posterior  branches  of  all  the 


BRANCHES  OF  THE  BRACHIAL  PLEXUS.  125 

nerves  (namely,  the  fifth,  sixth,  seventh,  and  eighth  cervical)  unite 
to  form  the  posterior  cord.1 

The  branches  arising  from  the  plexus  are  best  arranged  into 
those  given  off  above  the  clavicle,  and  those  given  off  below  it. 
The  following  are  those  given  off  above  the  clavicle. 

FIG.  32. 


DIAGRAM    OF   THE    FORMATION    OF    THE    BBACHIAL    PLEXUS    AND    ITS    BRANCHES. 

C  4-8.  Anterior  trunks  of  the  cervical  nerves.  17.  Lesser  int.  cutaneous. 

D  1.  Anterior  trunk  of  the  first  dorsal  n.  18.  Musculo-cutaneous. 

9.  N.  to  the  rhomboid  m.  19.  Circumflex. 

10.  Supra-scapular.  20.  Median. 

11.  N.  to  subclavius  m.  21.  Musculo-zpiral. 
12-13.  Anterior  thoracic.  22.  Ulnar. 

14, 15, 16.  Subscapular  n.  23.  Int.  cutaneous. 

24.  Ext.  respiratory  of  Bell. 

a.  The  branch  forming  one  of  the  roots  of  the  phrenic  arises 
from  the  fifth  cervical.     (Not  in  the  diagram.) 

b.  Nerve  to  the  subclavius  m. — This  proceeds  from  the  fifth  and 
sixth  cervical,  and  crosses  the  subclavian  artery  in  the  third  part 

1  Very  frequently  the  posterior  branch  of  the  eighth  cervical  nerve  does  not, 
stricfly  speaking,  form  part  of  the  posterior  cord,  but  is  continued  on  as  a  separate 
fasciculus  to  form  part  of  the  musculo-spiral  nerve.  For  a  description  of  the 
arrangement  of  the  nerves  constituting  the  plexus,  see  a  paper,  by  Lucas,  Guy's 
Hospital  Reports,  1875  ;  also  Turner  in  the  Journal  of  Anatomy,  1872. 


126  BRANCHES  OF  THE  BRACHIAL  PLEXUS. 

of  its  course.     It  frequently  sends  a  filament,  which  passes  in  front 
of  the  subclavian  vein  to  join  the  phrenic  nerve. 

c.  Nerves  to  the  scaleni  and  the  longus  colli  muscles  are  given 
off  from  the  lower  cervical  nerves  as  they  leave  the  inter  vertebral 
foramina. 

d.  Nerve  to  the  rhomboid  muscles. — This  arises  from  the  fifth 
cervical  nerve,  passes   through  the  scalenus  medius,  and  accom- 
panies the   posterior  scapular  artery,  beneath  the  levator  anguli 
scapulae,  which,  as  well  as  the  rhomboid  muscles,  it  supplies. 

e.  The  supra-scapular  nerve  arises  from  the  cord  formed  by  the 
fifth  and  sixth  cervical  n.,  runs  to  the  upper  border  of  the  scapula, 
where  it  meets  with  the  corresponding  artery,  and  then  passes 
through  the  notch  in  the  scapula.     In  the  supra-spinous  fossa  it 
gives  off  two   branches  to  the  supra-spinatus  m.  and  an   upper 
articular   branch  to  the  shoulder;    it  then  descends   behind  the 
acromion  process  to  the  infra-spinous  fossa,  distributing  a  branch 
to  the  infra-spinatus  muscle,  and  a  lower  articular  filament  to  the 
shoulder  joint. 

f.  The  posterior  thoracic  nerve  (called  external  respiratory  by 
Sir  C.  Bell)  to  the  serratus  mar/nus  arises  from  the  fifth  and  sixth 
cervical  (sometimes  also  from  the  seventh)  in  the  substance  of  the 
scalenus  medius.     It  passes  through  this  muscle  and  subsequently 
emerges  below  the  rhomboid  nerve  ;  it  then  descends  behind  the 
brachial    plexus  and  the  subclavian  vessels  to  the  outer    surface 
of  the  serratus  magnus,  to  the  several  digitations  of  which  it  is 
exclusively  distributed. 

cj.  An  articular  branch  is  distributed  to  the  shoulder  joint ; 
besides  some  filaments  to  the  constituent  bones. 

It  only  remains  to  be  observed  that  the  upper  cord  of  the 
brachial  plexus  receives  a  branch  from  the  lower  cord  of  the  cer- 
vical, and  that  each  of  its  component  nerves  communicates  by 
slender  filaments  with  the  sympathetic. 

Below  the  clavicle  the  plexus  gives  off  branches  for  the  supply 
of  the  arm  ;  namely,  from  the  outer  cord,  the  external  anterior 
thoracic  (to  the  pectoralis  major),  the  musculo-cutaneous,  and  the 
outer  head  of  the  median ;  from  the  inner  cord,  the  internal 
anterior  thoracic  n.  (to  the  pectoralis  minor),  the  inner  head  of 


TEMPORAL   AND   PTERYGO-MAXILLARY  REGIONS.  127 

the  median,  the  ulnar,  the  internal  cutaneous,  and  the  lesser  in- 
ternal cutaneous  (nerve  of  Wrisberg)  nerves ;  from  the  posterior 
cord,  the  three  subscapular  (to  the  subscapularis,  the  latissimus 
dorsi,  and  teres  major),  the  circumflex  (to  the  deltoid  and  teres 
minor)  and  the  musculo-spiral  nerves :  all  of  which  will  be 
described  more  fully  in  the  dissection  of  the  upper  extremity. 


TEMPOEAL  AND  PTEEYGO-MAXILLAEY  EEGIONS. 

In  this  dissection,  the  parts  should  be  examined  in  the  following 
order : — 

1.  Superficial  and  deep  fasciae.  6.  Pterygoid  muscles. 

2.  Superficial  arteries  and  nerves  of  7.  Internal  maxillary  artery  and 

the  temple.  branches. 

3.  Masseter  muscle.  8.  Inferior  maxillary  nerves  and 

4.  Temporal  aponeurosis.  branches. 

5.  Temporal  muscle. 

To  expose  the  temporal  region,  the  skin  of  the  temple  should 
be  reflected  from  below  upwards.  Beneath  the  skin  you  come 
upon  a  layer  of  tough  connective  tissue,  continuous,  above,  with 
the  aponeurosis  of  the  scalp ;  below,  with  the  fascia  covering  the 
masseter  and  the  parotid  gland.  In  this  tissue  are  contained  the 
superficial  temporal  vessels  and  nerves. 

TEMPORAL  This  is  the  smaller  of  the  two  terminal  branches 

ARTERY.  of  the  external  carotid.     Arising  in  the  substance 

of  the  parotid  gland  near  the  neck  of  the  jaw,  it  passes  over 
the  root  of  the  zygoma,  close  to  the  meatus  auditorius  externus, 
ascends  for  about  1^  inches  on  the  temporal  fascia,  and  there 
divides  into  an  anterior  and  a  posterior  branch.  Above  the 
zygoma  it  is  superficial,  being  covered  only  by  the  attrahens 
aurem  and  a  strong  layer  of  fascia;  here  it  is  accompanied  by 
branches  of  the  facial  nerve,  and  by  the  auriculo-temporal  branch 
of  the  inferior  division  of  the  fifth  nerve.  It  gives  off  the  following 
branches  : — 

a.  Several  small  branches  to  the  parotid  gland,  the  temporo-maxil- 
lary  articulation,  and  the  masseter. 


128  AURICULO-TEMPORAL   NERVE. 

b.  The  transversalis  faciei  (p.  41). 

c.  The  anterior  auricular  branches,  two  in  number,  superior  and 
inferior,  ramify  on  the  front  of  the  pinna  of  the  ear,  inosculating  with 
branches  of  the  posterior  auricular. 

d.  The  middle  temporal,  a  small  vessel  given  off  while  the  artery  is 
still  in  the  parotid  gland,  pierces  the  temporal  fascia  above  the  zygoma, 
and  running  in  the  substance  of  the  temporal  muscle,  anastomoses  with 
the  temporal  branches  of  the  internal  maxillary. 

Of  the  two  branches  into  which  the  temporal  divides,  the  anterior 
runs  tortuously  towards  the  external  angle  of  the  frontal  bone,  distant 
from  it  about  an  inch.  Its  ramifications  extend  over  the  forehead, 
supplying  the  orbicularis  and  occipito-frontalis  m.,  and  inosculate  with 
the  supra-orbital  and  frontal  arteries.  The  posterior  runs  towards  the 
back  of  the  head,  and  inosculates  freely  with  the  occipital  and  posterior 
auricular.  The  anterior  branch,  although  the  smaller,  is  usually  selected 
for  arteriotoiny,  the  posterior  being  covered  by  a  strong  and  unyielding 
fascia. 

The  temporal  vein  is  formed  by  the  junction  of  the  veins  accom- 
panying the  terminal  branches  of  the  temporal  artery,  which  are 
situated  superficial  to  the  arteries;  just  above  the  zygoma  it  is 
joined  by  the  middle  temporal  vein  which  takes  its  origin  from  a 
plexus  in  the  temporal  fossa.  The  common  temporal  vein,  formed 
by  the  union  of  these  three  veins,  passes  over  the  zygoma,  enters 
the  parotid  gland,  and  joins  the  internal  maxillary  vein  to  form  the 
temporo-maxillary  vein. 

AURICULO-TEM-          This  nerve  supplies  the  temple  and  side  of  the 
poBAi  NEKVE.  head  with  common  sensation.    It  arises,  close  to  the 

foramen  ovale,  from  the  third  division  of  the  fifth  pair  by  two  roots 
(between  which  the  middle  meningeal  artery  runs).  From  its 
origin  it  proceeds  outwards  beneath  the  external  pterygoid,  between 
the  neck  of  the  jaw  and  the  internal  lateral  ligament.  It  then 
ascends  beneath  the  parotid,  over  the  root  of  the  zygoma,  where 
it  accompanies  the  temporal  artery,  and  divides,  like  it,  into  an 
anterior  and  a  posterior  branch. 

The  posterior  branch  is  the  smaller  of  the  two ;  the  anterior 
forms  communications  with  the  temporal  branches  of  the  facial, 
and  the  orbital  branch  of  the  superior  maxillary.  The  ramifications 
of  the  nerve  correspond  with  those  of  the  artery. 


TEMPORAL   REGION.  129 

Near  their  origin  the  roots  of  the  nerve  are  connected  by  fine 
filaments  with  the  otic  ganglion,  and  close  to  the  condyle  of  the 
jaw  the  nerve  sends  round  the  external  carotid  artery  two  com- 
municating brandies  to  the  temporo-facial  branch  of  the  facial  nerve. 
It  here  distributes  parotid  brandies  to  the  gland ;  articular  brandies 
to  the  temporo-maxillary  articulation,  to  the  meatus  auditorius  and 
the  membrana  tympani.  Above  the  zygoma  it  gives  off  two  auri- 
cular filaments ;  the  upper  ramifies  in  the  skin  of  the  outer  aspect 
of  the  ear,  mainly  on  the  tragus  and  upper  half  of  the  auricle ; 
the  lower  supplies  the  lobule  and  lower  part  of  the  pinna. 

Lastly,  in  the  subcutaneous  tissue  of  the  temple,  we  find  the 
temporal  branches  of  the  facial  nerve,  which  supply  the  frontalis, 
the  attrahens  aurem,  the  orbicularis  palpebrarum,  tensor  tarsi,  and 
corrugator  supercilii. 

MASSETEB  This  muscle  arises  from  the  lower  edge  of  the 

MOSCLE.  zygoma,  and  is  inserted  into  the  outer  side  of  the 

ramus  and  coronoid  process  of  the  jaw.  The  masseter  is  composed 
of  superficial  and  deep  fibres  which  cross  like  the  letter  X.  The 
superficial  fibres,  constituting  the  principal  part  of  the  muscle, 
arise  from  the  anterior  two-thirds  of  the  zygoma  and  the  malar 
process  of  the  superior  maxilla,  by  tendinous  fibres  which  occupy 
the  front  border  of  the  muscle,  and  send  aponeurotic  partitions  into 
its  substance.  These  fibres  pass  downwards  and  backwards,  this 
direction  giving  them  greater  advantage,  and  are  inserted  into  the 
angle  and  part  of  the  ramus  of  the  jaw.  The  deep  fibres,  mainly 
muscular  (which  are  concealed  by  the  parotid  gland),  arise  from 
the  posterior  third  of  the  zygoma,  incline  forwards,  and  are  in- 
serted into  the  upper  half  of  the  ramus  and  the  coronoid  process. 
Besides  these,  a  few  fibres,  arising  from  the  inner  surface  of  the 
zygoma,  are  inserted  into  the  coronoid  process  and  the  tendon  of 
the  temporal  muscle.  Its  action  is  to  raise  the  jaw  and  help  to 
masticate  the  food.  Its  nerve  comes  from  the  inferior  maxillary. 

The  following  objects  lie  superficial  to  the  masseter :  1 . 
Zygomatici  major  and  minor;  2.  Orbicularis  palpebrarum;  3. 
Glandula  socia  parotidis  and  parotid  duct ;  4.  Transversalis  faciei 
artery ;  5.  Facial  artery  and  vein ;  6.  Branches  of  the  facial 
nerve. 

K 


130  TEMPORAL   MUSCLE. 

TEMPORAL  This    strong    shining    aponeurotic    membrane 

FASCIA.  covers  the  temporal  muscle ;  its  chief  use  being 

to  give  additional  origin  to  its  fibres.  It  is  attached  above  to  the 
temporal  ridge,  and  increasing  in  thickness  as  it  descends,  divides 
near  the  zygoma  into  two  layers,  which  are  attached  to  the  outer 
and  inner  borders  of  the  zygomatic  arch.  These  layers  are 
separated  by -fat,  in  which  is  found  a  filament  from  the  orbital 
branch  of  the  superior  maxillary  nerve,  and  the  orbital  branch  of 
the  temporal  artery.  The  density  of  this  aponeurosis  explains 
why  abscesses  in  the  temporal  fossa  rarely  point  outwards ;  the 
pus  generally  makes  its  way,  beneath  the  zygoma,  into  the 
mouth. 

Reflect  the  aponeurosis,  and  notice  that  it  is  separated  from  the 
temporal  muscle,  near  the  zygoma,  by  fat.  The  absorption  of  this 
fat,  and  the  wasting  of  the  muscle,  occasion  the  sinking  of  the 
temple  in  emaciation  and  old  age. 

Divide  the  zygomatic  arch  on  each  side  of  the 
DISSECTION 

masseter,  and  turn  it  downwards,  taking  care  of  the 

masseteric  nerve  and  artery  which  enter  its  under  aspect.  Observe 
the  direction  of  the  superficial  and  deep  fibres,  and  the  tendinous 
partitions  whicll  augment  the  power  of  the  muscle  by  increasing 
its  extent  of  origin.  The  masseteric  nerve  and  artery  enter  the 
under  surface  of  the  muscle  near  to  its  posterior  border,  through 
the  sigmoid  notch  of  the  jaw ;  the  artery  comes  from  the  internal 
maxillary,  the  nerve  from  the  motor  division  of  the  inferior 
maxillary. 

TEMPOBAL  This  broad  fan-shaped  muscle  arises  from  the 

MUSCLE.  whole  of  the  temporal  fossa  (except  the  malar  sur- 

face) and  the  deep  surface  of  the  temporal  fascia.  Its  fibres 
converge  to  a  strong  tendon,  which  is  inserted  into  the  inner  sur- 
face, the  apex,  and  anterior  border  of  the  coronoid  process,  as  far 
forwards  as  the  last  molar  tooth. 

The  fibres  of  the  muscle,  converging  from  their  wide  origin,  pass 
under  the  zygomatic  arch,  and  terminate  upon  their  tendon,  the 
outer  surface  of  which  is  partially  concealed  by  the  insertion  of  those 
fibres  which  come  from  the  temporal  aponeurosis  :  remove  them,  and 
see  how  this  tendon  radiates  into  the  muscle  like  the  ribs  of  a  fan. 


PTERYGO-MAXILLARY   REGION.  131 

Its  nerves  (two  deep  temporal)  are  branches  of  the  inferior  maxillary 
(p.  139). 

Between  the  posterior  border  of  this  muscle  and  the  neck  of 
the  inferior  maxilla,  the  masseteric  nerve  and  artery  pass  to  their 
destination  :  in  front  of  the-  muscle,  the  buccal  branch  of  the  in- 
ferior maxillary  nerve  descends  to  the  buccinator  with  its  companion 
artery. 

The  temporal  muscle  is  in  relation  on  its  deeper  surface  with 
the  external  pterygoid  and  buccinator  muscles,  the  internal  max- 
illary artery  and  vein,  and  the  deep  temporal  arteries  and  nerves. 

PTERYGO-MAX-  The  zygomatic  arch  having  been  already  divided, 

ILLARY  EEGION.  the  structures  should  be  cleaned  so  as  to  expose 
the  coronoid  process  of  the  jaw,  the  insertion  of  the  temporal  muscle, 
and  the  loose  fat  which  surrounds  it.  Next,  saw  through  the 
coronoid  process  in  a  direction  downwards  and  forwards,  so  as  to 
include  the  insertion  of  the  muscle,  and  reflect  it  upwards  without 
injuring  the  subjacent  vessels  and  nerves. 

To  gain  a  good  view  of  the  muscles,  nerves,  and 
DISSECTION 

vessels  of  the  pterygo-maxillary  region,  a  portion 

of  the  ascending  ramus  of  the  jaw  must  be  removed  with  a  Hey's 
saw,  as  shown  in  the  diagram  on  the  next  page. 

In  this  region  we  have  to  examine  the  two  pterygoid  muscles, 
the  trunk  and  branches  of  the  internal  maxillary  artery,  the 
inferior  maxillary  nerve,  and  the  internal  lateral  ligament  of  the 
lower  jaw.  All  these  structures  are  imbedded  in  loose  soft  fat, 
which  must  be  cautiously  removed  without  injuring  them. 

EXTERNAL  This  muscle  arises  by  two  heads,  one,  the  upper, 

PTERYGOID.  from  the  great  wing  of  the  sphenoid  and  from  the 

ridge  below  it ;  the  lower,  from  the  outer  surface  of  the  external 
pterygoid  plate,  a  few  fibres  taking  origin  from  the  outer  side  of 
the  tuberosities  of  the  palate  and  superior  maxillary  bones.  The 
muscle  passes  horizontally  backwards  and  is  inserted  into  the  neck 
of  the  jaw,  and  slightly  into  the  border  of  the  inter-articular  fibre— 
cartilage  of  the  temporo-maxillary  articulation. 

The  advantage  of  the  insertion  of  some  of  its  fibres  into  the 
inter-articular  cartilage  is,  that  the  cartilage  follows  the  condyle  in 
all  its  movements.  When  the  jaw  is  dislocated,  it  is  chiefly  by  the 

K  2 


132 


PTERYGOID   MUSCLES. 


action  of  this  muscle,  which  draws  the  condyle  forwards  into  the 
zygomatic  fossa ;  the  inter-articular  cartilage  being  dislocated  with 
the  condyle. 

By  its  deep  surface  the  muscle  is  in  relation  with  the  internal 
pterygoid  m.,  the  internal  lateral  ligament,  the  arteria  meningea 
media,  the  auriculo-temporal,  the  gustatory,  the  inferior  dental, 
and  chorda  tympani  nerves,  and  occasionally  with  the  internal 


FIG.  33. 


Anterior  deep  temporal  n.  and  a. 


External  pterygoid  m. 

Posterior  deep  temporal  n.  and  a. 
Masscteric  11.  and  a. 


Infra-orbital  a. 
Spheno-maxillary 
fossa     .... 

Superior  dental  a. 
Buccal  a.      .    .    . 

Parotid  duct     .    . 
Buccal  n. .    .    .    . 

Pterygo-maxillary 
ligament. 


Inter-articular 
flbro- cartilage. 

Temporal  artery 
and  auriculo- 
temporal  nerve. 


Middle  meningeal  a. 

Inferior  dental  a. 
Inferior  dental  n. 
Gustatory  n. 
Mylo-hyoid  n. 
Internal  pterygoid  in. 


PTERYGOID    MUSCLES   AND    INTERNAL    MAXILLARY    ARTERY. 

maxillary  artery.  Between  its  two  heads  of  origin  the  buccal  and 
anterior  deep  temporal  nerves  emerge. 

INTERNAL  This  muscle  arises  by  musculo-tendinous  fibres 

PTERYGOID.  from  the  inner  surface  of  the  external  pterygoid 

plate  of  the  sphenoid  bone  and  from  that  portion  of  the  tuberosity 
of  the  palate  bone  which  forms  the  lower  part  of  the  pterygoid 
fossa,  also  by  a  smaller  slip  in  front  of  the  external  pterygoid  from 
the  external  surface  of  the  tuberosities  of  the  palate  and  superior 


INTERNAL  MAXILLARY  ARTERY.  133 

maxillary  bones.    It  is  inserted  into  the  rough  surface  on  the  inner 
side  of  the  angle  of  the  lower  jaw,  as  high  as  the  dental  foramen. 

The  internal  pterygoid  is  in  relation  superficially  with  the  ex- 
ternal pterygoid,  the  internal  lateral  ligament,  the  internal  maxillary 
artery  and  vein,  the  inferior  dental  vessels  and  nerve,  the  mylo-hyoid 
artery  and  nerve,  the  chorda  tympani  and  the  buccal  nerves ;  by  its 
deep  surface,  with  the  tensor  palati  and  superior  constrictor  muscles. 

Notice  particularly  the  direction  of  the  fibres  of  the  pterygoid 
muscles.  The  fibres  of  the  external  run  horizontally  outwards 
and  backwards  from  their  origin ;  the  fibres  of  the  internal  run 
downwards,  backwards  and  outwards  from  their  origin.  The  in- 
ternal pterygoid  has  tendinous  septa  like  the  masseter.  Both  the 
pterygoids  get  their  nerves  from  the  motor  division  of  the  inferior 
maxillary  nerve. 

The  internal  pterygoid  raises  the  lower  jaw,  acting  in  concert 
with  the  temporal  and  masseter  muscles  ;  it  moreover  assists  the 
external  pterygoid  and  anterior  part  of  the  masseter  to  draw  the 
jaw  forwards.  The  external  pterygoid  draws  the  jaw  forwards  and 
somewhat  to  the  opposite  side,  and  also  in  conjunction  with  the 
internal  pterygoid  produces  the  lateral  movements  of  the  jaw 
essential  to  the  mastication  of  the  food.  Consequently  they  are 
enormously  developed  in  all  ruminants  and  comparatively  feebly 
in  carnivorous  animals.  The  antagonistic  muscles  of  the  forward 
action  of  the  two  pterygoids  are  the  temporal  m.  and  the  deep 
fibres  of  the  masseter. 

Saw  through  the  neck  of  the  jaw,  disarticulate 
the  condyle  with  its  fibro-cartilage  from  the 
glenoid  cavity,  and  turn  it  forwards  with  the  external  pterygoid, 
so  that  the  condyle  can  be  replaced  if  desirable.  A  little  dissec- 
tion will  bring  into  view  the  internal  lateral  ligament,  the  internal 
maxillary  artery  and  vein,  the  inferior  maxillary  nerve  and  its 
branches,  and  the  chorda  tympani  nerve. 

INTERNAL  MAX-  This  is  the  larger  of  the  two  terminal  branches 
ILLAEY  AKTERY.  into  which  the  external  carotid  divides,  opposite 
the  neck  of  the  jaw  in  the  parotid  gland.  It  passes  horizontally 
forwards  between  the  neck  of  the  jaw  and  the  internal  lateral  liga- 
ment, then  runs  tortuously,  in  some  cases  above,  in  others  beneath, 


134 


INTERNAL   MAXILLARY    ARTERY. 


the  external  pterygoid,  enters  the  spheno-maxillary  fossa  between 
the  two  heads  of  the  external  pteiygoid,  where  it  terminates  by 
dividing  into  numerous  branches. 

The  course  of  this  artery  is  divided  into  three  stages.  In  the 
first,  the  artery  lies  between  the  neck  of  the  jaw  and  the  internal 
lateral  ligament ;  in  the  second,  it  lies  either  over  or  under  the 
external  pterygoid ;  in  the  third,  it  lies  in  the  spheno-maxillary 
fossa. 


BEANCHES   OF   THE   INTEENAL   MAXILLAEY   AETEEY   IN   THE 
THEEE    STAGES   OF   ITS   COUESE. 


BEANCHES  IN  THE  FIRST     BRANCHES  IN  THE  SECOND 
STAGE.  STAGE. 


BRANCHES  IN  THE  THIRD 
STAGE. 


a.  Tympanic. 


Six  to  the  five   muscles   of     i.  Superior  dental. 


6.  Meningea  media.        mastication,  namely  : 


c.  Meningea  parva. 

d.  Inferior  dental. 


e.  Masseteric. 

/.  Anterior   and  posterior 

deep  temporal. 
g.  External   and    internal 

pterygoid. 
h.  Buccal. 


j.  Infra-orbital. 
k.  Descending  palatine. 
I.  Vidian. 

m.  Pterygo-palatine. 
n.  Nasal    or    spheno-pala- 
tine. 


BRANCHES  IN  a.  The  tympanic  ascends  behind  the  articulation  of 

THE  FIRST  PART.  the  jaw,  and  passes  through  the  Glaserian  fissure  to 
the  tympanum.  It  supplies  that  cavity  and  the  membrana  tympani, 
and  anastomoses  with  the  stylo-mastoid  and  Vidian  arteries.  It  occa- 
sionally gives  off  a  deep  auricular  branch  which  pierces  the  anterior 
wall  of  the  external  auditory  meatus,  supplying  the  skin  of  this  canal. 
This  artery  is  not  infrequently  given  off  from  a  branch  of  the  internal 
maxillary  artery. 

6.  The  middle  meningeal  artery  ascends  between  the  two  roots  of 
the  auriculo-temporal  nerve,  behind  the  external  pterygoid,  and  enters 
through  the  foramen  spinosum  into  the  cranium,  where  it  ramifies 
between  the  dura  mater  and  the  bones.  In  the  skull  it  gives  off  small 
branches  to  the  Gasserian  ganglion  ;  a  petrosal  branch  passing  through 
the  hiatus  Fallppii ;  orbital  branches  entering  the  orbit  through  the 
sphenoidal  fissure  ;  and  temporal  branches  which  pierce  the  great  wing 
of  the  sphenoid  to  enter  the  temporal  fossa.  Its  further  course  is 
described  at  p.  16. 


INTERNAL  MAXILLARY  ARTERY. 


135 


c.  The  meningea,  parva  (not  marked  in  the  plan)  ascends  through 
the  foramen  ovale  into  the  skull,  and  supplies  chiefly  the  ganglion  of 
the  fifth  cranial  nerve.     It  often  comes  from  the  meningea  media. 

d.  The  inferior  dental  artery  descends  behind  the  neck  of  the  jaw 
to  the  dental  foramen,  which  it  enters  with  the  dental  nerve.     It  then 
proceeds  through  a  canal  in  the  diploe  to  the  symphysis,  where  it 
minutely  inosculates  with  its  fellow.    In  this  canal,  which  runs  beneath 
the  roots  of  all  the  teeth,  the  artery  gives  branches  which,  ascend  through 
the  little  foramina  in  the  fangs,  and  supply  the  pulp  in  their  interior. 
Opposite  the  foramen  mentale  arises  the  mental  branch  already  de- 
scribed (p.  49).     Before  entering  the  dental  foramen  the  artery  furnishes 
a  small  branch — mylo-hyoid — which  accompanies  the  nerve  proceeding 
to  the  mylo-hyoid  muscle. 

FIG.  34. 


Tliird  stage.  Second  stage.  First  stage. 

PLAN  OF  INTERNAL  MAXILLARY  ARTERY. 

BRANCHES  IN  e.  The  masseteric  branch  passes  through  the  sigmoid 

THE  SECOND  PART,  notch  of  the  jaw  behind  the  temporal  muscle  to  the 
under  surface  of  the  masseter,  with  the  masseteric  nerve,  and  inoscu- 
lates with  the  facial  and  transverse  facial  arteries. 

f.  The  anterior  and  posterior  deep  temporal  arteries  ascend  to  supply 
the  temporal  muscle,  ramifying  between  the  muscle  and  the  bone,  one 
near  the  front,  the  other  near  the  posterior  border  of  the  muscle.  They 
communicate  with  the  superficial  and  middle  temporal  arteries,  with 
the  terminal  branches  of  the  lachrymal  a.,  and  with  the  temporal 
branches  of  the  arteria  meningea  media. 


136  BRANCHES   OF   THE   INTERNAL  MAXILLARY   ARTERY. 

g.  The  pteryyoid  branches  supply  the  internal  and  external  pterygoid 
muscles. 

h.  The  buccal  branch  runs  forward  with  the  buccal  nerve  to  the 
buccinator,  where  it  anastomoses  with  the  facial  artery. 

BRANCHES  IN  i.  The  superior  dental  branch  runs  along  the  tube- 

THK  THIRD  PABT.  rosity  of  the  superior  maxillary  bone,  and  sends  small 
arteries  through  the  foramina  in  the  bone  to  the  pulps  of  the  molar  and 
bicuspid  teeth.  It  also  supplies  the  gums,  and  the  mucous  membrane 
of  the  antrum. 

j.  The  infra-orbital  branch  ascends  through  the  spheno-maxillary 
fissure,  then  runs  forward  along  the  infra- orbital  canal  with  the  superior 
maxillary  nerve,  and  emerges  upon  the  face  at  the  infra-orbital  foramen, 
beneath  the  levator  labii  superioris.  In  the  infra-orbital  canal  the 
artery  sends  branches,  anterior  dental,  downwards  through  little  canals 
in  the  bone  to  the  incisor  and  canine  teeth,  and  upwards  into  the  orbit 
to  the  lachrymal  gland,  the  inferior  oblique,  and  inferior  rectus.  After 
issuing  from  the  foramen  it  sends  upwards  branches  to  the  lachrymal 
sac,  and  descending  branches  to  the  upper  lip.  The  former  anastomose 
with  the  nasal  branches  of  the  ophthalmic  and  facial  arteries  ;  the 
latter  with  the  superior  coronary,  transverse  facial,  and  buccal  arteries. 

k.  The  descending  palatine,  a  branch  of  considerable  size,  runs  down 
the  posterior  palatine  canal  with  the  palatine  nerve  (a  branch  from 
Meckel's  ganglion),  and  then  along  the  roof  of  the  hard  palate,  towards, 
the  anterior  palatine  canal,  in  which,  much  diminished  in  size,  it  inos- 
culates on  the  septum  nasi  with  a  branch  of  the  spheno-palatine  artery. 
It  supplies  the  gums,  the  glands,  and  mucous  membrane  of  this  part, 
and  furnishes  branches  to  the  soft  palate. 

I.  The  Vidian,  an  insignificant  branch,  runs  backwards  through  the 
Vidian  canal  with  the  Vidian  nerve,  and  is  distributed  to  the  Eustachian 
tube,  the  pharynx,  and  the  tympanum. 

m.  The  ptery go -palatine  is  a  small  but  constant  branch  which  runs 
backwards  through  the  pterygo-palatine  canal  with  the  pharyngeal 
nerve  from  Meckel's  ganglion,  and  ramifies  upon  the  upper  part  of  the 
pharynx  and  the  Eustachian  tube. 

n.  The  nasal  or  splieno-palatine  branch  enters  the  nose  through  the 
spheno-palatine  foramen  in.  company  with  the  nasal  nerve  from  Meckel's 
(spheno-palatine)  ganglion,  and  ramifies  upon  the  spongy  bones,  the 
ethmoidal  cells,  and  the  antrum.  One  large  branch,  the  artery  of  the 
septum,  runs  along  the  septum  nasi  towards  the  anterior  palatine  canal, 
where  it  joins  the  descending  palatine  artery. 


INFERIOR   MAXILLARY   NERVE.  137 

Observe  that  all  the  branches  of  the  internal  maxillary  artery 
in  the  first  and  third  parts  of  its  course  traverse  bony  canals ;  while 
the  branches  in  the  second  part  go  directly  to  muscles. 

The  internal  maxillary  vein  is  formed  by  the  veins  correspond- 
ing to  the  branches  of  the  artery.  As  the  vein  lies  between  the 

PTERYGOID  temporal  and  external  pterygoid  muscles  it  forms 

PLEXUS  OF  VEINS.  a  plexus — ptenjcfoid  plexus — which  communicates, 
above,  with  the  cavernous  sinus  by  branches  which  come  through 
the  foramina  at  the  base  of  the  skull ;  in  front  it  communicates 
with  the  facial  vein.  It  joins  the  temporal  in  the  substance  of  the 
parotid  gland,  and  thus  communicates  with  the  external  jugular 
vein. 

INFERIOR  MAX-  This  great  nerve  is  the   largest  of  the   three 

ILLARY  NERVE  divisions  of  the  fifth  cerebral  nerve.      It  differs 

AND  BRANCHES.  from  the  other  two  divisions,  i.e.  the  ophthalmic 
and  the  superior  maxillary,  in  that  it  contains  motor  as  well  as 
sensory  filaments ;  the  motor  being  furnished  by  the  small  non- 
ganglionic  root  of  the  fifth  nerve.  It  is  necessary  to  remember 
this  point  of  its  physiology,  in  order  to  understand  its  extensive 
distribution ;  for  the  sensory  portion  supplies  the  parts  to  which 
it  is  distributed  with  common  sensation  only,  whilst  the  motor 
portion  supplies  all  the  muscles  concerned  in  mastication. 

The  nerve,  composed  of  sensory  and  motor  filaments,  emerges 
from  the  skull  through  the  foramen  ovale  as  a  thick  trunk,  under 
the  name  of  the  inferior  maxillary.  It  lies  directly  external  to  the 
Eustachian  tube,  and  is  covered  by  the  external  pterygoid  muscle, 
which  must  be  turned  on  one  side  to  expose  it.  Immediately 
after  its  exit  from  the  skull,  the  nerve  divides  into  two  parts,  an 
anterior,  or  motor  division,  and  a  posterior  or  sensory  division. 
From  the  anterior  portion  (chiefly  motor)  are  derived  branches 
distributed  to  the  muscles  of  mastication  and  the  buccal  nerve. 
From  the  posterior  (mainly  sensory)  come  the  following  branches : 
the  auriculo-temporal,  gustatory,  and  inferior  dental ;  there  are 
also  motor  branches  to  the  mylo-hyoid  and  anterior  belly  of  the 
digastricus.  This  apparent  anomaly  will  be  presently  explained. 


138  INFERIOR    MAXILLARY   NERVE. 


BRANCHES   OF   THE   INFEKIOR   MAXILLAEY   NERVE. 

ANTERIOR  PORTION.  POSTERIOR  PORTION. 

Auriculo-temporal.  To  temporal  muscle. 

Inferior  dental.  —  masseter. 

Gustatory  or  lingual.  —  external  pterygoid. 
Mylo-hyoideus.  -  internal  pterygoid. 

Anterior  belly  of  digastricus.  —  buecal. 

The  deep  temporal  branches,  two  in  number,  anterior  and  pos- 
terior, pass  outwards  close  to  the  great  wing  of  the  sphenoid  bone, 
and  ascend  with  the  temporal  arteries  to  the  temporal  muscle.  A 
middle  temporal  nerve  is  not  infrequently  present,  and  ascends 
beneath  the  temporal  muscle  to  enter  its  deeper  aspect.  The 
posterior  branch  is  occasionally  joined  with  the  masseteric  nerve, 
the  anterior  with  the  buecal  nerve. 

The  branch  to  the  masseter  runs  outwards  above  the  external 
pterygoid,  through  the  sigmoid  notch  of  the  jaw,  to  the  under 
surface  of  the  muscle. 

The  branch  to  the  external  pterygoid  comes,  apparently,  from 
the  buecal  nerve  in  its  passage  through  this  muscle. 

The  branch  to  the  internal  pterygoid  muscle  proceeds  from  the 
inner  side  of  the  main  trunk,  close  to  the  otic  ganglion,  and 
descending  between  the  internal  pterygoid  and  the  tensor  palati, 
enters  the  inner  and  deeper  aspect  of  the  muscle. 

The  buecal  branch,  a  sensory  nerve,  united  at  its  origin  with 
the  anterior  deep  temporal  and  external  pterygoid  nerves,  passes 
either  above  or  between  the  fibres  of  the  external  pterygoid  to  the 
buccinator,  where  it  spreads  out  into  filaments,  which  form  a 
plexus  with  the  buecal  branches  of  the  facial  nerve,  and  then  supply 
the  skin,  mucous  membrane,  and  glands  of  the  cheek  with  common 
sensation.  The  motor  power  of  the  buccinator,  remember,  is  de- 
rived from  the  facial  nerve.  That  this  buecal  branch  is  mainly 
sensory  is  proved  by  the  action  of  the  muscle  still  continuing  when 
the  motor  division  of  the  fifth  nerve  is  paralysed.  The  evidence  is 
corroborated  by  a  case  in  which  this  buecal  branch  proceeded  from 
the  second  division  of  the  fifth  nerve;  no  communication  being 


INFERIOR   MAXILLARY   NERVE. 


139 


discovered,  after  very  careful  dissection,  between  it  and  the  motor 
root  of  the  third  division.1 

The  auricula-temporal  branch  arises  by  two  roots  which  embrace 
the  middle  meningeal  artery  before  it  enters  the  skull.  The  nerve 
runs  backwards  behind  the  external  pterygoid  and  the  neck  of  the 
jaw,  ascends  at  first  beneath  the  parotid  gland,  then  over  the  root 
of  the  zygoma  with  the  temporal  artery,  and  divides,  like  it,  into 

FIG.  35. 


PLAN    OF    THE    BRANCHES    OF    THE    INFERIOR    MAXILLARY    NERVE. 

an  anterior  and  a  posterior  branch.  The  posterior  branch  supplies 
the  pinna  and  surrounding  tissues  ;  the  anterior  is  distributed  to 
the  skin  covering  the  vertex  and  temporal  region,  communicating 
with  the  temporal  branches  of  the  facial  nerve  and  the  orbital 
branch  of  the  superior  maxillary. 

1  Turner,  '  On  the  Variation  of  the  Buccal  Nerve.'    Journal  of  Anat.  and  Phys., 
Ko.  I.,  1866. 


140  INFERIOR   MAXILLARY   NERVE. 

The  auriculo-temporal  communicates  at  its  origin  with  the  otic 
ganglion,  and  then  ascends  behind  the  jaw  with  the  temporal 
branches  of  the  facial  n. ;  it  also  gives  off  an  articular  branch  to 
the  temporo-maxillary  joint ;  ttvo  branches  to  the  meatus  auditorius 
and  the  membrana  tympani ;  parotid  branches  to  the  gland ;  auri- 
cular branches,  two  in  number — an  inferior,  which  is  distributed 
to  the  ear  below  the  auditory  meatus,  and  a  superior  to  the  tragus 
and  auricle.  Its  branches  have  been  described  (p.  6). 

The  inferior  dental  branch  emerges  beneath  the  external  ptery- 
goid,  and  descends  between  the  ramus  and  the  internal  lateral 
ligament  of  the  jaw  to  the  dental  foramen,  which  it  enters  with 
the  dental  artery.  It  then  runs  in  the  canal  in  the  diploe  of  the 
jaw  and  furnishes  filaments  which  ascend  through  the  canals  in 
the  fangs  of  the  teeth  to  the  pulp  in  their  interior.  Opposite  the 
foramen  mentale  it  divides  into  two  branches,  the  mental  and 
incisor.  Observe  that  the  same  nerve  which  supplies  the  teeth 
supplies  the  gums  ;  hence  the  sympathy  between  them. 

a.  The  mylo-hyoid  branch,  apparently  arising  from  the  dental,  is 
derived  from  the  motor  root  of  the  fifth,  and  may,  with  careful  dissec- 
tion, be  traced  to  it.     It  leaves  the  sheath  of  the  inferior  dental  nerve 
near  the  foramen  in  the  jaw,  and  runs  in  a  groove  on  the  inner  side  of 
the  ramus  to  the  lower  surface  of   the  mylo-hyoid,  which  muscle  it 
supplies  together  with  the  anterior  portion  of  the  digastricus. 

b.  The  dental  branches  pass  upwards  to  the  fangs  of  the  molar  and 
bicuspid  teeth. 

c.  The  incisor  branch  is  the  continuation  of  the  nerve,  and  passes  to 
the  symphysis,  supplying  the  canine  and  incisor  teeth. 

d.  The  mental  branch  (sometimes  called    labial)  emerges  through 
the  foramen  mentale,  and  soon  divides  into  numerous  branches ;  some 
ascend  to  the  lower  lip  beneath  the  depressor  labii  inferioris,  and  com- 
municate with  the  facial  nerve ;    others  pass  inwards  to  the  skin  of 
the  chin. 

The  giistatory  or  lingual  nerve  lies  at  first  behind  the  external 
pterygoid  m.,  then  descends  obliquely  forwards  between  the  ramus 
of  the  jaw  and  the  internal  pterygoid  in.,  and  subsequently  for  a 
short  distance  between  the  jaw  and  the  superior  constrictor  of  the 
pharynx.  Here  it  lies  close  under  the  mucous  membrane  of  the 


GUSTATORY   NERVE.  141 

mouth  near  the  last  molar  tooth  of  the  lower  jaw.  Division  of 
it  in  this  situation  relieves  pain  in  cancer  of  the  tongue.  The  gus- 
tatory n.  then  rests  upon  the  stylo-glossus  and  the  hyo-glossus  m., 
and  after  crossing  Wharton's  duct  passes  to  the  tip  of  the  tongue. 

The  nerve  at  first  lies  in  front  of  the  inferior  dental  nerve 
(with  which  it  is  frequently  connected),  and  beneath  the  internal 
maxillary  a.  Beneath  the  external  pterygoid,  the  gustatory  n.  is 
joined  at  an  acute  angle  by  the  chorda  tympani  (a  branch  of  the 
facial).  This  branch  emerges  through  a  small  canal,  canal  of 
Huguier,  by  the  side  of  the  Glaserian  fissure,  and  passing  behind 
the  dental  n.,  meets  the  gustatory,  and  runs  along  the  lower  border 
of  this  nerve  to  supply  the  submaxillary  gland  ;  part  of  it  joins 
the  submaxillary  ganglion,  and  it  is  then  eventually  distributed  to 
the  lingualis  muscle. 

The  gustatory  nerve  in  its  course  gives  off — 

a.  Communicating  branches  to  the  hypoglossal  n.,  forming  two  or 
more  loops  at  the  anterior  border  of  the  hyo-glossus  muscle. 

b.  Communicating  branches  to  the  submaxillary  ganglion. 

c.  Branches  to  the  mucotis  membrane  of  the  mouth,  gums,  and  sub- 
lingual  gland. 

d.  Lingual  branches  which  pass  to  the  papillae  of  the  sides  and  tip 
of  the  tongue  :  here  also  we  find  communications  between  this  nerve 
and  the  hypoglossal. 

The  duct  of  the  submaxillary  gland  (p.  94),  Wharton's  duct,  can 
now  be  traced  to  its  termination.  It  passes  from  its  under  surface, 
runs  forwards  under  the  mylo-hyoideus  and  upon  the  hyo-glossus 
muscle  ;  it  then  passes  beneath  the  gustatory  nerve,  and  subse- 
quently runs  between  the  sublingual  gland  and  the  genio-hyo- 
glossus,  to  open  into  the  floor  of  the  mouth,  by  the  side  of  the 
frasimm  linguae.  Its  length  is  about  two  inches  ;  its  dimensions  are 
not  equal  throughout ;  it  is  dilated  about  the  middle,  and  contracted 
at  the  orifice.  Saliva,  collected  in  the  dilated  portion,  is  sometimes 
spirted  to  a  considerable  distance  out  of  the  narrow  orifice,  in  con- 
sequence of  the  sudden  contraction  of  the  neighbouring  muscles. 

The  gland  is  supplied  with  nerves  by  branches  from  the  sub- 
maxillary ganglion,  from  the  sympathetic,  and  the  mylo-hyoid 
nerves. 


142  DTTERXAL   LATERAL   LIGAMENT. 

In  the  floor  of  the  mouth  there  occasionally  exists  a  cystic 
tumour,  called  a  ra?i«Z«,  with  semi-transparent  walls,  perceptible 
beneath  the  tongue.  By  some  of  the  older  writers  it  was  looked 
upon  as  an  abnormal  dilatation  of  the  submaxillary  duct.  There 
is,  however,  no  reason  for  believing  this  swelling  (except  very 
rarely)  to  be  connected  with  the  duct.  It  is  rather  a  cyst  formed 
in  the  loose  areolar  tissue  under  the  tongue,  or  is  an  enlargement 
of  one  of  the  small  bursae  which  normally  exist  in  this  situation. 
The  character  of  the  saliva  presents  no  agreement  with  the  fluid 
contained  in  these  cysts,  which  is  thickly  glairy,  like  the  white  of 
an  egg. 

This  so-called  ligament  (which  is  more  like  a 
LATEBAL  LIGAMENT  layer  of  fascia)  passes  from  the  spinous  process 
oFTHELowEE  of  the  sphenoid  bone  to  the  inner  side  of  the 
'AW>  foramen  dentale.  Between  this  ligament  and  the 

neck  of  the  jaw,  we  find  the  internal  maxillary  artery  and  vein, 
the  auriculo-temporal  nerve,  the  middle  meningeal  artery,  the 
inferior  dental  nerve  and  artery,  and  a  portion  of  the  parotid 
gland. 

At  this  stage  of  the  dissection  you  will  be  able  to  trace  the 
course  and  relations  of  the  internal  carotid  artery.  But  before 
doing  this,  examine  the  several  objects  which  intervene  between 
the  external  and  internal  carotids.  These  are — 1.  The  stylo- 
glossus ;  2.  The  stylo-pharyngeus ;  3.  The  glosso-pharyngeal  nerve; 
4.  The  stylo-hyoid  ligament. 

This  arises  from  the  front  of  the  styloid  process 
STTLO-GLOSSCS.  ,  ,  -          .1,1  m          T 

near  the  apex,  and  from  the  stylo-maxillary  liga- 
ment. It  passes  at  first  downwards  and  then  horizontally  forwards, 
and  is  inserted  along  the  side  of  the  tongue  as  far  as  the  tip,  some 
of  its  lower  fibres  decussating  with  those  of  the  hyo-glossus.  Its 
action  is  to  retract  the  tongue.  Its  nerve  is  a  branch  of  the  hypo- 
glossal. 

STYLO-  This  arises  from  the  inner  side  of  the  styloid 

PHABYXGECS.  process   near  the  base,  and   is   inserted  into  the 

upper  and  posterior  edges  of  the  thyroid  cartilage.  It  descends 
along  the  side  of  the  pharynx  between  the  superior  and  the  middle 
constrictors ;  some  of  its  fibres  blend  with  the  constrictor  muscles ; 


GLOSSO-PHARYNGEAL   NERVE.  143 

others  join  those  of  the  palato-pharyngeus  at  its  insertion.  Curving 
round  its  lower  border  is  seen  the  glosso-pharyngeal  nerve,  from 
which  its  nerve-supply  is  derived.  Its  action  is  to  raise  the  larynx 
with  the  pharynx  in  deglutition.1 

Between  the  stylo-glossus  and  stylo-pharyngeus,  and  nearly 
parallel  with  both,  is  the  stylo-ht/oid  ligament.  It  extends  from 
the  apex  of  the  styloid  process  to  the  lesser  cornu  of  the  os  hyoides. 
It  is  often  more  or  less  ossified. 

The  ascending  palatine  artery,  a  branch  of  the  facial  (p.  98), 
runs  up  between  the  stylo-glossus  and  the  stylo-pharyngeus,  and 
divides  into  branches  which  supply  these  muscles,  the  palate,  the 
side  of  the  pharynx,  and  the  tonsils.  It  inosculates  with  the 
descending  palatine,  a  branch  of  the  internal  maxillary. 

GLOSSO-PHA-  The  glosso-pharyngeal  nerve  is  observed  curving 

BYNGEAL  NEEVE.  forwards  round  the  lower  border  of  the  stylo- 
pharyngeus  (p.  142).  It  is  the  ninth  cranial  nerve,  arises  by  five 
or  six  filaments  from  the  groove  between  the  olivary  body  and  the 
restiform  tract  of  the  medulla  oblongata,  leaves  the  skull  through 
the  middle  part  of  the  foramen  jugulare  in  a  separate  sheath  of 
dura  mater,  in  front  of  the  pneumogastric  and  spinal  accessory 
nerves,  and  descends  between  the  internal  jugular  vein  and  the  in- 
ternal carotid  artery.  It  then  crosses  in  front  of  the  artery  below 
the  styloid  process,  and  proceeds  along  the  lower  border  of  the 
stylo-pharyngeus.  At  this  point,  it  curves  forwards  over  that 
muscle  and  the  middle  constrictor  of  the  pharynx,  and  disappears 
beneath  the  hyo-glossus,  where  it  divides  into  its  terminal  branches, 
which  supply  the  mucous  membrane  of  the  pharynx,  the  back  of 
the  tongue,  and  the  tonsils. 

The  glosso-pharyngeal  is,  at  its  origin,  purely  a  sensory  nerve. 
But  soon  after  its  exit  from  the  skull  it  receives  communications 
from  the  facial,  the  pneumogastric,  and  the  sympathetic,  so  that  it 
soon  becomes  a  compound  nerve — i.e.  composed  of  both  sensory 
and  motor  filaments.  At  the  base  of  the  skull  it  presents  two 

1  Varieties  of  this  muscle  are  frequently  met  with,  chiefly  as  supernumerary 
muscles.  They  arise  variably  from  neighbouring  parts  of  the  base  of  the  skull 
close  to  the  styloid  process,  and  are  inserted  either  into  the  pharyngeal  constrictors 
or  into  the  aponeurosis  of  the  pharynx. 


144  INTERNAL  CAROTID  ARTERY. 

ganglia — tine  jugular  and  the  petrous  (ganglion  of  Andersch).  The 
branches  given  off  by  the  petrous  ganglion  will  be  dissected  here- 
after ;  at  present  the  student  can  only  make  out  the  branches  which 
this  nerve  gives  off  in  the  neck,  namely : — 

Carotid  branches,  which  surround  the  internal  carotid  artery  as 
far  as  its  origin,  and  communicate  with  the  pharyngeal  branch  of  the 
pneumogastric  and  with  the  sympathetic. 

Pharnygeal  branches,  three  or  four  in  number,  which  form  by  the 
side  of  the  middle  constrictor  of  the  pharynx,  a  plexus,  the  pharyngeal 
plexus,  supplemented  by  filaments  derived  from  the  pneumogastric,  the 
nervus  accessorius,  the  external  laryngeal,  and  the  sympathetic.  Its 
branches  supply  the  constrictor  muscles  and  the  mucous  membrane  of 
the  pharynx,  the  back  of  the  tongue,  and  the  tonsils. 

Muscular  branches  which  enter  the  stylo-pharyngeus  m. 

Tonsillar  branches  which  are  given  to  the  soft  palate  and  the  fauces, 
and  to  the  tonsils  forming  a  plexus  (circulus  tonsillaris). 

Lingual  brandies,  two  in  number,  which  are  distributed  to  the  base 
and  lateral  aspects  of  the  tongue  :  one  branch  turns  upwards  and  is 
distributed  to  the  papillae  circumvallatse,  and  the  mucous  membrane  of 
the  posterior  third  of  the  tongue  as  far  backwards  as  the  epiglottis  ;  the 
other  passes  to  the  middle  of  the  side  of  the  tongue  communicating  with 
the  gustatory  nerve. 

The  styloid  process  must  now  be  cut  through  at  its  base,  and 
turned  forwards  with  the  muscles  arising  from  it.  The  internal 
carotid  artery  will  thus  be  exposed  in  the  cerviqal  region,  as  far 
as  the  carotid  canal.  The  part  of  the  artery  contained  within  the 
carotid  canal  will  be  described  hereafter. 

INTERNAL  The  internal  carotid  artery  proceeds  from  the 

CAKOTID  ABTEET.  bifurcation  of  the  common  carotid  at  the  upper 
border  of  the  thyroid  cartilage,  and  ascends  vertically  to  the  base 
of  the  skull  by  the  side  of  the  pharynx,  in  front  of  the  transverse 
processes  of  the  three  upper  cervical  vertebrae.  It  enters  the  skull 
through  the  carotid  canal  in  the  temporal  bone,  runs  tortuously 
by  the  side  of  the  body  of  the  sphenoid,  and  terminates  in  branches 
which  supply  the  orbit  and  the  brain.  It  is  divided  into  four  por- 
tions— the  cervical,  petrous,  cavernous,  and  cerebral.  In  the  cer- 
vical part  of  its  course,  it  is  situated  immediately  to  the  outer  side 


INTERNAL  CAROTID  ARTERY.  145 

of  the  external  carotid  artery,  behind  the  inner  border  of  the  sterno- 
mastoid.  It  soon  gets  beneath  the  external  carotid,  and  lies  deeply 
beneath  the  parotid  gland,  and  ascends  by  the  side  of  the  pharynx 
and  tonsil.  It  lies  upon  the  rectus  capitis  anticus  major,  the  supe- 
rior laryngeal  nerve,  and  the  superior  cervical  ganglion  of  the  sym- 
pathetic ;  to  its  outer  side,  is  the  internal  jugular  vein  and  the 
pneumogastric  nerve  ;  to  its  inner  side,  is  the  pharynx,  the  tonsil, 
and  the  ascending  pharyngeal  artery  ;  it  is  crossed,  successively,  by 
the  hypoglossal  nerve,  the  occipital  artery,  the  digastricus,  and 
stylo-hyoid  muscles  ;  higher  up  it  is  crossed  by  the  styloid  process, 
the  stylo-glossus,  and  stylo-pharyngeus  muscles,  by  the  glosso- 
pharyngeal  nerve  and  the  stylo-hyoid  ligament,  all  of  which  last- 
named  structures  intervene  between  it  and  the  external  carotid. 

The  most  important  relation  of  the  artery,  in  a  surgical  point 
of  view,  is,  that  it  ascends  close  by  the  s.ide  of  the  pharynx  and 
tonsil.  In  opening  an  abscess,  therefore,  near  the  tonsil,  or  at 
the  back  of  the  pharynx,  be  careful  to  introduce  the  knife  with 
its  point  inwards  towards  the  mesial  line :  observe  this  caution 
the  more,  because  in  some  subjects,  the  internal  carotid  makes  a 
curve,  or  even  a  complete  curl  upon  itself,  in  its  ascent  near  the 
pharynx.  In  such  cases  an  undue  deviation  of  the  instrument  in 
an  outward  direction  might  injure  the  vessel. 

ASCENDING  This  artery  generally  arises  from  the  back  part 

PUABYNGEAL  of  the  external  carotid  about  half  an  inch  above 

ABTEEY.  the  angle  of  the  common  carotid.     It  ascends  in  a 

straight  course  between  the  internal  carotid  artery  and  the  side  of 
the  pharynx,  towards  the  base  of  the  skull,  resting  upon  the  rectus 
capitis  anticus  major.  Its  gives  off  three  sets  of  branches  : — 

a.  Pharyngeal  branches,  three  or  four  in  number  :  the  two  lower 
supply  the  inferior  and  middle  constrictors,  and  stylo-pharyngeus,  ana- 
stomosing with  the  superior  thyroid  a.  ;  the  upper  branch,  the  palatine, 
ascends   upon   the   superior   constrictor,   runs  down  with  the  levator 
palati,  above  the  superior  constrictor,  and  supplies  the  muscles  of  the 
palate,  the  Eustachian  tube,  and  the  tonsil. 

b.  Prevertebral  branches,   which  supply  the  prevertebral   muscles, 
the  superior  cervical  ganglion  of  the  sympathetic,  the  lymphatic  glands, 
and  the  pneumogastric  and  hypoglossal  nerves. 

L 


146  PNEUMOGASTRIC   NERVE. 

c.  Meningeal  branches,  which  supply  the  dura  mater  ;  passing 
through  the  foramen  lacerum  medium,  the  anterior  condylar  foramen, 
and  the  foramen  jugulare  with  the  internal  jugular  vein. 

PNEUMOGASTBIC  The  pneumogastric  nerve  is  the  tenth  cranial 
NEKVE.  nerve,  and  has  the  longest  course  of  all  the  cerebral 

nerves.  It  arises  from  the  medulla  oblongata  by  a  series  of  roots, 
from  twelve  to  fifteen  in  number,  from  the  front  of  the  restiform 
body.  It  passes  out  of  the  skull  in  a  common  sheath  of  dura 
mater  and  arachnoid,  with  the  nervus  accessorius  through  the 
foramen  jugulare. 

Within  the  foramen  jugulare  a  small  ganglion — ganglion  of  tlie 
root  (Arnold's  ganglion) — about  two  lines  in  length,  is  situated 
upon  the  pneumogastric  nerve,  and  is  joined  by  a  branch  from  the 
nervus  accessorius.  This  ganglion  will  be  described  hereafter. 
About  half  an  inch  below  the  preceding  the  pneumogastric  nerve 
swells  out,  and  forms  a  second  ganglion — ganglion  of  the  trunk — 
(inferior  ganglion),  of  a  reddish-grey  colour.  This  ganglion  occu- 
pies about  an  inch  of  the  nerve,  but  does  not  involve  the  whole  of 
its  fibres ;  the  branch  from  the  spinal  accessory  joining  the  pneumo- 
gastric below  the  ganglion.  It  is  united  to  the  hypoglossal  nerve, 
from  which  it  receives  filaments  :  it  also  receives  filaments  from 
the  first  and  second  spinal  nerves,  and  from  the  superior  cervical 
ganglion  of  the  sympathetic. 

Thus,  the  pneumogastric,  at  its  origin  probably  a  nerve  of 
sensation  only,  becomes,  in  consequence  of  the  connecting  filaments 
from  these  various  branches,  a  compound  nerve,  and  in  all  respects 
analogous  to  a  spinal  nerve. 

Leaving  the  skull  at  the  foramen  jugulare,  the  nerve  descends 
in  front  of  the  cervical  vertebras,  lying  successively  upon  the  rectus 
capitis  anticus  major  and  the  longus  colli.  In  the  upper  part  of 
the  neck  it  is  situated,  lying  in  the  same  sheath,  between  the  in- 
ternal carotid  artery  and  the  internal  jugular  vein ;  lower  down, 
it  lies  between  and  behind  the  common  carotid  and  the  internal 
jugular  vein.  It  enters  the  chest,  on  the  right  side,  crossing  in 
front  of  the  first  part  of  the  subclavian  artery,  nearly  at  a  right 
angle  ;  on  the  left,  running  nearly  parallel  with  it. 

In  their  course  through  the  chest,  the  pneumogastric  nerves 


PNEUMOGASTRIC   NERVE.  147 

have  not  similar  relations.  The  right  nerve  lies  beneath  the  subcla- 
vian  vein,  and  then  descending  behind  the  right  brachio-cephalic 
vein  by  the  side  of  the  trachea,  is  continued  behind  the  right 
bronchus  to  the  posterior  part  of  the  oesophagus.  The  left  nerve 
passes  behind  the  left  brachio-cephalic  vein,  then  crosses  in  front  of 
the  arch  of  the  aorta,  and  behind  the  left  bronchus  to  the  anterior 
part  of  the  oesophagus.  Both  nerves  subdivide  on  the  oesophagus 
into  a  plexus;  the  right  nerve  forming  the  posterior  ossophageal 
plexus,  the  left  the  anterior.  Each  plexus  again  collects  its  fibres 
together  to  form  a  single  trunk  :  thus  two  main  nerves  are  formed 
which  pass  with  the  oesophagus  through  the  diaphragm :  of  these 
the  right  is  distributed  over  the  posterior,  the  left  over  the  anterior 
surface  of  the  stomach.1 

In  their  long  course  from  the  medulla  oblongata  to  the  abdo- 
men, the  pneumogastric  nerves  supply  branches  to  most  important 
organs :  namely,  to  the  pharynx,  the  larynx,  the  heart,  the  lungs, 
the  oesophagus,  the  stomach,  and  the  liver. 

The  branches  of  the  pneumogastric  are  those  of  communication 
and  those  of  distribution  : — 

1 .  The  branches  of  communication  are  those  in  connection  with 
the  ganglion  of  the  root  and  the  ganglion  of  the  trunk. 

a.  The  ganglion  of  the  root  has  connecting  filaments  with  the 
accessory  portion  of  the  spinal  accessory,  the  superior  cervical 
ganglion  of  the  sympathetic,  and  with  the  petrous  ganglion  of  the 
glosso-pharyngeal. 

I).  The  ganglion  of  the  trunk  has  communicating  filaments  with 
the  hypoglossal,  the  loop  between  the  first  two  cervical  nerves,  and 
the  superior  cervical  ganglion  of  the  sympathetic. 

2.  The  branches  of  distribution  are — 

a.  The  auricular  (Arnold),  which  cannot  at  present  be  seen, 
will  be  made  out  in  the  dissection  of  the  nerve  at  the  base  of  the 
skull. 

b.  The  plianjngeal  arises  from  the  upper  part  of  the  ganglion 
of  the  trunk,  and,  receiving  a  filament  from  the  accessory  part  of 

1  The  differences  in  the  course  and  destination  of  the  right  and  the  left 
pneumogastric  nerves  may  be  explained  in  the  process  of  development.  The 
student  is  therefore  referred  to  works  which  treat  of  this  subject. 

L  2 


148  BRANCHES   OF   THE    PNEUMOGA3TRIC   NERVE. 

the  spinal  accessory,  descends  either  in  front  of,  or  behind  the 
internal  carotid.  The  nerve,  after  passing  to  the  inner  side  of  the 
internal  carotid,  divides  into  branches,  which  with  the  other  fila- 
ments (described  p.  144)  upon  the  middle  constrictor  muscle  form 
the  pharyngeal  plexus.  From  this  plexus  branches  are  distributed 
to  the  muscles  and  the  mucous  membrane  of  the  pharynx.1 

c.  The   superior   larynyeal,    derived   from   the   middle  of  the 
ganglion  of  the  trunk,  descends  behind  the  internal  carotid,  and 
divides  into  two  branches,  the  internal  and  the  external  laryngeal. 

The  internal  laryngeal  passes  to  the  interval  between  the  os  hyoides 
and  the  thyroid  cartilage,  and  enters  the  larynx  (with  tlie  superior 
laryngeal  a.),  through  the  thyro-hyoid  membrane,  to  be  distributed,  as 
a  nerve  of  sensation,  to  the  mucous  membrane  of  the  larynx  and  epi- 
glottis. The  external  laryngeal,  the  smaller,  gives  off  some  branches  to 
the  pharyngeal  plexus,  the  inferior  constrictor,  and  the  thyroid  body, 
and  then  descends  by  the  side  of  the  larynx  beneath  the  depressors  of 
the  os  hyoides  to  supply  the  crico-thyroid  muscle  :  it  communicates 
with  the  superior  cardiac  nerve  of  the  sympathetic. 

d.  The  cervical  cardiac  branches  descend  behind  the  sheath  of 
the  carotid  artery  to  the  cardiac  plexus.     The  upper  brandies,  one 
or  two  in  number,  are  small,  and  proceed  from  the  ganglion  of  the 
trunk ;  they  join  the  cardiac  branches  of  the  sympathetic  and  the 
deep    cardiac   plexus ;    the    lower   conies   from    the  trunk  of  the 
pneumogastric  before  it  enters  the  chest.     Subsequently,  the  right 
lower  cardiac  nerve  descends  by  the  side  of  the  innominate  artery 
to  join  the  deep  cardiac  plexus ;  the  left  passes  over  the  arch  of 
the  aorta  to  join  the  superficial  cardiac  plexus. 

e.  The  inferior-  or  recurrent  laryngeal  nerve  turns,  on  the  right 
side,  under  the  subclavian  artery  (p.  113),  and  ascends  obliquely 
inwards  to  the  larynx  behind  the  common  carotid  and  the  inferior 
thyroid  arteries  :  it  lies  subsequently  in  the  groove  between  the 
oesophagus  and  the  trachea.     On  the  left  side,  it  turns  under  the 
arch  of  the  aorta,  just  on  the  outer  side  of  the  remains  of  the 
ductus  arteriosus ;  after  which  it  runs  up  between  the  trachea  and 

1  A  branch  from  the  plexus  is  described  by  Luschka  as  receiving  filaments 
from  the  pharyngeal  branches  of  the  glosso-pharyngeal  and  pneumogastric  nerves, 
and  joining  with  the  hypoglossal  as  it  winds  round  the  occipital  artery. 


SPINAL   ACCESSORY  NERVE.  149 

the  oesophagus.  On  both  sides  the  nerves  enter  the  larynx  beneath 
the  lower  border  of  the  inferior  constrictor,  and  supply  all  the 
intrinsic  muscles  of  the  larynx,  except  the  crico-thyroid.  These 
nerves  as  they  turn  under  their  respective  vessels  give  off  cardiac 
branches  to  the  deep  cardiac  plexus.  They  supply  also  filaments 
to  the  trachea,  oesophagus,  and  inferior  constrictor  muscle. 

The  remaining  branches  of  the  pneumogastric  nerve  to  the 
lungs,  heart,  oesophagus  and  stomach  will  be  examined  in  the 
dissection  of  the  chest. 

SPINAL  ACCES-  The  spinal  accessory  nerve  issues  through  the 

SORT  NERVE.  middle  part  of  the  foramen  jugulare,  in  a  sheath 

of  dura  mater  common  to  it  and  the  pneumogastric  nerve.  It 
arises  by  numerous  filaments  from  the  side  of  the  medulla  oblon- 
gata  below  the  pneumogastric,  and  from  the  lateral  column  of  the 
spinal  cord  as  low  down  as  the  sixth  cervical  vertebra.  The  fila- 
ments which  arise  from  the  medulla  oblongata  join  to  form  the 
accessory  portion  of  the  nerve ;  the  spinal  filaments  ascend  between 
the  ligamentum  denticulatum  and  the  posterior  roots  of  the  cervical 
spinal  nerves,  and  form  the  spinal  portion  of  the  nerve.  These  por- 
tions converge  to  the  jugular  foramen,  where  they  communicate  with 
each  other  more  or  less,  and  are  then  continued  onwards  below 
the  jugular  foramen  as  two  portions — the  internal  or  accessory, 
which  joins  the  pneumogastric  n. ;  the  external  or  spinal  which  is 
distributed  to  muscles. 

The  accessory,  part,  within  the  foramen  jugulare,  sends  one  or 
more  filaments  to  the  ganglion  of  the  root  of  the  pneumogastric. 
It  lies  close  to  the  pneumogastric  nerve  at  the  ganglion  of  the 
trunk,  and  is  finally  incorporated  with  the  nerve  below  the  ganglion. 
It  sends  filaments  to  the  pharyngeal  and  superior  laryngeal  branches 
of  the  pneumogastric. 

The  spinal  part  separates  from  the  accessory  part  below  the 
foramen  jugulare.  It  then  takes  a  curved  course  backwards  and 
outwards,  lying  in  front  of  the  internal  jugular  vein  and  the  trans- 
verse process  of  the  atlas,  and  behind  the  digastric  and  stylo-hyoid 
muscles.  It  pierces  the  upper  part  of  the  sterno-mastoid  muscle 
accompanied  by  the  superior  sterno-mastoid  artery,  a  branch  of  the 
occipital,  and  supplies  the  muscle,  joining  in  its  substance  with 


150  SYMPATHETIC    NERVE   IN   THE    NECK. 

branches  from  the  third  cervical  n.  The  nerve  then  crosses 
obliquely  the  occipital  triangle,  where  it  communicates  with  the 
second  and  third  cervical  nerves.  It  is  eventually  distributed  to 
the  under  aspect  of  the  trapezius,  where  it  is  joined  by  branches 
from  the  third  and  fourth  cervical  nerves. 

HYPOGLOSSAL  This  nerve  arises,  by  from  ten  to  fifteen  filaments, 

NEEVE.  from  the  groove  between  the  anterior  pyramid  and 

the  olivary  body.  It  passes  through  the  dura  mater  in  two  fasciculi, 
which  emerge  from  the  skull  through  the  anterior  condylar  fora- 
men, and  then  unite  to  form  a  single  nerve.  It  comes  forward 
between  the  internal  jugular  vein  and  the  internal  carotid  artery, 
where  it  is  intimately  connected  with  the  pneumogastric  nerve. 
Its  further  course  has  been  described  (p.  103). 

In  the  anterior  condylar  foramen  the  hypoglossal  gives  off  a 
small  filament  to  the  diploe  and  to  the  dura  mater  around  the  fora- 
men magnum.  At  the  base  of  the  skull  it  gives  off  several  branches, 
which  connect  it  with  the  ganglion  of  the  trunk  of  the  pneumo- 
gastric nerve.  These  two  nerves  are  sometimes  almost  inseparably 
united.  It  gives  off  also  several  delicate  filaments  to  the  superior 
cervical  ganglion  of  the  sympathetic,  and  communicates  with  the 
loop  formed  by  the  first  two  spinal  nerves  in  front  of  the  atlas. 
SYMPATHETIC  Now  examine  the  cervical  ganglia  of  the  sym- 

NEBVE.  pathetic  system  of  nerves.     This  system  consists 

of  a  series  of  ganglia  arranged  on  each  side  of  the  spine,  from  the 
first  cervical  to  the  last  sacral  vertebra.  The  successive  ganglia  of 
the  same  side  are  connected  by  intermediate  nerves,  so  as  to  form 
a  continuous  cord  on  each  side  of  the  spine :  this  constitutes  what 
is  called  the  trunk  of  the  sympathetic  system,  and  is  connected 
with  all  the  spinal  nerves.  Its  upper  or  cephalic  extremity  enters 
the  cranium  through  the  carotid  canal,  surrounds  the  internal 
carotid  artery,  communicates  with  the  third,  fourth,  fifth,  and 
sixth  cranial  nerves,  and  joins  its  fellow  of  the  opposite  side  upon 
the  anterior  communicating  artery.1  Its  sacral  extremity  joins 
its  fellow  by  means  of  the  little  ganglion  impar,  situated  in  the 
mesial  line,  upon  the  coccyx. 

The  ganglia  are  connected  together  by  branches  composed  of 
1  Here  is  situated  the  so-called  ganglion  of  Ribes. 


SYMPATHETIC  NERVE  IN  THE  NECK.  151 

grey  and  white  nerve-fibres  ;  they  are  also  connected  with  the 
spinal  nerves  by  two  filaments — one,  of  white  nerve-fibres  which 
passes  from  the  spinal  nerve  to  the  ganglion ;  the  other,  of  grey, 
from  the  ganglion  to  the  spinal  nerve.  Branches  of  distribution 
are  also  given  off  by  the  ganglia,  some  to  the  various  blood-vessels 
and  viscera,  forming  intricate  plexuses  upon  them  ;  others  to  the 
various  ganglia  of  the  viscera — the  cardiac  and  semilunar  ganglia. 

The  different  portions  of  the  sympathetic  gangliated  cord  re- 
ceive, respectively,  the  distinguishing  names  of  the  cervical,  dorsal, 
lumbar,  sacral,  and  coccygeal.  At  present  we  have  only  to  consider 
the  cervical  portion  of  it. 

To  expose  the  cervical  ganglion  of  the  sympathetic,  the  internal 
carotid  artery,  the  pneumogastric,  glosso-pharyngeal  and  hypo- 
glossal  nerves  should  be  cut  through,  near  the  base  of  the  skull ; 
then  by  careful  dissection  the  superior  cervical  ganglion  can  be 
traced  out. 

CEBVICAL  GAN-  ^n  ^ne  cervical  portion  of  the  "sympathetic  are 

QUA  OF  SYMPA-  three  ganglia,  named  from  their  position,'  superior, 
THETIC-  middle,  and  inferior. 

The  superior  cervical  ganglion,  the  largest  of  the  three,  is 
situated  near  the  base  of  the  skull,  opposite  the  second  and 
third  cervical  vertebrae,  upon  the  rectus  capitis  anticus  major,  and 
lies  behind,  and  on  the  inner  side  of  the  internal  carotid  artery. 
It  is  of  a  reddish-grey  colour  like  the  other  ganglia,  of  an  elongated 
oval  shape,  varying  in  length  from  one  to  two  inches. 

To  facilitate  the  description  of  its  several  branches',  we  divide 
them  into  an  upper,  a  lower,  an  external,  an  internal,  and  an 
anterior  set — 

a.  Its  tipper  or  cranial  branch  runs  with  the  internal  carotid  a.  into 
the  carotid  canal  of  the  temporal  bone,  and  there  divides  into  two 
branches,  an  outer  and  an  inner.  The  outer  and  larger  branch  accom- 
panies the  artery  through  its  bony  canal,  ramifies  upon  it  by  the  side  of 
the  body  of  the  sphenoid,  and  so  constitutes  the  '  CAROTID  PLEXUS.'  ! 
Trom  this  outer  branch  a  filament  proceeds  to  the  Gasserian  ganglion  ; 
another  to  the  sixth  cranial  nerve  ;  a  third  joins  the  great  petrosal 

1  A  small  ganglion,  the  carotid  ganglion,  is  sometimes  met  with  in  this  plexus 
on  the  under  aspect  of  the  artery. 


152 


SYMPATHETIC   NERVE   IN   THE   NECK. 


branch  of  the  facial,  and  forms  the  Vidian  nerve,  and  thus  communicates 
with  the  spheno-palatine  ganglion.     It  also  communicates  in  the  carotid 

FIG.  36. 


N.  to  great  petrosal .    . 
N.  to  lesser  petrosal .    . 

N.  to  Eustachian  tube  . 
Ns.  to  carotid  plexus   . 

Chorda  tympani  .    .    . 
N.  to  stylo-liyoid      .    . 

N.  to  digastricus      .    . 
Petrous  ganglion     .    . 

Carotid  plexus     .    .    . 

Branch  to  pharyngeal 
plexus 

Lingual  branch   .    .    . 
Ganglion  of  the  trunk  . 


Pharyngeal  n.     . 


Superior  laryngeal 


Crangliform  enlarge- 
ment. 

N.  to  fenestn  ovalis. 

N.  to  fenestra  ro- 
tunda. 

Tympanic  n. 


Auricular  n. 
Glosso-pharyngeal  n. 

Jugular  ganglion  of 
do. 

Pneumogastric. 
Ganglion  of  root. 


Spinal  accessory. 


Hypoglossal. 


Supr.  cervical  g»n- 

glion. 
1st  cervical  n. 

Br.  to  ganglion  of 
trunk. 

2nd  cervical  n. 


DIAGEAM  OF  THE  COMMUNICATIONS  OF  THE  FACIAL,  GLOSSO-PHABYNGEAL,  PNEUMO- 
GASTBIC,  SPINAL  ACCESSORY,  HYPOGLOSSAL,  SYMPATHETIC,  AND  IHE  TWO  UPPE* 
CEIiVICAL  NEEVES. 


1.  Great  petrosal  nerve. 

2.  Lesser  do. 

3.  External       do. 


4.  Nerve  to  Stapedins  muscle. 

5.  Spheno-palatine  ganglion. 

6.  Otic  ganglion. 


canal  with  the  tympanic  branch  of  the  glosso-pharyngeal.  The  inner 
branch,  running  on  with  the  artery  to  the  cavernous  sinus,  there  forms 
another  plexus,  called  from  its  position  the  'CAVERNOUS  PLEXUS.' 


SYMPATHETIC  NERVE  IN  THE  NECK.  153 

Here  the  sympathetic  is  seen  to  communicate  with  the  third,  the 
fourth,  and  the  ophthalmic  branch  of  the  fifth  and  sixth  cranial  nerves, 
and  with  the  ophthalmic  ganglion.  Lastly,  from  both  these  plexuses 
secondary  plexuses  proceed,  of  which  the  minute  filaments  ramify  on, 
and  supply  the  coats  of,  the  terminal  branches  of  the  internal  carotid. 

b.  The  lower  branch  descends  and  joins  the  middle  cervical  ganglion 
of  the  sympathetic. 

c.  The  external  branches  are  numerous,  and  connect  the  ganglion 
with  the  ganglion  of  the  pneumogastric  and  hypoglossal  nerves,  and 
with  the  four  upper  cervical  spinal  nerves.     A  small  twig  also  joins  the 
petrosal  ganglion  of  the  glosso-pharyngeal  and  the  upper  ganglion  of 
the  pneumogastric  in  the  foramen  jugulare. 

d.  The  internal  branches  are  distributed  to  the  pharynx,  larynx,  and 
the  heart.     The  pharyngeal  branches  join  the  pharyngeal  plexus  on  the 
middle   constrictor  of  the  pharynx  :    the  laryngeal  join  the  superior 
laryngeal  nerve  ;  the  cardiac  nerves,  one  or  more  in  number — superior 
cardiac — descend  behind  the  sheath  of   the   carotid   in   front  of   the 
inferior  thyroid  artery  and  recurrent  laryngeal  nerve,  and,  entering  the 
chest,  join  the  superficial  and  deep  cardiac  plexuses. 

e.  The  anterior  branches  lie  in  front  of  the  external  carotid  artery 
and  ramify  around  this  vessel  and  its  branches,  forming  the  various 
plexuses,  and  named,  on  account  of  their  delicacy,  the  nervi  molles.     In 
some  of   these  plexuses  are  occasionally  seen  several  ganglia,  the  in- 
tercarotic,1  lingual,  temporal,  and  pharyngeal  ganglia.     They  are  con- 
nected with  the  several  ganglia  about   the  head  and  neck  ;    namely, 
the  ophthalmic,  spheno-palatine,  otic,  and  submaxillary. 

The  middle  cervical  ganglion,  the  smallest  of  the  three  ganglia, 
is  something  less  than  a  barleycorn  in  size.  It  is  situated  behind 
the  carotid  sheath,  about  the  fifth  or  sixth  cervical  vertebra,  on  or 
near  the  inferior  thyroid  artery. 

a.  It  is  connected  by  branches  with  the  superior  ganglion  above,  and 
with  the  inferior  cervical  ganglion  below. 

b.  Its  external  branches  usually  pass  outwards  to  join  the  fifth  and 
sixth  cervical  spinal  nerves. 

c.  Its  internal  branches  are  distributed  to  the  thyroid  body  and  the 
heart.     The  branches  to  the  thyroid  body  accompany  the  inferior  thyroid 

1  Situated  in  the  angle  at  the  bifurcation  of  the  common  carotid  into  the 
external  and  internal  carotid  arteries  ;  it  corresponds  in  structure  with  the  coccygeal 
gland. 


154  SYMPATHETIC  NERVE  IN  THE  NECK. 

artery,  and  join  the  superior  cardiac  nerve,  and  in  the  gland  they  com- 
municate with  the  external  and  recurrent  laryngeal  nerves.  The  middle 
cardiac  nerve,  the  largest  of  the  three  cardiac  nerves,  descends,  on  the 
right  side  behind  the  common  carotid  a.,  usually  in  front  of  the  first 
part  of  the  subclavian  artery,  into  the  chest,  when  it  lies  on  the  trachea. 
It  is  joined  by  some  cardiac  filaments  from  the  recurrent  laryngeal  nerve 
and  superior  cardiac  nerve,  and  joins  the  deep  cardiac  plexus.  On  the 
left  side  this  cardiac  nerve  enters  the  chest  between  the  left  carotid  and 
subclavian  arteries. 

In  cases  where  the  middle  cervical  ganglion  is  absent,  the  pre- 
ceding nerves  are  supplied  by  the  sympathetic  cord  connecting  the 
superior  and  inferior  ganglia. 

The  inferior  cervical  ganglion  is  of  considerable  size,  and  is 
situated  in  the  interval  between  the  base  of  the  transverse  process 
of  the  seventh  cervical  vertebra  and  the  neck  of  the  first  rib,  im- 
mediately behind  the  vertebral  artery,  and  to  the  inner  side  of  the 
superior  intercostal  artery.  Not  infrequently  it  is  coalesced  with 
the  first  dorsal  sympathetic  ganglion. 

Its  branches  are  as  follow  : — 

a.  Superior  brandies  which  pass  upwards  and  connect  it  with 
the  middle  cervical  ganglion. 

b.  Inferior  Ranches  which  descend,  some  in  front  of,  and  some 
behind,  the  subclavian  a.,  to  join  the  first  dorsal  ganglion.     One 
of  these,  the  inferior  cardiac  nerve,  passes  behind  the  subclavian  a. 
in  front  of  the  trachea,  to  join  the  deep   cardiac  plexus,  beneath, 
the  arch  of  the  aorta,  and  communicates  with  the  recurrent  laryn- 
geal and  middle  cardiac  nerves. 

c.  External  branches  which  communicate  with  the  seventh  and 
eighth    cervical  nerves ;  others  form  a  plexus  around  the  verte- 
bral artery,  which  join  with  the  fourth,  fifth,  and  sixth  cervical 
nerves. 


DISSECTION  OF  THE   THORAX. 

Before  the  several  organs  contained  in  the  thorax  are  examined, 
the  student  should  have  some  knowledge  of  its  framework.  The 
ribs  with  their  cartilages  describe  a  series  of  arcs  increasing  in 
length  from  above  downwards,  and  form,  with  the  dorsal  vertebra? 
behind  and  the  sternum  in  front,  a  barrel  of  a  conical  shape, 
broader  in  the  lateral  than  in  the  antero-posterior  diameter.  The 
spaces  between  the  ribs  are  occupied  by  the  intercostal  muscles. 
In  each  intercostal  space  there  are  two  layers  of  these  muscles, 
arranged  like  the  letter  X.  The  fibres  of  the  outer  layer  run 
obliquely  from  above  downwards  and  forwards ;  those  of  the  inner 
layer  in  the  reverse  direction.  The  base  is  closed  in  the  recent 
state  by  a  muscle — the  diaphragm — which  forms  a  muscular  par- 
tition between  the  chest  and  the  abdomen.  This  partition  is  arched 
upwards,  so  that  it  constitutes  a  vaulted  floor  for  the  chest,  and 
by  its  capability  of  alternately  falling  and  rising,  it  increases  and 
diminishes  the  capacity  of  the  thorax. 

In  front,  the  diaphragm  is  attached  to  the  ensiform  cartilage,  but 
it  slopes  posteriorly,  to  become  attached  to  the  last  rib.  The  cir- 
cumference of  the  diaphragm  is  convex  and  muscular ;  in  the  centre 
it  is  flattened  and  aponeurotic.  On  the  right  side  it  corresponds, 
in  front,  with  the  upper  border  of  the  cartilage  of  the  fifth  rib ;  on 
the  left  side  it  corresponds  with  the  upper  border  of  the  sixth  rib. 

The  upper  opening  of  the  osseous  thorax  is  bounded  posteriorly 
by  the  body  of  the  first  dorsal  vertebra,  laterally  by  the  first  ribs, 
and  in  front  by  the  upper  border  of  the  manubrium  sterni.1 

1  That  the  student  may  have  some  knowledge  of  the  diameters  of  the  chest  at 
different  situations,  the  following  measurements  have  been  taken  from  a  well- 
articulated  male  skeleton  of  the  average  height : — The  antero-posterior  diameter  at 
the  upper  opening  of  the  thorax  is  2^  inches,  at  the  articulation  of  the  manubrium 


156 


DISSECTION   OF   THE   THORAX. 


Such,  in  outline,  is  the  framework  of  the  thorax,  which  con- 
tains the  heart  with  its  large  vessels  and  the  lungs.     Its  walls  are 

FIG.  37. 


FORM   OF   THE   LUNGS,    AND   THE   EXTENT   TO   WHICH   THEY    OVERLAP   THE    HEART 
AND    ITS   VALVES. 

composed  of  different  structures — bone,  cartilage,  muscles,  and 
ligaments,  which  fulfil  two  important  conditions :  1st,  by  their 

with  the  gladiolus  it  is  4£  inches,  and  at  the  junction  of  the  gladiolus  with  the 
ensiform  cartilage  it  has  increased  to  5-f  inches.  The  transverse  diameter  of  the 
upper  opening  was  found  to  be  4|  inches  ;  between  the  second  ribs,  7  inches  ; 
between  the  third,  8^  inches ;  the  diameter  increased  in  regular  proportion  as  far 
as  the  ninth  rib,  where  it  attained  a  measurement  of  lOf  inches ;  below  this  it 
gradually  decreased.  The  upper  border  of  the  manubrium  corresponds  to  the 
second  dorsal  vertebra.  The  articulation  of  the  manubrium  and  the  gladiolus  is 
on  a  level  with  the  fourth  dorsal  vertebra ;  and,  lastly,  the  junction  of  the  ensiform 
cartilage  with  the  gladiolus  is  on  a  level  with  the  border  of  the  ninth  or  tenth 
dorsal  vertebra. 


DISSECTION   OF  THE   THORAX.  157 

solidity  and  elasticity  they  protect  the  important  organs  contained 
in  the  thorax ;  2ndly,  by  their  alternate  expansion  and  contraction 
they  act  as  mechanical  powers  of  respiration.  For  they  can  in- 
crease the  capacity  of  the  chest  in  three  directions :  in  height,  by 
the  descent  of  the  diaphragm ;  in  width,  by  the  rotation  of  the 
ribs ;  and  in  depth,  by  the  elevation  of  the  sternum. 

The  chest  of  the  female  differs  from  that  of  the  male  in  the 
following  points : — Its  general  capacity  is  less  :  the  sternum  is 
shorter ;  the  upper  opening  is  larger  in  proportion  to  the  lower ; 
the  upper  ribs  are  more  moveable,  and  therefore  permit  a  greater 
enlargement  of  the  chest  at  its  upper  part,  in  adaptation  to  the 
condition  of  the  abdomen  during  pregnancy. 

The  upper  opening  of  the  thorax  gives  passage  to  the  trachea, 
the  oesophagus,  the  large  vessels  of  the  head  and  neck  and  upper 
extremities,  viz.,  the  innominate,  the  left  carotid  and  subclavian 
arteries,  with  the  left  innominate  and  right  subclavian  and  internal 
jugular  veins,  the  superior  intercostal  and  internal  mammary 
arteries,  the  inferior  thyroid  veins,  the  sterno-hyoid,  sterno-thyroid 
and  longus  colli  muscles  of  each  side,  the  pneumogastric,  the 
left  recurrent  laryngeal,  the  phrenic  and  the  sympathetic  nerves ; 
the  cardiac  branches  of  the  sympathetic,  and  the  cardiac  branches 
of  the  pneumogastric ;  also  to  the  anterior  branch  of  the  first 
dorsal  nerve  as  it  passes  up  to  join  the  brachial  plexus,  the  thoracic 
duct,  the  thymus  gland  (in  early  life),  and,  lastly,  to  the  apices  of 
the  lungs,  which,  with  their  pleural  coverings,  rise  up  on  each 
side  into  the  neck  for  about  one  inch  and  a  half  above  the  first  rib ; 
the  interspaces  between  these  various  structures  being  occupied 
by  a  dense  fibro-cellular  tissue,  continuous  with  the  deep  cervical 
fascia. 

The  diaphragm,  which  forms  the  base  of  the  thorax,  is  pierced 
by  the  following  foramina : — the  aortic  opening,  for  the  passage  of 
the  aorta,  vena  azygos  major,  thoracic  duct ;  the  oesophageal  opening 
for  the  oesophagus,  pneumogastric  nerves,  and  oesophageal  branch 
of  the  coronaria  ventriculi  artery ;  the  foramen  quadratum,  for  the 
vena  cava  inferior,  a  branch  of  the  right  phrenic  nerve  and  lym- 
phatics from  the  liver  ;  the  right  cms  transmits  the  greater  and  lesser 
splanchnic  nerves ;  the  -left  cms,  in  addition,  transmits  the  vena 


158  TRIANGULARIS   STERNI. 

azygos  minor.  In  front  there  are  the  narrow  intervals  for  the 
passage  of  the  internal  mammary  arteries. 

An  opening  must  be  made  into  the  chest,  by 
carefully  removing  the  upper  four-fifths  of  the 
sternum,  and  the  cartilages  of  all  the  true  ribs.1  In  doing  this, 
care  must  be  taken  not  to  wound  the  pleura,  which  is  closely  con- 
nected with  the  cartilages.  On  one  side  the  internal  mammary 
artery  should  be  dissected ;  on  the  other,  removed. 

In  the  dissection   of  the  chest   let  us  take  the  parts  in  the 
following  order : — 

1.  Triangularis  sterni,  with  the  internal  mammary  artery. 

2.  Mediastina,  anterior,  middle,  and  posterior. 

3.  Pleura. 

4.  Position  and  form  of  the  lungs. 

5.  Pericardium. 

6.  Position  and  relations  of  the  heart. 

7.  Posterior  mediastinum  and  its  contents ;  namely,  the  aorta,  the  thoracic 

duct,  the  vena  azygos,  the  ossophagus,  and  pneumogastric  nerves. 

8.  Eight  and  left  brachio-cephalic  veins  and  superior  vena  cava. 

9.  Course  of  the  phrenic  nerves. 

10.  Course  and  relations  of  the  arch  of  the  aorta. 

11.  The  three  great  branches  of  the  arch. 

12.  Sympathetic  nerve. 

13.  Intercostal  muscles,  vessels  and  nerves. 

14.  Nerves  of  the  heart ;  cardiac  plexuses. 

TBIANGULAEIS  On  the  under  surface  of  the  sternum  and  carti- 

STEKNI.  lages  of  the  ribs  is  a  thin  flat  muscle,  named  the 

tricing  idaris  sterni.  It  arises  from  the  ensiform  cartilage,  the 
lower  part  of  the  side  of  the  sternum,  and  the  cartilages  of  two  or 
three  lower  true  ribs.  Its  fibres  ascend  obliquely  outwards,  and 
are  inserted  by  fleshy  digitations  into  the  lower  borders  of  the  car- 
tilages of  the  true  ribs — from  the  sixth  to  the  second.  Its  lowest 
digitation  runs  transversely  outwards,  each  successive  one,  how- 
ever, becomes  more  oblique,  so  that  the  highest  one  is  nearly  ver- 
tical in  direction.  The  muscle  is  evidently  a  continuation  upwards 

1  Those  who  are  more  proficient  in  dissection  should  not  remove  the  whole  of 
the  sternum,  but  leave  a  quarter  of  an  inch  of  its  upper  part  with  the  first  rib 
attached  to  it.  This  portion  serves  as  a  valuable  landmark,  although  it  obstructs, 
to  a  certain  extent,  the  view  of  the  subjacent  vessels. 


INTERNAL   MAMMARY   ARTERY.  159 

of  the  anterior  portion  of  the  transversalis  abdominis.  Its  action 
is  to  draw  down  the  costal  cartilages,  and  thus  it  acts  in  expiration. 
Its  nerves  come  from  the  intercostal  nerves,  its  arteries  from  the 
internal  mammary. 

INTERNAL  MAM-          This  artery  is  given  off  from  the  subclavian  in 
MARY  AETEBY.  the  first  part  of  its  course  opposite  the  thyroid 

axis.  It  passes  down  behind  the  clavicle,  and  on  entering  the  chest 
it  lies  between  the  cartilage  of  the  first  rib  and  the  pleura,  and  is 
crossed  by  the  phrenic  nerve.  It  then  descends  perpendicularly, 
about  half  an  inch  from  the  sternum,  lying  on  the  pleura  and 
behind  the  costal  cartilages ;  lower  down  it  gets  between  the  carti- 
lages of  the  ribs  and  the  triangularis  sterni,  as  far  as  the  seventh 
costal  cartilage,  where  it  divides  into  two  branches,  the  musculo- 
plirenic  and  the  superior  epigastric.  The  latter  branch  then 
enters  the  wall  of  the  abdomen  behind  the  rectus  abdominis, 
and  finally  inosculates  with  the  deep  epigastric  (a  branch  of  the 
external  iliac).  The  branches  of  the  internal  mammary  are  as 
follows : — 

a.  Arteria  comes  nervi  phrenici. — A   very   slender    artery,    which 
accompanies  the  phrenic  nerve  between  the  pleura  and  pericardium  to 
the   diaphragm,    and   anastomoses   with   the   phrenic  branches  of  the 
abdominal  aorta,  and  internal  mammary. 

b.  Mediastinal,  pericardiac,  sternal,  and  thymic. — These  branches 
supply  the  cellular  tissue  of  the  anterior  mediastinum,  the  pericardium, 
and  the  triangularis  sterni.     The  thymic  are  only  visible  in  childhood, 
and  disappear  with  the  thymus  gland. 

c.  Anterior  intercostal. — Two  for  each  intercostal  space  are  distributed 
to  the  five  or  six  upper  intercostal  spaces.     They  pass  outwards,  and 
lie  at  first  between  the  pleura  and  the  internal  intercostal  muscle,  and 
subsequently  between  the  two  intercostals.     They  inosculate  with  the 
intercostal  arteries  from  the  aorta. 

d.  The  perforating  arteries  pass  through  the  same  number  of  inter- 
costal spaces  as  the  preceding  branches,  and  supply  the  pectoral  muscle 
and  skin  of  the  chest.     In  the  female  they  are  of  large  size  (especially 
the  third),  to  supply  the  mammary  gland. 

e.  The  mi(£culo-j)krenic  branch  runs  outwards  behind  the  cartilages 
of  the  false  ribs,  pierces  the  attachment  of  the  diaphragm,  and  termi- 
nates near  the  last  intercostal  space.     It  supplies  small  branches  to  the 


160  PLEURA. 

diaphragm,  to  the  sixth,  seventh,  and  sometimes  the  eighth  intercostal 
spaces. 

Two  venas  comites  accompany  the  artery,  and  form  a  single 
trunk  at  the  upper  part  of  the  chest,  which  terminates  in  the 
brachio-cephalic  vein  of  its  own  side. 

LYMPHATIC  There  are  several  lymphatic  glands  in  the  neigh- 

GIANDS.  bourhood  of  the  internal  mammary  artery.     They 

receive  the  lymphatics  from  the  upper  part  of  the  abdominal  wall, 
the  diaphragm,  the  inner  portion  of  the  mammary  gland,  and  the 
intercostal  spaces.  On  the  right  side  they  terminate  in  the  right 
lymphatic  duct,  on  the  left  in  the  thoracic  duct.  In  disease  of  the 
inner  portion  of  the  mamma,  these  glands  may  enlarge  without 
any  enlargement  of  those  in  the  axilla. 

As  the  lungs  are  constantly  gliding  to  and  fro 
within  the  chest  they  are  provided  with  a  serous 
membrane  to  facilitate  their  motion.  This  membrane  is  termed  the 
pleura.  There  is  one  for  each  lung.  Each  pleura  forms  a  com- 
pletely closed  sac,  and,  like  all  other  serous  sacs,  has  a  parietal  and 
a  visceral  layer — that  is,  the  first  layer  lines  the  containing  walls, 
the  latter  is  reflected  over  the  contained  organ  or  viscus.  Its 
several  parts  are  named  after  the  surface  to  which  they  adhere : 
the  parietal  layer,  which  lines  the  ribs  and  intercostal  muscles,  is 
called  pleura  costalis ;  the  visceral  layer,  which  invests  the  lungs, 
pleura  pulmonis ;  between  these  two  layers  is  a  space  which  is 
termed  the  cavity  of  the  pleura. 

Each  pleura  occupies  its  own  half  of  the  thorax ;  they  do  not 
communicate  with  one  another,  nor  do  they  come  into  contact 
with  each  other,  except  for  the  short  distance  of  about  two  inches 
in  front,  behind  the  sternum. 

Unlike  the  peritoneum,  the  pleura  forms  no  folds  except  a 
small  one,  called  ligamentum  latum  pulmonis,  which  extends  from 
the  root  of  the  lung  to  the  diaphragm. 

The  pleura  costalis  (fig.  38),  in  front,  lines  part  of  the  back  of 
the  sternum  and  the  inner  surfaces  of  the  costal  cartilages ;  later- 
ally, it  is  reflected  over  the  ribs  and  the  intercostal  muscles ;  pos- 
teriorly, it  is  traced  over  the  sides  of  the  bodies  of  the  dorsal 
vertebrae  ;  thence  it  passes  to  the  back  of  the  pericardium,  over  the 


PLEURA. 


161 


posterior  aspect  of  the  root  of  the  lung.  It  may  now  be  traced,  as 
the  pleura  pidmonalis,  over  the  surface  of  the  lung,  to  which  it  is 
intimately  adherent,  into  the  fissures  between  the  lobes,  as  far  as 
the  anterior  border  of  the  lung ;  thence  round  its  pericardial  aspect 


Internal  mam- 
mary a.    .    . 


Phrenic  n. 


Internal  mam- 
mary a. 


Phrenic  n. 


(Esophagus  with 

pneumogastric  n. 
Aorta. 


DIAGBAM    OF    THE    REFLECTIONS    OF    THE    PLEURAL    SACS    IN    DOTTED    LINES. 

to  the  front  of  the  root  of  the  lung,  passing  forwards  over  the 
pericardium  to  the  back  of  the  sternum.  Its  only  reflection,  the 
ligamentum  latum  pulmonis,  has  been  already  alluded  to.  Below, 
the  pleura  covers  the  diaphragm. 

The  pleura  rises  as  a  conical  dome  into  the  base  of  the  neck, 
about  an  inch  above  the  first  rib,  and  is  strengthened  in  this 
situation  by  expansions  from  the  scaleni  muscles.1 

The  thickness  of  the  pleura  differs  :  on  the  lung  it  is  thin, 
semi-transparent,  and  firmly  adherent ;  on  the  ribs  and  diaphragm 
it  is  thick,  and  may  be  easily  separated  from  its  osseous  and 
muscular  connections.2 

1  A  slip  is  described  by  Sibson  as  passing  from  the  transverse  process  of  the 
last  cervical  vertebra,  and,  spreading  out,  is  inserted  into  the  pleural  dome  and  the 
inner  margin  of  the  first  rib. 

2  From  the  prevertebral  fascia,  a  ligamentous  band  passes  downwards  along 
the  inner  border  of  the  lung  to  be  attached  to  the  pericardium  and  the  central 

M 


162  MEDIASTINA. 

The  spaces  called  anterior  and  posterior  mediastind,  formed  by 
the  separation  of 'the  pleurae,  will  be  described  further  on. 

In  health  the  internal  surface  of  the  pleura  is  smooth,  polished, 
and  lubricated  by  moisture  sufficient  to  facilitate  the  sliding  of 
the  lung.1  When  this  surface  is  thickened  and  roughened  by 
inflammation,  the  moving  lung  produces  a  friction  sound.  When 
the  pleural  sac  is  distended  by  serum,  it  constitutes  hydro-thorax ; 
when  by  pus,  empyema ;  when  by  air,  pneumo-thorax ;  when  by 
blood,  haemo-thorax. 

Introduce  your  hand  into  the  pleural  sac,  and  ascertain  that 
the  reflection  of  the  pleura  on  to  the  diaphragm  corresponds  with 
an  imaginary  line  commencing  at  the  lower  part  of  the  sternum, 
and  sloping  along  the  cartilages  of  the  successive  ribs  down  to 
the  lower  border  of  the  last  rib.  Supposing  a  ball  to  lodge  in  the 
pleural  sac,  it  might  fall  upon  the  dome  of  the  diaphragm,  and 
roll  down  to  the  lowest  part  of  the  pleural  cavity.  The  place, 
therefore,  to  extract  it,  would  be  in  the  back,  at  the  eleventh 
intercostal  space.  This  operation  has  been  done  during  life  with 
success. 

If  a  transverse  section  were  made  through  the  chest  (see  fig. 
38),  you  would  observe  that  as  the  pleuraa  nowhere  come  into 
actual  contact,  a  space  is  left  between  them  extending  from  the 
sternum  to  the  spine,  and  which  is  larger  in  the  middle  than  in 
front  or  behind.  This  interval  is  called  by  anatomists  the  in- 
terpleural  space  or  the  mediastinum,  and  for  convenience  sake  is 
subdivided  into  three  parts — an  anterior,  middle,  and  posterior 
mediastinum. 

MEDIASTINA,  The  mediastina  are  the  spaces  which  the  two 

ANTERIOR,  MIDDLE  pleural  sacs  leave  between  them  in  the  antero- 
AND  POSTERIOR.  posterior  plane  of  the  chest,  and  which  contain 
all  the  thoracic  viscera  except  the  lungs.  There  is  an  anterior,  a 
middle,  and  a  posterior  mediastinum.  To  put  these  spaces  in  the 

tendon  of  the  diaphragm.  As  it  passes  downwards  it  embraces  the  root  of  the 
lung,  and  supports  it  in  its  proper  position.  This  band  has  been  described  as 
the  '  suspensory  ligament  of  the  diaphragm,'  by  Teutleben. 

1  The  pleura  costalis  is  covered  with  flattened  epithelial  cells ;  the  pleura 
pulmonalis  with  polyhedral  granular  cells.  (Klein.) 


MEDIASTINA. 


163 


FIG.  39. 


simplest  light,  let  us  imagine  the  heart  and  lungs  to  be  removed 
from  the  chest,  and  the  two  pleural  sacs  to  be  left  in  it  by  them- 
selves. The  two  sacs,  if  in- 
flated, would  then  appear  like 
two  bladders,  in  contact  only  in 
the  middle,  as  shown  by  the 
dotted  outlines  in  the  annexed 
scheme  (fig.  39).  The  interval 
marked  a,  behind  the  sternum, 
would  represent  the  anterior 
mediastinum;  the  interval  &,  the 
posterior  mediastinum.  Now  let 
us  introduce  the  heart  again, 
between  the  two  pleural  sacs : 
these  must  give  way  to  make  room  for  it,  so  that  the  two  sacs  are 
largely  separated  in  the  middle  line  of  the  chest ;  and  the  space 
thus  occupied  by  the  heart  and  large  vessels  takes  the  name  of  the 
middle  mediastinum. 

Looking  at  the  chest  in  front,  the  anterior  mediastinum  appears 
as  shown  in  the  diagram  (fig.  40).  It  is  not  precisely  vertical  in 
its  direction,  for  it  inclines  slightly  towards  the  left,  owing  to  the 
position  of  the  heart.  Its  area  varies :  thus  it  is  very  shallow 
from  before  backwards;  it  is  extremely  narrow  in  the  middle 
where  the  edges  of  the  lungs  nearly  meet ;  it  is  wider  above,  and 
widest  of  all  below,  where  the  lungs  diverge.  Posteriorly  it  is 
limited  by  the  pericardium  covering  the  heart,  aorta  and  its 
branches,  and  the  pulmonary  artery. 

What  parts  are  contained  in  the  anterior  mediastinum  ? — The 
remains  of  the  thymus  gland,  the  origins  of  the  sterno-hyoid, 
sterno-thyroid,  and  triangularis  sterni  muscles,  the  left  brachio- 
cephalic  vein  (which  crosses  behind  the  first  bone  of  the  sternum), 
a  few  lymphatic  glands,  and  the  left  internal  mammary  artery  and 
vein. 

The  posterior  mediastinum  (fig.  38)  is  triangular  in  shape,  placed 
in  front  of  the  dorsal  vertebrae :  it  contains  the  oesophagus,  the 
two  pneumogastric  nerves,  the  descending  aorta,  the  thoracic  duct, 
the  greater  and  smaller  azygos  veins,  the  left  superior  intercostal 

M    2 


164 


MEDIASTINA. 


vein,  and  some  lymphatic  glands.     This  space  will  be  described  in 
detail  at  a  later  stage. 

The  middle  mediastinum  is  the  largest  of  the  mediastina,  and 
contains  the  heart  enclosed  in  the  pericardium,  the  vena  cava 
superior,  the  ascending  aorta,  the  pulmonary  arteries  and  veins, 
the  phrenic  nerves  with  their  accompanying  arteries,  and  the 
bifurcation  of  the  trachea. 

FIG.  40. 


FOBM   01-   THE   LUNGS,   AND    THE   EXTENT   TO   WHICH   THHY    OVEBLAP    THE    HEART 
AND   ITS   VALVES. 

A  superior  mediastinum  has  also  been  described  comprising  that 
part  of -the  interpleural  space  which  lies  above  a  horizontal  plane, 
extending  behind  from  the  lower  part  of  the  body  of  the  fourth 
dorsal  vertebra  to  the  articulation  between  the  manubrium  and 
gladiolus  in  front.  The  contents  of  this  mediastinum  include  all 


PLEURA.  165 

those  structures  found  above  this  nearly  horizontal  plane,  and  are 
the  transverse  portion  of  the  arch  of  the  aorta  and  its  three  large 
branches,  the  trachea,  oesophagus,  and  thoracic  duct,  the  inno- 
minate veins,  superior  vena  cava,  left  recurrent  laryngeal  nerve, 
phrenic,  pneumogastric,  and  cardiac  nerves,  lymphatic  glands,  and 
the  thymus  or  its  remains. 

Before  passing  to  the  dissection  of  the  contents  of  the  thorax, 
the  student  should  carefully  trace  the  outline  of  the  free  borders 
of  the  pleurae  as  seen  in  the  front  of  the  chest.  As  the  margins  of 
the  lungs  for  all  practical  purposes  correspond  with  the  borders  of 
the  pleurae,  we  shall  confine  our  description  to  the  more  important 
of  the  two  structures,  viz.  the  lungs.  The  value  of  this  investi- 
gation is,  that  we  are  enabled  to  trace  upon  a  living  chest  the 
outlines  of  the  lungs,  and  know  what  parts  are  naturally  resonant 
on  percussion. 

Commencing  from  above  (fig.  40,  p.  164),  we  find  that  the  apex 
of  the  lung  extends  into  the  neck,  from  an  inch  to  an  inch  and  a 
half  above  the  clavicle.  This  part  of  the  lung  ascends  behind  the 
subclavian  artery  and  the  scalenus  anticus  muscle,  and  deserves 
especial  attention",'  because  it  is,  more  than  any  other,  the  seat  of 
tubercular  disease.  From  the  sternal  end  of  the  clavicles  the  lungs 
converge  towards  the  middle  line,  where  their  borders  nearly  meet 
opposite  the  junction  of  the  second  rib.  There  is  thus  little  or  no 
lung  behind  the  manubrium  sterni. 

From  the  level  of  the  second  costal  cartilage  to  the  level  of  the 
fourth,  the  inner  margins  of  each  lung  run  nearly  parallel  and 
almost  in  contact  behind  the  middle  of  the  sternum ;  consequently 
they  overlap  the  great  vessels  at  the  root  of  the  heart. 

Below  the  level  of  the  fourth  costal  cartilage  the  margins  of 
the  lungs  diverge  from  each  other,  but  not  in  an  equal  degree. 
The  left  presents  the  notch  for  the  heart,  and  follows  nearly  the 
course  of  the  fourth  costal  cartilage ;  at  the  lower  part  of  its  curve 
it  projects  more  or  less  over  the  apex  of  the  heart  like  a  little 
tongue.  The  right  descends  almost  perpendicularly  behind  the 
sternum  as  low  as  the  attachment  of  the  ensiform  cartilage,  and 
then  turning  outwards  corresponds  with  the  direction  of  the  sixth 
costal  cartilage.  Hypertrophy  of  the  heart,  or  effusion  into  the 


166  POSITION   OF  THE   LUNGS. 

pericardium,  will  not  only  raise  the  point  where  the  lungs  diverge 
above  the  ordinary  level,  but  also  increase  their  divergence ;  hence 
the  greater  dulness  on  percussion. 

POSITION  AND  The  two  lungs  are  situated  in  the  chest :  each 

FORM  OF  THE  LUNGS,  in  its  own  half  of  the  thorax,  with  the  heart, 
enclosed  in  its  pericardium,  between  them.  Each  fits  accurately 
into  the  cavity  which  contains  it.  Each,  therefore,  is  conical  in 
form ;  the  apex  projects  into  the  root  of  the  neck,  a  little  more 
than  an  inch  above  the  sternal  end  of  the  clavicle ;  the  base  is 
broad  and  rests  on  the  diaphragm,  the  posterior  part  being  thin 
and  extending  as  far  as  the  eleventh  rib.  Its  outer  surface  is  con- 
vex and  adapted  to  the  ribs ;  its  inner  surface  is  excavated,  to 
make  room  for  the  heart  in  front ;  and  behind  presents  a  deep 
fissure — liilum  pulmonis — for  the  attachment  of  the  root  of  the 
lung.  Its  posterior  surface  is  convex,  and  fits  into  the  concavity 
of  the  thorax,  on  each  side  of  the  spinal  column.  The  best  way  to 
see  the  shape  of  the  lungs  is  to  inject  them  through  the  trachea 
with  wax.  which  is  tantamount  to  taking  a  cast  of  each  thoracic 
cavity.  In  such  a  preparation,  besides  the  general  convexities 
and  concavities  alluded  to,  you  would  find  in  the  right  lung  a 
little  indentation  for  the  right  brachio-cephalic  vein ;  in  the  left 
an  indentation  for  the  arch  of  the  aorta  and  the  left  subclavian 
artery. 

Each  lung  is  divided  into  an  upper  and  a  lower  lobe  by  a  deep 
fissure,  which  commences,  behind,  about  three  inches  from  the 
apex,  and  proceeds  obliquely  downwards  and  forwards  to  the  junc- 
tion of  the  sixth  rib  with  its  cartilage  (fig.  40).  Speaking  broadly, 
nearly  the  whole  of  the  anterior  portion  of  the  lung  is  formed  by 
the  upper  lobe;  nearly  the  whole  of  the  posterior  portion  by  the 
lower  lobe.  It  should  be  noticed,  however,  that  the  upper  lobe 
of  the  right  lung  is  divided  by  a  second  fissure  which  marks  off, 
from  its  lower  part,  a  triangular  portion  called  its  middle  lobe. 

The  dimensions  of  the  right  lung  are  greater  than  those  of  the 
left  in  all  directions  except  the  vertical ;  the  reason  of  this  excep- 
tion is  the  greater  elevation  of  the  diaphragm  on  the  right  side 
by  the  liver.  On  an  average  the  right  lung  weighs  24  ounces,  the 
left  21  ounces. 


POSITION    OF   THE    HEART.  167 

The  constituents  of  the  root  of  the  lung  will  be  described 
hereafter  when  they  can  be  more  satisfactorily  displayed. 

PB^COEDIAL  The  prcecordial   region  is   the    outline    of  the 

EEGION.  heart  traced  upon  the  front  wall  of  the  chest.     It 

is  important  for  auscultatory  purposes  that  we  should  know  how 
much  of  the  heart  is  covered  and  separated  from  the  wall  of  the 
chest  by  intervening  lung  (fig.  40).  The  following  will  give  a  fair 
indication :-— '  Make  a  circle  of  two  inches  in  diameter  round  a 
point  midway  between  the  nipple  and  the  end  of  the  sternum. 
This  circle  will  define,  sufficiently  for  all  practical  purposes,  that 
part  of  the  heart  which  lies  immediately  behind  the  wall  of  the 
chest,  and  is  not  covered  by  lung  or  pleura.' l 

This  part  of  the  praecordial  region  is  naturally  less  resonant  to 
percussion,  for  it  is  here  uncovered,  except  by  pericardium  and 
loose  connective  tissue,  and  lies  close  behind  the  thoracic  wall.  In 
the  rest  of  the  praecordial  region  the  heart  is  covered  and  separated 
from  the  chest  wall  by  intervening  lung. 

Where  should  we  put  the  stethoscope  when  we  listen  to  the 
valves  of  the  heart  ?  For  practical  purposes  it  is  enough  to 
remember  that  the  mouth  of  an  ordinary-sized  stethoscope  will 
cover  a  portion  of  them  all,  if  it  be  placed  a  little  to  the  left  of 
the  mesial  line  of  the  sternum  opposite  the  third  intercostal  space 
(fig.  40,  p.  164).  They  are  all  covered  by  a  thin  portion  of  lung ; 
for  this  reason  we  ask  a  patient  to  stop  breathing  while  we  listen  to 
his  heart. 

POSITION  AND  The   heart  is  situated  obliquely  in   the   chest, 

FORM  OF  THE  between  the  lungs.     Its   base,  i.e.  the   part   by 

HEART,  which    it    is  attached,  and  from  which  its  great 

vessels  proceed,  is  directed  upwards  towards  the  right  shoulder ;  its 
apex  points  downwards  and  to  the  left,  between  the  fifth  and  sixth 
costal  cartilages.  It  is  supported,  towards  the  abdomen,  by  the 
tendinous  centre  of  the  diaphragm.  It  is  maintained  in  its  posi- 
tion by  a  membranous  bag  termed  the  pericardium,  which  is  lined 
by  a  serous  membrane  to  facilitate  its  movements.  The  pericar- 
dium must  first  claim  our  attention. 

1  Latham's  Clinical  Lectures. 


168  THE    PERICARDIUM. 

The  pericardium  is  the  conical  membranous  bag 

which  encloses  the  heart  and  the  large  vessels  at 

its  base.     It  is  broadest  below,  where  it  is  attached  to  the  tendinous 

centre  of  the  diaphragm,  and  to  the  muscular  part  in  connection 

FIG.  41. 


RELATIVE   POSITION   OF   THE    HEART   AND   ITS   VALVES   WITH    REGARD   TO 
THE    WALLS    OF    THE    CHEST. 

The  valves  are  denoted  by  curved  lines.  The  aortic  valves  are  opposite  the  third  intercostal 
space  on  the  left  side,  close  to  the  sternum.  The  pulmonary  valves  are  just  above  the 
aortic,  opposite  the  junction  of  the  third  rib  with  the  sternum.  The  mitral  valves  are 
opposite  the  third  intercostal  space,  about  one  inch  to  the  left  of  the  sternum.  The 
tricuspid  valves  lie  behind  the  middle  of  the  sternum,  about  the  level  of  the  fourth  rib. 
Aortic  murmurs,  as  shown  by  the  arrow,  are  propagated  up  the  aorta  :  mitral  murmurs, 
as  shown  by  the  arrow,  are  propagated  towards  the  apex  of  the  heart. 

with  the  tendon,  further  to  the  left  side  than  to  the  right ;  above, 
it  is  prolonged  over  the  great  vessels  of  the  heart,  about  two  inches 
from  their  origin,  and  is  connected  with  the  deep  cervical  fascia. 
On  each  side,  it  is  in  contact  with  the  pleura ;  the  phrenic  nerve 


THE    PERICARDIUM.  169 

running  down  between  them.  In  front  of  it,  is  the  anterior  media- 
stinum ;  behind  it,  is  the  posterior.  Of  the  objects  in  the  poste- 
rior mediastinum,  that  which  is  nearest  to  the  pericardium  is  the 
oesophagus  and  the  left  pneumogastric  nerve.  It  should  be  re- 
membered that  the  oesophagus  is  in  close  contact  with  the  back  of 
the  pericardium  and  left  auricle  for  nearly  two  inches ;  this  fact  ac- 
counts for  what  is  sometimes  observed  in  cases  of  pericarditis  where 
there  is  much  eifusion :  namely,  pain  and  difficulty  in  swallowing. 

The  pericardium  is  a  fibro-serous  membrane,  and  consists  of 
two  layers — an  external  or  fibrous,  and  an  internal  or  serous.  Its 
fibrous  layer,  a  dense  membrane,  constitutes  its  chief  strength,  and 
is  attached,  below,  to  the  central  tendon  and  the  adjoining  muscular 
part  of  the  diaphragm.  Above,  it  forms  eight  tubular  sheaths  for 
the  great  vessels  at  the  base  of  the  heart ;  namely,  one  for  the  vena 
cava  superior,  four  for  the  pulmonary  veins,  two  for  the  pulmonary 
arteries,  and  one  for  the  aorta.  The  serous  layer  forms  a  shut  sac. 
Its  parietal  layer  lines  the  fibrous  layer  to  which  it  is  intimately 
attached,  and  is  reflected  over  the  great  vessels  and  the  heart  to 
form  its  visceral  layer.  To  see  where  the  serous  layer  is  reflected 
over  the  vessels,  distend  the  pericardium  with  air.  Thus  you  will 
find  that  this  layer  is  reflected  over  the  aorta  as  high  as  the  com- 
mencement of  the  transverse  portion  of  the  arch  of  the  aorta.  It 
is  reflected  over  the  front  and  sides  of  the  vena  cava  superior. 

The  serous  layer  of  the  pericardium  covers  the  large  vessels  to 
an  extent  greater  than  is  generally  imagined ;  though  the  extent  is 
not  precisely  similar  in  all  bodies.  The  aorta  and  pulmonary  artery 
are  enclosed  in  a  complete  sheath,  two  inches  in  length,  so  that  these 
vessels  are  covered  all  round  by  the  serous  layer,  except  where  they 
are  in  contact.  Indeed  you  can  pass  your  finger  behind  them 
both,  through  a  foramen  bounded,  in  front,  by  the  two  great  vessels 
themselves ;  behind,  by  the  upper  part  of  the  auricles ;  and  above, 
by  the  right  pulmonary  artery.  Again,  the  back  of  the  aorta, 
where  it  lies  on  the  auricles,  is  covered  by  the  serous  pericardium. 
The  superior  cava  is  covered  all  round,  except  behind,  whore  it 
crosses  the  right  pulmonary  artery.  The  inferior  cava  within 
the  pericardium  is  partly  covered  in  front.  The  left  pulmonary 
veins  are  covered  nearly  all  round ;  the  right  less  so.  Behind  the 


170  POSITION   OF  THE   HEART. 

auricles,  chiefly  the  left,  the  serous  layer  extends  upwards  in  the 
form  of  a  pouch,  rising  above  their  upper  border,  so  as  to  be  loosely 
connected  to  the  left  bronchus.  The  object  of  these  serous  reflec- 
tions is  to  facilitate  the  free  action  of  the  heart  and  the  great 
vessels  at  its  base. 

In  the  healthy  state,  the  capacity  of  the  pericardium  nearly 
corresponds  to  the  size  of  the  heart  when  distended  to  its  utmost. 
The  healthy  pericardium,  with  the  heart  in  situ,  may  be  made  to 
hold,  in  the  adult,  about  ten  ounces  of  fluid.  The  pericardium  is 
not  extensile.  When  an  aneurism  bursts  into  it,  death  is  caused, 
not  by  loss  of  blood,  but  by  compression  of  the  heart  in  consequence 
of  the  inextensibility  of  the  pericardium. 

The  pericardium  derives  its  blood  from  the  internal  mammary, 
bronchial,  and  cesophageal  arteries;  its  nerve-supply  from  the 
phrenic  nerves. 

On  separating  the  left  pulmonary  artery  and  pulmonary  vein, 
you  will  notice  a  fold  of  serous  membrane  about  three-quarters  of 
an  inch  long  and  about  one  inch  in  depth  :  this  is  the  vestigial 
fold  of  tlie  pericardium,  described  by  Marshall.1  It  passes  from  the 
side  of  the  left  auricle,  curving  round  the  lower  left  pulmonary 
vein,  to  the  left  superior  intercostal  vein.  It  is  a  vestige  of  the 
left  v.  c.  superior  (duct  of  Cuvier)  which  exists  in  foetal  life. 

Open  the  pericardium,  and  observe  that  the  heart  is  conical 
in  form,  and  convex  everywhere  except  upon  its  lower  surface, 
which  is  flat,  and  rests  upon  the  tendinous  centre  of  the  diaphragm. 
When  the  pericardium  is  thus  laid  open,  the  following  objects  are 
exposed:  viz.  1.  Part  of  the  right  ventricle;  2.  Part  of  the  left 
ventricle  ;  3.  Part  of  the  right  auricle  with  its  appendix  over- 
lapping the  root  of  the  aorta  ;  4.  The  appendix  of  the  left  auricle 
overlapping  the  root  of  the  pulmonary  artery  ;  5.  The  aorta  ;  6. 
The  pulmonary  artery  ;  7.  The  vena  cava  superior;  8.  The  right 
and  left  coronary  arteries. 

POSITION  OF  ^h6  heart,  then,  placed  behind  the  lower  half 

THE  HEABT  —  of  the  sternum,  occupies  more  of  the  left  than  the 

CONTINUED.  riht    llalf    Qf    th 


1  '  On  the  Development  of  the  Great  Anterior  Veins  in  Man  and  Mammalia, 
Pliilosopli.  Transactions,  1850. 


POSITION    OF   THE    HEART.  171 

dinous  centre  of  the  diaphragm,  which  is  a  little  below  the  lowest 
part  of  the  fifth  rib.  At  each  contraction  the  apex  of  the  heart 
may  be  felt  beating  between  the  cartilages  of  the  fifth  and  sixth 
ribs,  about  two  inches  below  the  nipple  and  an  inch  to  its  sternal 
side,  or  about  three  and  a  half  inches  to  the  left  of  the  middle  of 
the  sternum.  Speaking  broadly,  the  base  corresponds  with  a  line 
drawn  across  the  sternum  along  the  upper  borders  of  the  third 
costal  cartilages.  The  right  border  of  the  heart  is  formed  almost 
Entirely  by  the  free  margin  of  the  right  auricle,  and,  when  dis- 
tended, bulges  nearly  an  inch  to  the  right  of  the  sternum.  The 
left  border  of  the  heart  is  formed  by  the  round  border  of  the  left 
ventricle,  and  reaches  from  a  point,  commencing  at  the  second 
left  intercostal  space,  to  a  point  placed  two  inches  below  the 
nipple  and  an  inch  to  its  sternal  side.  The  horizontal  border  is 
formed  by  the  sharp  margin  of  the  right  ventricle,  and  extends 
from  the  sternal  attachment  of  the  fifth  right  costal  cartilage,  to 
meet  the  lowest  point  of  the  left  margin. 

The  normal  position  which  the  cardiac  valves  hold  to  the 
thoracic  walls  is  difficult  to  define  with  precision,  and  this  pro- 
bably accounts  for  the  discrepancies  noticed  in  anatomical  works 
on  this  subject.  The  following  relations  are  the  results  of  care- 
fully made  observations  in  the  post-mortem  room :  The  right 
auricula-ventricular  valves  are  situated  behind  "the  sternum  on 
the  level  of  the  fourth  costal  cartilage;  the  left  auricula-ventri- 
cular valves  are  opposite  the  third  intercostal  space,  about  one  inch 
to  the  left  of  the  sternum ;  the  cusps  of  these  valves  extend  as  low 
as  the  fifth  costal  cartilage.  The  pulmonary  valves  lie  immediately 
behind  the  junction  of  the  third  left  costal  cartilage  with  the  ster- 
num ;  the  aortic  valves  are  on  a  level  with  the  upper  border  of  the 
third  intercostal  space  just  at  the  left  of  the  middle  line  of  the 
sternum.1 

The  position  of  the  heart  varies  a  little  with  the  position  of  the 
body.  Of  this  anyone  may  convince  himself  by  leaning  alter- 
nately forwards  and  backwards,  by  lying  on  this  side  and  on  that, 
placing  at  the  same  time  his  hand  upon  the  prsecordial  region. 

1  Anatomists  differ  much  in  the  description  they  give  of  the  relations  of  the 
valves  to  the  thoracic  walls :  in  fact  no  two  agree  in  all  the  details. 


172  BRACHIO-CEPHALIC   VEINS. 

He  will  find  that  he  can,  in  a  slight  degree,  alter  the  place  and 
the  extent  of  the  impulse  of  the  heart.  Inspiration  and  expira- 
tion also  alter  the  position  of  the  heart.  In  inspiration  the  heart 
descends  with  the  tendinous  centre  of  the  diaphragm  about  half  an 
inch. 

The  student  should  now  make  out  the  large  vessels  in  con- 
nection with  the  base  of  the  heart,  leaving  the  consideration  of 
this  organ  to  a  later  stage  of  the  dissection. 

Before  we  can  display  the  bracbio-cephalic  veins,  the  layer  of 
the  deep  cervical  fascia  must  be  removed  which  descends  over 
them  from  the  neck  and  is  lost  upon  the  pericardium.  Their 
coats  are  intimately  connected  with  this  fascia;  and  one  of  its 
functions  appears  to  be  to  keep  the  veins  permanently  open  for 
the  free  return  of  blood  to  the  heart. 

BRACHIO-  The  right    and   left  brachio-cephalic  (innomin- 

CEPHALIC  VEINS.  ate)  veins  are  formed,  near  the  sternal  end  of  the 
clavicle,  by  the  confluence  of  the  internal  jugular  and  subclavian 
veins.  They  differ  in  their  course  and  relations,  and  must,  there- 
fore, be  described  separately. 

The  left  brachio-cephalic  vein  passes  from  the  left  side  obliquely 
behind  the  first  bone  of  the  sternum,  the  sterno-hyoid  and  thyroid 
muscles,  the  remains  of  the  thymus  gland,  towards  the  right  side,  to 
form  with  the  right  innominate  vein  the  vena  cava  superior  (fig.  42). 
It  is  about  three  inches  in  length,  and  its  direction  inclines  a  little 
downwards.  It  is  larger  than  the  right  brachio-cephalic,  and  crosses 
over  the  trachea  and  the  origins  of  the  three  primary  branches  of  the 
arch  of  the  aorta.  We  are  reminded  of  this  fact  in  some  cases  of 
aneurism  of  these  vessels — for  what  happens  ?  The  vein  becomes 
compressed  between  the  aneurism  and  the  sternum  ;  hence  the 
swelling  and  venous  congestion  of  the  parts  from  which  it  returns 
its  blood ;  namely,  of  the  left  arm,  and  the  left  side  of  the  neck. 
The  upper  border  of  the  vein  is  not  far  from  the  upper  border  of 
the  sternum  :  in  some  cases  it  lies  even  higher,  and  we  have  seen 
it  crossing  in  front  of  the  trachea  fully  an  inch  above  the  sternum. 
This  occasional  deviation  should  be  borne  in  mind  in  the  perform- 
ance of  tracheotomy. 

The  right  brachio-cephalic  vein  descends  nearly  vertically  to 


SUPEKIOR  VENA   CAVA. 


173 


join  the  superior  vena  cava,  opposite  the  first  right  intercostal 
space.  It  is  about  an  inch  and  a  half  in  length,  and  is  situated 
about  one  inch  from  the  mesial  line  of  the  sternum.  On  its  left 
side,  but  on  a  posterior  plane,  runs  the  arteria  innominata ;  on  its 
right  side  is  the  pleura.  Between  the  vein  and  the  pleura  is  the 
phrenic  nerve.  The  brachio-cephalic  veins  are  not  provided  with 
valves.  The  veins  which  generally  empty  themselves  into  the 
right  and  left  brachio-cephalic  are  as  follow : — 


The  EIGHT  B.-C.  Vein  receives : — 

The  vertebral. 

The  internal  mammary. 

The  inferior  thyroid. 


The  LEFT  B.-C.  Vein  receives  :- 

The  vertebral. 

The  internal  mammary. 

The  inferior  thyroid. 

The  superior  intercostal. 

The  pericardiac. 

The  thymic. 


FIG.  42. 


Superior  intercostal  .    . 
Internal  mammary    .    . 

Venaazygos 


Middle  thyroid. 

Internal  jugular. 

-  -  External  jugular. 

Vertebral. 

^ 

;. x^  Supra-scapular. 

Posterior  scapular. 
JB-—    Subclavian. 

Internal  mammary. 

Pericardiac  and 
thymic. 

Left  superior  inter- 
costal. 


SUPERIOR   VENA   CAVA   AND   ITS   TRIBUTARIES. 


Opening  into  the  point  of  junction  of  the  internal  jugular  and 
subclavian  veins,  on  the  right  side  is  the  right  lymphatic  duct  ;  on 
the  left  side  is  the  thoracic  duct. 

VENA  CAVA  This  is  the  great  vein  through  which  the  im- 

SUPERIOR.  pure  blood  from  the  head,  upper  extremities,  and 

chest,  returns  into  the  right  auricle.     It  is  formed  by  the  junction 
of  the  right  and  left  brachio-cephalic  veins,  which  unite  at  nearly 


174  THE   AORTA. 

a  right  angle  opposite  the  upper  part  of  the  first  intercostal  space 
on  the  right  border  of  the  sternum ;  that  is,  about  the  level  of  the 
highest  point  of  the  arch  of  the  aorta.  The  vena  cava  descends 
vertically,  with  a  slight  inclination  backwards,  to  the  upper  and 
anterior  part  of  the  right  auricle.  It  is  from  two  and  a  half  to 
three  inches  long, '  and  has  no  valves.  The  lower  half  of  it  is 
covered  by  the  pericardium ;  you  must,  therefore,  open  this  sac  to 
see  how  the  serous  layer  of  the  pericardium  is  reflected  over  the 
front  and  sides  of  the  vein.  In  respect  to  its  relations,  notice  that 
the  vein  lies  in  front  of  the  right  bronchus  and  the  right  pulmonary 
vessels  ;  and  that  it  is  overlapped  by  the  ascending  aorta,  which 
lies  to  its  left  side.  In  the  upper  half  of  its  course,  that  is,  above 
the  pericardium,  it  is  covered  on  its  right  side  by  the  pleura ;  on 
this  side,  in  contact  with  it,  descends  the  phrenic  nerve. 

Before  it  is  covered  by  the  pericardium,  the  vena  cava  receives 
the  right  vena  azygos,  which  opens  into  it  after  hooking  over  the 
right  bronchus ;  also  some  pericardiac  and  mediastinal  veins. 

COURSE  OF  THE  The  aorta  is  the  great  trunk  from  which  all  the 

AORTA.  arteries  of  the   body  carrying  arterial   blood  are 

derived.  It  commences  at  the  upper  and  back  part  of  the  left 
ventricle  of  the  heart.  It  ascends  forwards  and  to  the  right  as 
high  as  the  lower  border  of  the  first  intercostal  space  on  the  right 
side  ;  it  then  arches  backwards  towards  the  left  side  of  the  body  of 
the  second  dorsal  vertebra,  and  turning  downwards  over  the  left 
side  of  the  third,  completes  the  arch  at  the  fifth  dorsal  vertebra. 
The  aorta  descends  through  the  thorax  on  the  left  side  of  the 
bodies  of  the  remaining  dorsal  vertebras  as  far  as  the  diaphragm ; 
it  enters  the  abdomen  through  the  aortic  opening  of  the  diaphragm, 
and  descends  as  far  as  the  left  side  of  the  body  of  the  fourth 
lumbar  vertebra,  where  it  bifurcates  into  the  right  and  left  common 
iliac  arteries.  The  aorta  has  received  different  names  in  the 
various  parts  of  its  course  :  thus,  the  arched  portion  extending 
from  its  origin  at  the  left  ventricle  to  the  fifth  dorsal  vertebra,  is 
called  the  arch  of  tlie  aorfa ;  the  portion  between  this  vertebra  and 
the  diaphragm  is  the  descending  thoracic  aorta ;  and  the  remainder 
of  its  course  to  its  division  at  the  fourth  lumbar  vertebra  is  known 
as  the  abdominal  aorta. 


ARCH   OF   THE   AORTA. 


175 


COUBSE  AND  arc^  °f  *ne  aorta,  as  before  stated,  com- 

KELATIONS  OF  THE  mences   at  the  upper  part  of  the   left  ventricle, 

AKCH  OF  THE  and  describes  an  arch  which   terminates  at  the 

A*  fifth  dorsal  vertebra.     Its  origin  is  situated  be- 


FIG.  43. 


3rd  cervical  n. 

4th  cervical  n. 
Pneumogas- 
tric  n.  .    .    . 


5th  cervical  n.      — 


Cervicalis  ascendens  a. 
Scaleuus  anticus. 
Inferior  thyroid  a. 

Superficialis  colli  a. 
Phrenic  n. 

Posterior  scapular  a. 
Supra-scapular  a. 
Subclavian  a. 
Superior  intercostal  a. 
Internal  mammary  a. 
Pneumogastric  n. 

Phrenic  n. 

Appendix  of  left  anrkle. 


hind  the  pulmonary  artery,  and  on  the  left  side  of  the  middle  of 
the  sternum,  about  the  level  of  the  lower  border  of  the  third  costal 
cartilage.  The  direction  of  the  arch,  therefore,  is  from  the  sternum 
to  the  spine  and  rather  obliquely  from  right  to  left. 


176  ARCH   OF   THE   AORTA. 

For  convenience  of  description,  the  arch  of  the  aorta  is  divided 
into  an  ascending,  a  transverse,  and  a  descending  portion. 

Ascending  portion. — To  see  this  portion  of  the  aorta,  the  peri- 
cardium must  be  opened.  You  then  observe  that  this  part  of  the 
artery  is  enclosed  all  round  by  the  serous  layer  of  the  pericardium, 
except  where  it  is  in  contact  with  the  pulmonary  artery.  It  is 
about  two  inches  in  length,  and  ascends  with  a  slight  curve,  the 
convexity  looking  forwards  and  to  the  right  side,  as  far  as  the 
upper  border  of  the  second  costal  cartilage  of  the  right  side,  where 
it  lies  almost  in  contact  with  the  sternum.  Its  commencement  is 
covered  by  the  pulmonary  artery,  and  is  overlapped  by  the  appendix 
of  the  right  auricle,  and  higher  up  by  the  remains  of  the  thymus 
gland.  On  its  right  side,  but  on  a  posterior  plane,  is  the  superior 
vena  cava  and  the  right  auricle  ;  on  its  left  side,  is  the  pulmonary 
artery ;  behind  it,  are  part  of  the  right  auricle,  the  right  pulmonary 
artery  and  vein,  and  the  root  of  the  right  lung.  This  part  of  the 
arch  gives  off  the  right  and  left  coronary  arteries  for  the  supply  of 
the  heart. 

The  right  border  of  the  ascending  portion  of  the  arch  bulges  to 
the  right  of  the  sternum  to  the  extent  of  a  quarter  of  an  inch,  and 
may  be  seen  at  the  sternal  end  of  the  second  right  intercostal  space. 

The  arch  of  the  aorta  presents  partial  dilatations  in  certain 
situations.  One  of  these,  called  the  great  sinus  of  the  aorta,  is 
observed  on  the  right  side  of  the  arch,  about  the  junction  of  the 
ascending  with  the  transverse  portion  :  it  is  little  marked  in  the 
infant,  but  increases  with  age.  Three  other  dilatations  (the  sinuses 
of  Valsalva),  one  corresponding  to  each  of  the  valves  at  the  com- 
mencement of  the  aorta,  will  be  examined  hereafter. 

Transverse  portion. — This  portion  of  the  aorta  arches  from  the 
front  to  the  back  of  the  thorax,  and  extends  from  the  upper  border 
of  the  second  right  costal  cartilage  to  the  left  side  of  the  third 
dorsal  vertebra.  Its  highest  convex  portion  ascends  usually  to 
about  an  inch  below  the  upper  border  of  the  sternum,  and  its  con- 
cavity corresponds  with  the  articulation  of  the  first  and  second 
bones  of  the  sternum.  In  front,  it  is  covered  by  the  left  pleura 
and  lung,  and  is  crossed  by  the  left  phrenic,  the  left  pneumogastric, 
the  superficial  cardiac  nerves,  the  pericardiac  and  the  left  superior 
intercostal  veins.  Near  its  summit  runs  the  left  brachio-cephalic 


RELATIONS  OF  THE  ARCH  OF  THE  AORTA.          177 

vein.  Within  its  concavity,  are  the  left  bronchus,  the  bifurcation 
of  the  pulmonary  artery,  the  left  recurrent  laryngeal  nerve,  and 
the  remains  of  the  ductus  arteriosus.  The  artery  rests  upon  the 
trachea  (a  little  above  its  bifurcation),  the  deep  cardiac  plexus,  the 
O3sophagus,  the  thoracic  duct,  and  the  left  recurrent  laryngeal 
nerve.  From  the  upper  part  of  the  transverse  portion  of  the  arch 
arise  the  arteria  innominata,  the  left  carotid,  and  the  left  subclavian 
arteries ;  and  lying  in  front  of  these  arteries  is  the  left-brachio- 
cephalic  vein. 

Descending  portion. — This  part  of  the  arch  lies  upon  the  left 
side  of  the  body  of  the  fourth  dorsal  vertebra,  and  at  the  lower 
border  of  the  body  of  the  fourth,  or  the  upper  part  of  the  fifth, 
dorsal  it  takes  the  name  of  the  descending  thoracic  aorta.  On  its 
right  side,  are  the  oesophagus  and  thoracic  duct ;  on  its  left,  is  the 
pleura ;  in  front,  are  the  pleura  and  the  root  of  the  left  lung ;  behind, 
it  lies  on  the  anterior  common  ligament,  corresponding  to  the 
fourth  dorsal  vertebra. 

What  parts  are  contained  within  the  arch  of  the  aorta  ? — The 
left  bronchus,  the  right  pulmonary  artery,  the  left  recurrent  nerve, 
the  remains  of  the  ductus  arteriosus,  and  the  superficial  cardiac 
plexus  of  nerves. 

EELATIONS  OF  These  relations  vary  according  to  the  size  of  the 

THE  ARCH  OF  THE  heart,  the  obliquity  of  the  ribs,  and  the  general 
AOETA  TO  THE  development  of  the  chest.  In  a  well-formed  adult 

STERNUM.  ^g  ascending  aorta  is,  at  the  most  prominent  part 

of  its  bulge,  about  half  an  inch  behind  the  first  bone  of  the 
sternum.  The  highest  part  of  the  arch  is  about  one  inch  below 
the  upper  edge  of  the  sternum.1 

The  branches  given  off  from  the  ascending  portion  of  the  arch 

1  The  relations  of  the  arch  of  the  aorta  to  the  sternum  vary  even  in  adults, 
more  especially  if  there  be  any  hypertrophy  of  the  heart.  As  an  instance  among 
many,  we  may  mention  that  of  a  young  female  who  died  of  phthisis.  The 
position  of  the  aortic  valves  was  opposite  the  middle  of  the  sternum,  on  a  level 
with  the  middle  of  the  second  costal  articulation.  The  highest  part  of  the  arch 
was  on  a  level  with  the  upper  border  of  the  sternum  ;  the  arteria  innominata  was 
situated  entirely  in  front  of  the  trachea  ;  and  the  left  brachio-cephalic  vein  crossed 
the  trachea  so  much  above  the  sternum  that  it  would  have  been  directly  exposed 
to  injury  in  tracheotomy. 

H 


178  INNOMINATE   ARTERY. 

are  the  right  and  left  coronary  arteries,  which  pass,  one  in  front 
of,  and  the  other  behind,  the  heart  to  supply  its  muscular  tissue. 

The  right  coronary  artery  arises  from  the  anterior  sinus  of  Val- 
salva,  and  passes  to  the  right  between  the  pulmonary  artery  and 
the  right  auricular  appendix,  running  in  the  auriculo-ventricular 
groove. 

The  left  coronary  artery,  larger  than  the  preceding,  is  given  off 
from  the  left  posterior  sinus  of  Valsalva,  and  passes  between  the 
pulmonary  artery  and  left  auricular  appendix ;  it  runs  down  in 
the  anterior  interventricular  sulcus  towards  the  apex  of  the  heart. 

The  further  description  of  these  vessels  will  be  considered  in 
the  dissection  of  the  heart. 

From  the  highest  part  of  the  arch  arise  three  large  arteries  for 
the  head,  neck,  and  upper  limbs  ;  namely,  the  brachio-cephalic  or 
innominate  artery,  the  left  carotid,  and  the  left  subclavian. 

BRACHIO-CEPHA-  This,  the  largest  of  the  three,  arises  from  the 
LIC  OK  INNOMINATE  commencement  of  the  transverse  part  of  the  arch. 
ARTEHY.  j^  ascends  obliquely  towards  the  right,  and,  after 

a  course  of  about  one  inch  and  a  half  to  two  inches,  divides  behind 
the  right  sterno-clavicular  joint  into  two  arteries  of  nearly  equal 
size — the  right  subclavian  and  the  right  common  carotid. 

The  relations  of  the  innominate  artery  are  as  follow  : — In  front, 
it  has  the  manubrium  sterni,  the  right  sterno-clavicular  joint,  the 
origins  of  the  sterno-hyoid  and  thyroid  muscles,  the  remains  of 
the  thymus  gland,  the  left  brachio-cephalic  vein,  the  right  inferior 
thyroid  vein,  and  the  right  inferior  cervical  cardiac  branch  of  the 
pneumogastric  nerve.  Behind,  it  rests  upon  the  trachea.  On  its 
left  side,  are  the  left  common  carotid  and  the  remains  of  the  thymus. 
On  its  right  side,  are  the  lung  and  pleura,  the  right  brachio-cephalic 
vein,  and  the  pneumogastric  nerve.1 

With  the  anatomy  of  the  parts  before  you,  you  can  understand 
that  an  aneurism  of  the  innominate  artery  might  be  distinguished 

1  In  some  cases  the  innominate  artery  ascends  for  a  short  distance  above  the 
clavicle  before  it  divides,  lying  close  to  the  right  of  the  trachea.  We  have  already 
alluded  to  the  fact  that  it  occasionally  gives  off  a  middle  thyroid  artery  (p.  90), 
which  ascends  in  front  of  the  trachea  to  the  thyroid  body,  and  is  therefore  directly 
in  the  way  in  tracheotomy. 


LEFT   COMMON   CAROTID    ARTERY.  179 

from  an  aneurism  of  the  aorta — 1.  By  a  pulsation  in  the  neck 
between  the  sterno-mastoid  muscles,  i.e.  in  the  fossa  above  the 
sternum;  2.  By  occasional  dyspnrea  owing  to  pressure  on  the 
trachea;  3.  By  venous  congestion  in  the  left  arm;  4.  By  the 
aneurismal  thrill  being  confined  to  the  right  arm.1 

LEFT  COMMON  This  artery  arises  from  the  arch  of  the  aorta, 

CAKOTID  ABTEBY.  close  to,  and  to  the  left  of,  the  arteria  innominata. 
It  ascends  obliquely  to  the  left  sterno-clavicular  joint,  and  thence 
to  the  neck,  where  its  course  nearly  corresponds  with  the  right 
common  carotid  (p.  81).  In  front,  it  has  the  sternum,  the  left 
sterno-hyoid  and  thyroid  muscles,  the  left  brachio-cephalic  vein, 
and  the  remains  of  the  thymus  gland ;  behind,  it  has  at  first  the 
trachea,  and  higher  up  the  oasophagus  and  thoracic  duct ;  to  the 
riglit  side,  is  the  innominate  artery ;  to  the  left  side,  are  the  left 
subclavian  artery  and  left  pneumogastric  nerve. 

LEFT  SUBCLA-  This  is  the  third  branch  of  the  transverse  part 

VIAN  AKTEKY.  of  the  arch,  and  arises  from  it  opposite  the  third 

dorsal  vertebra.  It  ascends  nearly  vertically  out  of  the  chest  to 
the  inner  border  of  the  first  rib,  and  then  curves  outwards  behind 
the  scalenus  anticus.  In  front,  it  has  the  lung  covered  with  pleura, 
the  pneumogastric,  phrenic  and  cardiac  nerves,  the  left  common 
carotid,  the  left  internal  jugular  and  the  left  innominate  veins,  the 
sterno-hyoid,  sterno^thyroid,  and  sterno-mastoid  muscles.  To  its 
right  side,  are  the  left  carotid,  oesophagus,  and  trachea ;  between 
the  artery  and  the  oesophagus  is  the  thoracic  duct ;  to  its  left  side, 
is  the  lung  covered  with  pleura ;  behind  it,  are  the  longus  colli 
muscle  covering  the  vertebrae,  the  oesophagus,  thoracic  duct,  and 
the  inferior  cervical  ganglion  of  the  sympathetic.  The  upper  part 
of  its  course,  where  the  vessel  passes  in  front  of  the  apex  of  the 
lung,  has  been  described  with  the  anatomy  of  the  neck  (p.  115). 

1  If  the  innominate  artery  be  ligatured,  the  circulation  would  be  maintained 
by  the  following  collateral  branches : — 1.  Between  the  branches  of  the  two  exter- 
nal carotids,  which  anastomose  across  the  middle  line.  2.  Between  the  aortic 
intercostal  and  the  superior  intercostal.  3.  Between  the  aortic  intercostals  and 
the  internal  mammary,  long  thoracic,  alar  thoracic,  and  subscapular  arteries. 
4.  Between  the  internal  mammary  and  deep  epigastric.  5.  Between  the  inferior 
thyroid  arteries.  6.  Between  the  two  vertebrals.  7.  Between  the  two  internal 
carotid  arteries. 

N2 


180  PHRENIC    NERVES   IN    THE    CHEST. 


COUESE  OF  THE  ^e  plivenic  nerve  comes  from  the  third,  fourth, 

PHRENIC  NERVES       and  fifth  cervical    nerves,   but    chiefly  from   the 
THROUGH  THE  fourth.       It    descends    on    the    scalenus   anticus, 

gradually  inclining  to  its  inner  border,  and  enters 
the  chest  between  the  subclavian  vein  and  artery.  It  then  crosses 
over  the  internal  mammary  artery  and  runs  in  front  of  the  root  of 
the  lung,  between  the  pleura  and  the  pericardium  to  the  diaphragm 
(fig.  30),  to  the  under  surface  of  which  it  is  distributed.1 

The  phrenic  nerve  is  joined  on  the  scalenus  anticus  by  an  oifset 
from  the  fifth  cervical  branch  of  the  brachial  plexus  ;  by  another 
filament  from  the  sympathetic  nerve  ;  and  very  frequently  by  a 
small  loop  from  the  nerve  to  the  subclavius  muscle  ;  occasionally 
also  by  a  branch  from  the  descendens  noni. 

In  what  respects  do  the  phrenic  nerves  differ  from  each  other  in 
their  course  ?  —  The  right  phrenic  runs  along  the  outer  side  of  the 
brachio-cephalic  vein  and  superior  vena  cava  ;  the  left  crosses  in 
front  of  the  transverse  part  of  the  arch  of  the  aorta  ;  besides  which, 
the  left  is  rather  longer  than  the  right,  since  it  curves  over  the 
apex  of  the  heart. 

Before  the  phrenic  nerve  divides  into  branches  to  supply  the 
diaphragm,  it  sends  off  minute  filaments  to  the  pleura  and  the 
pericardium  :  after  it  has  pierced  the  diaphragm  it  distributes 
branches  to  the  peritoneum.  The  right  phrenic  gives  off  one  or 
two  filaments,  which  unite  with  some  filaments  from  the  solar 
plexus  and  form  a  small  ganglion,  from  which  branches  are  dis- 
tributed to  the  supra-renal  capsule,  the  hepatic  plexus,  and  the 
inferior  vena  cava.  The  left  phrenic  gives  off  a  branch  which 
joins  a  twig  from  the  sympathetic  near  the  cesophageal  opening  of 
the  diaphragm,  but  there  is  no  appearance  of  a  ganglion. 

Having  studied  these  anatomical  details,  consider  for  a  moment 
what  symptoms  are  likely  to  be  produced  by  an  aneurism  of  the 
arch  of  the  aorta,  or  any  of  the  primary  branches.  A  glance  at  the 
important  parts  in  the  neighbourhood  helps  to  answer  the  question. 
The  effects  will  vary  according  to  the  part  of  the  artery  which  is 

1  In  the  Museum  of  the  College  of  Surgeons  there  is  a  dissection  showing  that 
the  right  phrenic  nerve  enters  the  diaphragm  close  to  the  right  side  of  the  vena 
pava  inferior,  while  the  left  phrenic  enters  the  left  muscle  of  the  diaphragm. 


THE   POSTERIOR  MEDIASTINUM.  181 

the  seat  of  the  aneurism,  and  according  to  the  size,  the  form,  and 
the  position  of  the  tumour.  One  can  understand  that  compression 
of  the  vena  cava  superior,  or  either  of  the  brachio-cephalic  veins, 
would  occasion  congestion  and  redema  of  the  parts  from  which 
they  return  the  blood ;  that  compression  of  the  trachea  or  one  of 
the  bronchi  might  occasion  dyspnoea,  and  thus  simulate  disease  of 
the  larynx  ;  l  that  compression  of  the  oesophagus  would  give  rise 
to  symptoms  of  obstruction.  Nor  must  we  forget  the  immediate 
vicinity  of  the  thoracic  duct  and  the  recurrent  nerve,2  and  the 
effects  which  would  be  produced  by  their  compression.  Can  one, 
then,  be  surprised  that  a  disease  which  may  give  rise  to  so 
many  different  symptoms  should  be  a  fertile  source  of  fallacy  in 
diagnosis  ? 

Thus  you  can  understand  how  aneurisms  of  the  aorta  may 
prove  fatal,  by  bursting  into  the  contiguous  tubes  or  cavities ;  for 
instance,  into  the  trachea,  the  oesophagus,  the  pleura,  or  the  peri- 
cardium. You  will  see,  too,  why  an  aneurism  of  the  first  part  of 
the  arch  is  so  much  more  dangerous  than  elsewhere.  The  reason 
is,  that  in  this  part  of  its  course  the  aorta  is  covered  only  by  a  thin 
layer  of  serous  membrane.  If  an  aneurism  take  place  here,  the 
coats  of  the  vessel  soon  become  distended,  give  way,  and  allow 
the  blood  to  escape  into  the  pericardium  ;  an  occurrence  which  is 
speedily  fatal,  because,  the  pericardium  being  filled  with  blood, 
the  heart  is  prevented  from  acting. 

POSTERIOR  MEDIA-  The  posterior  mediastinum  (p.  163)  is  formed 
STINUM  AND  ITS  by  the  reflection  of  the  pleural  sac  on  each  side, 
CONTENTS.  from  the  root  of  the  lung  to  the  sides  of  the 

bodies  of  the  dorsal  vertebrae.  It  is  boundc  d  in  front  by  the  peri- 
cardium and  the  roots  of  the  lungs.  To  obtain  a  view  of  it,  cut 
away  the  ribs  nearly  as  far  as  their  angles,  draw  out  the  right  lung 
towards  the  left  side,  and  fasten  it  firmly  to  the  left  side  of  the 
thorax.  Remove  the  pleura  of  the  right  side  from  the  ribs,  and 
the  posterior  aspect  of  the  root  of  the  right  lung,  and  then  by  a 

1  In  the  Museum  of  Guy's  Hospital  there  is  a  preparation,  No.  1,487,  in  which 
laryngotomy  was  performed  under  the  circumstances  described  in  the  text. 

2  See  Med.  Gaz.,  Dec.  22nd,  1843  :  a  case  in  which  loss  of  voice  was  produced 
by  the  pressure  of  an  aneurismal  tumour  upon  the  left  recurrent  nerve. 


182  DESCENDING   THORACIC   AORTA. 

little  careful  dissection  the  space  and  the  structures  contained  in  it 
will  be  displayed.  This  mediastinum  contains  the  descending 
thoracic  aorta  with  some  of  the  right  aortic  intercostal  arteries ;  in 
front  of  the  aorta,  the  oesophagus,  with  the  pneumogastric  nerves, 
the  left  in  front  and  the  right  behind ;  on  the  right  of  the  aorta  is  the 
vena  azygos  major,  between  this  vein  and  the  aorta  is  the  thoracic 
duct ;  superiorly  is  the  trachea ;  inferiorly  are  the  splanchnic  nerves 
and  some  lymphatic  glands.  To  expose  these  last,  we  must  remove 
the  pleura,  and  a  layer  of  dense  fascia  which  lines  the  chest  outside  it. 
DESCENDING  We  have  already  traced  the  arch  of  the  aorta 

THOEACIC  AOKTA.  to  the  body  of  the  fifth  dorsal  vertebra  (p.  177). 
From  this  point,  the  aorta  descends  on  the  left  side  of  the  spine, 
gradually  approaching  towards  the  middle  line.  The  artery,  more- 
over, following  the  dorsal  spinal  curve,  is  not  vertical,  but  concave 
forwards.  Opposite  the  last  dorsal  vertebra  it  passes  between  the 
crura  of  the  diaphragm  and  enters  the  abdomen.  It  is  contained 
in  the  posterior  mediastinum ;  on  its  left  side  it  is  covered  with 
pleura  enclosing  the  left  lung,  and  below  it  has  the  oesophagus  to 
the  left;  on  its  right,  run  the  vena  azygos,  the  oesophagus,  and 
thoracic  duct ;  in  front  of  it  are,  the  root  of  the  left  lung,  and  the 
pericardium.  Lower  down  the  oesophagus  is  in  front  of  the  artery, 
and  subsequently  lies  a  little  to  its  left  side ;  behind  are  the  verte- 
bral column  and  the  vena  azygos  minor.  Its  branches  will  be 
described  presently. 

VENA  AZYGOS  This  vein  commences  in  the  abdomen  opposite 

MAJOR.  the   first   or   second   lumbar   vertebra,   by    small 

branches  from  one  of  the  lumbar  veins  of  the  right  side,  and  gene- 
rally communicates  with  the  renal,  or  the  vena  cava  itself.  This, 
indeed,  is  the  main  point  about  the  origin  of  the  vena  azygos, 
that  it  communicates  directly  or  indirectly  with  the  vena  cava 
inferior.  It  enters  the  chest  through  the  aortic  opening  of  the 
diaphragm,  and  ascends  on  the  right  side  of  the  aorta  through  the 
posterior  mediastinum,  in  front  of  the  bodies  of  the  lower  dorsal 
vertebrae,  and  over  the  right  intercostal  arteries.  When  the  vein 
reaches  the  level  of  the  third  dorsal  vertebra,  it  arches  forwards 
over  the  right  bronchus,  and  terminates  in  the  superior  vena  cava, 
just  before  this  vessel  is  covered  by  pericardium.  In  its  course  it 


VENA   AZYGOS   MINOK. 


183 


FIG.  44. 


receives  nine  or  ten  of  the  lower  intercostal  veins  of  the  right  side, 

the  spinal  veins,  the  posterior  mediastinal,  the  oesophageal  and  the 

right  bronchial  veins.   Opposite  the  sixth  or  seventh  dorsal  vertebra 

it  is  joined  by  the  left  vena  azy- 

gos.    It  is  occasionally  connected 

with  the  right  superior  intercostal 

vein. 

The  left  vena  azygos,  vena 
azygos  minor,  runs  up  the  left 
side  of  the  spine.  This  vein 
commences  in  the  abdomen  from 
one  of  the  lumbar  veins  of  the 
left  side,  or  from  the  left  renal. 
It  then  ascends  on  the  left  side 
of  the  aorta,  through  the  left 
crus  of  the  diaphragm.  On  a 
level  with  the  sixth  or  seventh 
dorsal  vertebra,  it  passes  beneath 
the  aorta  and  thoracic  duct  to 
join  the  azygos  major.  Before 
passing  beneath  the  aorta  it 
usually  communicates  with  the 
left  superior  intercostal  vein.  It 
generally  receives  six  or  seven  of 
the  lower  intercostal  veins  of  the 
left  side,  the  cesophageal  and 
mediastinal  veins.  These  azygos 
veins  are  provided  with  imperfect 
valves,  and  are  supplemental  to 
the  inferior  vena  cava. 

The  left  upper  azyyos  vein  re- 
ceives the  intercostal  veins  of  the 
left  side,  usually  from  the  fourth 
to  the  sixth ;  it  communicates 
above  with  the  left  superior  intercostal  vein,  and  opens  below,  either 
directly  into  the  vena  azygos  major,  or  indirectly  into  it  through 
the  vena  azygos  minor. 


DIAGRAM   TO    SHOW    THE    COURSE    OF    THE 
VENA   AZYGOS   AND    THE    THORACIC    DUCT. 


184  THORACIC   DUCT. 

THORACIC  DUCT  The    thoracic    duct    (fig.   43)    is    a  canal,   from 

AND  EECEPTA-  fifteen  to  eighteen  inches  long,  through  which  the 

CULUM  CHYLI.  contents  of  the  lacteal  vessels  from  the  intestines 

and  the  lymphatics  from  the  lower  limbs  are  conveyed  into  the 
blood.  These  vessels  converge  to  an  oval  dilatation,  termed  recep- 
taculum  cliyli  (cistern  of  Pecquet),  situated  a  little  to  the  right 
side  of  the  front  of  the  body  of  the  second  lumbar  vertebra,  behind 
the  aorta  and  close  to  the  right  crus  of  the  diaphragm.  Then, 
getting  to  the  right  side  of  the  aorta,  it  ascends  through  the  aortic 
opening  of  the  diaphragm  into  the  chest,  and  runs  up  the  posterior 
mediastinum,  still  along  the  right  side  of  the  aorta,  between  this 
vessel  and  the  vena  azygos  major,  and  opposite  the  sixth  dorsal 
vertebra  crosses  over  the  vena  azygos  minor.  Near  the  third 
dorsal  vertebra,  it  inclines  to  the  left  side,  and  then  passes  behind 
the  arch  of  the  aorta  and  the  oesophagus,  and  ascends  on  the  left 
side  of  this  tube,  between  it  and  the  left  pleura ;  subsequently  the 
duct  passes  up  between  the  oesophagus  and  the  left  subclavian 
artery,  as  high  as  the  seventh  cervical  vertebra,  resting  on  the 
longus  colli.  It  then  emerges  from  beneath  the  carotid  sheath, 
curves  downwards  over  the  subclavian  artery,  in  front  of  the 
scalenus  anticus,  and  opens  into  the  back  part  of  the  confluence  of 
the  left  internal  jugular  and  subclavian  veins.  The  orifice  of  the 
duct  is  guarded  .by  two  valves  which  permit  fluid  to  pass  from  the 
duct  into  the  vein,  but  not  vice  versa.  Valves,  disposed  like  those 
in  the  venous  system,  are  placed  at  short  intervals  along  the  duct, 
more  numerous  in  its  upper  part,  so  that  its  contents  can  only 
pass  upwards.1  The  diameter  of  the  duct  varies  in  different  parts 
of  its  course ;  at  its  commencement  it  is  about  three  lines  in 
diameter,  at  the  sixth  dorsal  it  is  about  two  lines,  and  it  enlarges 
again  towards  the  termination.  It  receives  the  lymphatics  from 
the  lower  extremities,  and  from  all  the  abdominal  viscera  (except 
the  convex  surface  of  the  liver  and  the  abdominal  walls) ;  above 

1  The  thoracic  duct  varies  in  size  in  different  individuals.  It  may  divide  in  its 
course  into  two  branches,  which  subsequently  reunite ;  instead  of  one  there  may 
be  several  terminal  orifices.  Instances  have  been  observed  in  which  the  duct  has 
terminated  on  the  right  instead  of  the  left  side  (Fleischmann,  Leichenoffnungen, 
1815  ;  also  Morrison,  Journal  of  Anat.,  vol.  vi.  p.  427).  It  has  been  seen  to  ter- 
minate in  the  vena  azygos  (Mtiller's  Archiv,  1834). 


(ESOPHAGUS.  185 

these  it  receives  the  lymphatics  from  the  left  side  of  the  thorax, 
the  left  lung,  the  left  side  of'  the  heart,  the  left  upper  extremity, 
and  the  left  side  of  the  head  and  neck. 

The  oesophagus  is  that  part  of  the  alimentary 
(ESOPHAGUS.  *    .;»•  t  A 

canal  which  conveys  the  food  from  the  pharynx 

to  the  stomach.  It  commences  at  the  lower  border  of  the  fifth 
cervical  vertebra,  at  the  back  of  the  cricoid  cartilage;  runs  down 
in  front  of  the  spine,  to  the  right  side  of  the  transverse  portion  of 
the  arch  of  the  aorta,  then  through  the  posterior  mediastinum  in 
front  of  the  descending  aorta,  and  passes  through  the  oesophageal 
opening  in  the  diaphragm  to  end  in  the  stomach,  opposite  the  ninth 
dorsal  vertebra.  It  is  from  nine  to  ten  inches  long.  Its  course  is 
not  exactly  straight,  for  it  describes  three  curves — one  an  antero- 
posterior,  the  other  two  lateral  curves.  In  the  neck  at  its  com- 
mencement it  lies  at  first  in  the  middle  line ;  it  then  gets  behind, 
and  a  little  to  the  left  of  the  trachea ;  in  the  chest,  i.e.  about  the 
fourth  dorsal  vertebra,  it  inclines  towards  the  right  side  to  make 
way  for  the  aorta ;  but  it  again  inclines  to  the  left  before  it  passes 
through  the  diaphragm.  Its  antero-posterior  curve  corresponds  to 
the  curve  of  the  spinal  column. 

The  oesophagus,  in  the  neck,  rests  behind,  upon  the  front  of  the 
spine  covered  by  the  longus  colli  muscle  ;  in  front,  it  has  the  trachea ; 
on  each  side,  it  is  in  relation  with  the  thyroid  body,  the  common 
carotid  (chiefly  the  left),  and  inferior  thyroid  arteries,  and  the 
recurrent  laryngeal  nerves ;  to  the  left  of  it  is  the  thoracic  duct. 

In  the  thorax,  the  oesophagus  has,  in  front,  the  trachea,  the  left 
bronchus,  the  arch  of  the  aorta,  the  left  carotid  and  left  subclavian 
arteries  ;  and,  lastly,  for  about  two  inches,  the  posterior  surfage 
of  the  pericardium  (behind  the  left  auricle)  :  this  accounts  for 
the  pain  which  is  sometimes  experienced,  in  cases  of  pericarditis, 
during  the  passage  of  food  ;  behind,  it  rests  upon  the  spinal  column, 
the  longus  colli,  the  thoracic  duct,  the  third,  fourth,  and  fifth 
intercostal  arteries  of  the  right  side ;  and,  lastly,  it  lies  in  front  of 
and  slightly  to  the  left  side  of  the  aorta  ;  laterally,  the  aorta  and 
pleura  are  to  the  left,  and  the  vena  azygos  major  to  the  right  of 
the  tube.  As  it  passes  down  in  the  interpleural  space,  it  is  in 
connection  with  both  pleurae.  The  oesophagus  is  surrounded  by  a 


186  PNEUMOGASTRIC   NERVES. 

plexus  of  nerves  formed  by  the  pneumogastric  nerves,  the  left 
being  in  front  of,  the  right  behind  it. 

The  oesophagus  is  supplied  with  blood  by  the  inferior  thyroid, 
the  oesophageal  branches  of  the  aorta,  the  coronaria  ventriculi,  and 
the  left  phrenic  artery.  It  is  supplied  with  nerves  by  the  pneumo- 
gastric and  the  sympathetic,  which  ramify  between  the  two  mus- 
cular layers.  The  oesophagus  is  composed  of  three  coats,  an  external 
or  muscular,  a  middle  or  areolar,  and  an  internal  or  mucous.  The 
muscular  coat  consists  of  an  outer  longitudinal,  and  an  inner  cir- 
cular layer  of  fibres.  The  longitudinal  layer  is  particularly  strong, 
and  arranged  in  the  upper  part  mainly  in  three  fasciculi,  an  ante- 
rior attached  to  the  vertical  ridge  on  the  cricoid  cartilage,  and  two 
lateral,  which  are  continuous  with  the  inferior  constrictor ;  these, 
lower  down,  spread  out  and  form  a  continuous  layer  round  the 
oesophagus  and  support  the  circular  fibres.  Under  the  microscope 
the  muscular  fibres  composing  the  upper  part  are  seen  to  consist 
entirely  of  the  striped  variety ;  at  the  lower  part,  almost  exclu- 
sively of  the  non-striped  variety.  The  middle  coat  is  composed  of 
areolar  tissue,  and  connects  very  loosely  the  muscular  and  mucous 
coats.  The  mucous  membrane  is  of  a  pale  colour  and  considerable 
thickness,  and  in  the  contracted  state  of  the  oesophagus  is  arranged 
in  longitudinal  folds  within  the  tube  which  lies  flattened  in  front 
of  the  spine.  On  the  surface  of  the  mucous  membrane  there  are 
numerous  minute  papillae  placed  obliquely.  It  is  lined  by  a  very 
thick  layer  of  scaly  epithelium.  In  the  submucous  tissue  are  many 
small  compound  racemose  glands — oesophageal  glands — especially 
towards  the  lower  end  of  the  oesophagus. 

„  COURSE  AND  The    course    of  the    pneumogastric   nerves   in 

BKANCHES  OF  THE  the  chest  is  not  the  same  on  both  sides.  The 
PNEUMOGASTRIC  right  pneumogastric  nerve  enters  the  chest  between 
the  subclavian  artery  and  vein,  descends  behind 
the  right  innominate  vein  by  the  side  of  the  trachea  to  the  back  of 
the  root  of  the  lung,  where  it  breaks  up  into  a  plexus  forming  the 
posterior  pulmonary  plexus.  From  this  plexus  two  cords  descend 
to  the  posterior  surface  of  the  oesophagus,  upon  which  they  divide 
into  numerous  branches  :  forming,  with  corresponding  branches  of 
the  left  pneumogastric  nerve,  the  oesophageal  plexus  (plexus  guise). 


BRANCHES   OF  THE   PNETJMOGASTRIC   IN   THE   CHEST.  187 

The  plexus  then  reunites  into  a  single  trunk,  consisting  also  of 
some  fibres  from  the  left  pneumogastric,  and  passes  into  the  abdo- 
men through  the  cesophageal  opening  in  the  diaphragm.  The  left 
pneumogastric  descends  into  the  chest  between  the  left  subclavian 
and  carotid  arteries,  and  behind  the  left  brachio-cephalic  vein. 
It  then  crosses  in  front  of  the  arch  of  the  aorta,  and  passes  behind 
the  root  of  the  left  lung  to  the  anterior  surface  of  the  ossophagus, 
upon  which  it  also  assists  to  form  a  plexus  with  the  nerve  of  the 
right  side.  The  branches  of  the  pneumogastric  nerve  in  the  chest 
are  as  follow : — 

a.  The  inferior  laryngeal  or  recurrent. — This  nerve  on  the  right  side 
turns  under  the  subclavian  and  the  common  carotid  arteries  (p.  114);  on 
the  left,  under  the  arch  of  the  aorta,  below  the  ductus  arteriosus,  and 
ascends  to  the  larynx.     It  passes  beneath  the  inferior  thyroid  artery, 
and  lying  in  the  groove  between  the  trachea  and  oesophagus,  it  enters 
the  larynx  beneath  the  lower  border  of  the  inferior  constrictor  of  the 
pharynx.     It  supplies  with  motor  nerves  all  the  muscles  which  act  upon 
the  rima  glottidis,  except  the  crico-thyroid  (supplied  by  the  external 
laryngeal  nerve).     As  they  turn  beneath  their  respective  arteries,  they 
give  off  branches  to  the  deep  cardiac  plexus  ;  also  some  small  filaments 
to  the  inferior  cervical  ganglion  of  the  sympathetic.     In  the  neck  it 
distributes    small   branches   to   the   trachea,    oesophagus,  and  inferior 
constrictor  muscle. 

b.  Cardiac  branches. — These  are  very  small,  and  join  the  cardiac 
plexuses  ;  the  right  arise  from  the  right  pneumogastric,  and  the  right 
recurrent  laryngeal,  close  to  the  trachea  ;  the  left  come  from  the  left 
recurrent  laryngeal  nerve.     On  both  sides  these  branches  pass  to  the 
deep  cardiac  plexus. 

c.  Pulmonary   branches. — These   accompany   the   bronchial    tubes. 
The  greater  number  run  behind  the  root  of  the  lung,  and  constitute 
the  posterior   pulmonary  plexus.      A  few,   forming  the  anterior  pul- 
monary plexus,  supply  the  front  part  of  the  root  of  the  lung.     Both 
these   plexuses  are  joined  by  filaments   from  the  second,   third,   and 
fourth  thoracic  ganglia  of  the  sympathetic.     The  nerves  of  the  lungs 
are,  however,  very  small,  and  cannot  be  traced  far  in  to  their  substance.1 

d.  (Eso])hageal  plexus. — Below  the  root  of  the  lung  each  pneumo- 
gastric nerve  is  subdivided  so  as  to  form  an  interlacement  of  nerves 
round    the   oesophagus   (plexus   guise).      From    this   plexus   numerous 

1  Upon  this  subject,  see  the  beautiful  plates  of  Scarpa. 


188  SYMPATHETIC   IN   THE   CHEST. 

filaments  supply  the  coats  of  the  tube  ;  but  the  majority  of  them  are 
collected  into  two  nerves — the  one,  chiefly  the  continuation  of  the  left 
pneumogastric  nerve;  lying  in  front  of  the  oesophagus  ;  the  other,  chiefly 
that  of  the  right,  lying  behind  it.  Both  nerves  pass  through  the 
oasophageal  opening  in  the  diaphragm  for  the  supply  of  the  stomach  : 
the  left  also  sending  filaments  to  join  the  hepatic  plexus  ;  the  right 
sending  branches  to  the  coeliac,  splenic  and  left  renal  plexuses. 

Having  examined  the  contents  of  the  posterior  mediastinum 
from  the  right  side,  now  do  so  from  the  left.  The  left  lung  should 
be  turned  out  of  its  cavity  and  fastened  by  hooks  towards  the  right 
side.  After  removing  the  pleura,  we  see  the  descending  thoracic 
aorta,  the  pneumogastric  nerve  crossing  the  arch  and  sending 
the  recurrent  branch  under  it;  also  the  first  part  of  the  left 
subclavian,  covered  externally  by  the  pleura.  The  pneumogastric 
nerve  must  be  traced  behind  the  root  of  the  left  lung  to  the  O3SO- 
phagus,  and  the  cesophageal  plexus  of  this  side  dissected.  Lastly, 
notice  the  lesser  vena  azygos  which  crosses  under  the  aorta  about 
the  sixth  or  seventh  dorsal  vertebra  to  join  the  vena  azygos  major. 
THORACIC  FOR-  This  portion  of  the  sympathetic  system  is  gene- 
TION  OF  THE  rally  composed  of  twelve  ganglia  covered  by  the 

SYMPATHETIC.  pleura ;  one  ganglion  being  found  over  the  head 

of  each  rib,  except  the  last  two,  which  lie  on  the  side  of  the  bodies 
of  the  vertebrae.  Often  there  are  only  ten  ganglia,  in  consequence 
of  two  of  them  being  fused  here  and  there.  The  first  thoracic 
ganglion  is  the  largest. 

The  ganglia  are  connected  together  by  thick  branches,  and 
each  ganglion  is  connected  externally  by  two  branches  with  the 
corresponding  intercostal  nerve.  The  nerves  proceeding  from  the 
ganglia  pass  inwards  to  supply  the  thoracic  and  part  of  the  abdo- 
minal viscera.  The  internal  branches  which  proceed  from  the  six 
upper  ganglia  are  small,  and  are  distributed  as  follows  (see  the 
diagram)  : — 

a.  Minute  nerves  from  the  first  and  second  ganglia  to  the  deep 
cardiac  plexus. 

b.  Minute  nerves  from  the  third  and  fourth  ganglia  to  the  pos- 
terior pulmonary  plexus. 

The  branches  arising  from  the  six  lower  ganglia  unite  to  form 


SPLANCHNIC   NERVES. 


189 


Fro.  45. 


three  nerves — the  great  splanchnic,  the  lesser,  and   the    smallest 
splanchnic  nerves. 

a.  The  great  splanchnic  nerve  is  generally  formed  by  branches 
from  the  fifth  or  sixth  to  the  tenth  ganglion,  and  also  receiving 
filaments,  according  to   Beck,  from 

all  the  thoracic  ganglia  above  the 
sixth.  They  descend  obliquely  by  the 
sides  of  the  bodies  of  the  dorsal  ver- 
tebree,  along  the  posterior  mediasti- 
num, and  unite  into  a  single  nerve, 
which  passes  through  the  correspond- 
ing cms  of  the  diaphragm,  and  joins 
the  semilunar  ganglion  of  the  abdo- 
men, sending  also  branches  to  the 
renal  and  supra-renal  plexuses. 

b.  The  lesser  splanchnic  nerve  is 
commonly  formed  by  branches  from 
the  tenth  and  eleventh  ganglia.     It 
passes  through  the  crus  of  the  dia- 
phragm  to  the  coeliac  plexus,  and 
occasionally  to  the  renal  plexus.1 

c.  The  smallest  splanchnic  nerve 
comes   from    the   twelfth   ganglion, 
passes  through  the  crus  of  the  dia- 
phragm, and  terminates  in  the  lower 
part  of  the  coeliac  and  renal  plexuses. 
(This  is  not  represented  in  the  dia- 
gram.) 

INTERCOSTAL  The    intercostal 

MUSCLES.  muscles  fill  in  the 

intervals  between  the  ribs  and  are  ar- 
ranged in  each  interval  in  two  layers, 
an  external  and  an  internal,  which  cross  each  other  like  the  letter 
X.  The  external  intercostals,  eleven  on  each  side,  run  obliquely 
from  behind  forwards,  like  the  external  oblique  muscle  of  the 

1  In  a  few  instances  we  have  traced  a  minute  filament  from  one  of  the  ganglia 
into  the  body  of  a  vertebra.     According  to  Cruveilhier  each  vertebra  receives  one. 


DIAGRAM    OF    THE    THORACIC    PORTION 
OF    THE    SYMPATHETIC. 


190  INTERCOSTAL   MUSCLES. 

abdomen.  They  connect  the  contiguous  borders  of  the  ribs, 
passing  from  the  outer  lip  of  the  rib  above  to  the  upper  border 
of  the  rib  below  :  they  extend  from  the  tubercles  of  the  ribs 
behind  to  the  costal  cartilages  in  front,  and  are  continued  for- 
wards to  the  sternum  as  a  thin  membrane.  The  internal  run  from 
before  backwards  like  the  internal  oblique,  and  pass  from  the  inner 
lip  of  the  groove  in  the  rib  above  and  from  the  costal  cartilage,  and 
are  inserted  into  the  upper  border  of  the  rib  below.  Observe  that 
a  few  fibres  of  the  inner  layer  pass  over  one  or  even  two  ribs, 
chiefly  near  the  angles  (especially  of  the  lower  ribs),  and  terminate 
upon  a  rib  lower  down.1 

Neither  of  these  layers  of  intercostal  muscles  extends  all  the 
way  between  the  sternum  and  the  spine :  the  outer  layer,  begin- 
ning at  the  spine,  ceases  at  the  cartilages  of  the  ribs ;  the  inner, 
commencing  at  the  sternum,  ceases  at  the  angles  of  the  ribs. 

The  intercostal  muscles  present  an  intermixture  of  tendinous 
and  fleshy  fibres ;  and  they  are  covered  inside  and  outside  the  chest 
by  a  glistening  fascia,  to  give  greater  protection  to  the  intercostal 
spaces. 

The  external  intercostal  muscles  elevate  the  ribs,  and  are 
therefore  muscles  of  inspiration.  The  internal  intercostal  muscles 
depress  the  ribs,  and  are  therefore  muscles  of  expiration. 

INTERCOSTAL  There  are  eleven  intercostal  arteries  on  each 

ARTERIES.  side  which  lie  between  the  internal  and  external 

intercostal  muscles.  The  two  upper  arteries  are  derived  from  the 
superior  intercostal  branch  of  the  subclavian ;  the  remaining  nine 
are  furnished  by  the  thoracic  aorta :  and  since  this  vessel  lies 
rather  on  the  left  side  of  the  spine,  the  right  intercostal  arteries 
are  longer  than  the  left.  The  upper  intercostal  arteries  from  the 
aorta  ascend  obliquely  to  reach  their  intercostal  spaces  ;  the  lower 
run  more  transversely.  They  are  given  off  from  the  back  of  the 
descending  aorta,  and  as  they  pass  outwards  across  the  bodies  of 
the  vertebras  they  are  covered  by  the  pleura,  and  the  sympathetic 
nerves ;  the  right,  in  addition,  pass  behind  the  ossophagus, 
thoracic  duct,  and  the  vena  azygos  major ;  the  left  behind  the  left 
superior  intercostal  vein  and  the  vena  azygos  minor.  Having 
1  These  irregular  muscular  bundles  are  called  the  subcostal  muscles. 


INTERCOSTAL   ARTERIES.  191 

reached  the  intercostal  space,  each  artery  divides  into  an  anterior 
and  a  posterior  branch.  The  anterior  branch  in  direction  and  size 
appears  to  be  the  continuation  of  the  common  trunk.  At  first  it 
runs  along  the  middle  of  the  intercostal  space,  lying  upon  the 
external  intercostal  muscle,  and  separated  from  the  cavity  of  the 
chest  by  the  pleura  and  intercostal  fascia.  Here,  therefore,  it  is 
liable  to  be  injured  by  a  wound  in  the  back.  But  near  the  angle 
of  the  rib  it  passes  between  the  intercostal  muscles,  and  occupies 
the  groove  in  the  lower  border  of  the  rib  above.  Here  it  gives  off 
a  small  branch,  the  collateral  intercostal,  which  runs  for  some 
distance  along  the  upper  border  of  the  rib  below.  After  supplying 
the  muscles,  the  main  trunk  anastomoses  with  the  anterior  inter- 
costal branch  of  the  internal  mammary  artery.  In  some  cases 
this  branch  is  as  large  as  the  intercostal  itself,  and  situated  so 
as  to  be  directly  exposed  to  injury  in  the  operation  of  tapping  the 
chest. 

In  its  course  along  the  intercostal  space,  each  artery  sends 
branches  to  the  intercostal  muscles  and  the  ribs.  About  midway 
between  the  sternum  and  the  spine,  each  gives  off  a  small  branch, 
which  accompanies  the  lateral  cutaneous  branch  of  the  intercostal 
nerve.  The  continued  trunk,  gradually  decreasing  in  size,  becomes 
very  small  towards  the  anterior  part  of  the  space,  and  is  placed 
more  in  the  middle  of  it.  Those  of  the  true  intercostal  spaces 
inosculate  with  branches  of  the  internal  mammary,  and  thoracic 
branches  of  the  axillary ;  those  of  the  false  run  between  the  layers 
of  the  abdominal  muscles,  and  anastomose  with  the  epigastric  and 
lumbar  arteries. 

The  posterior  or  dorsal  branch  passes  backwards  between 
the  transverse  processes  of  the  vertebrae,  on  the  inner  side  of 
the  anterior  costo-transverse  ligament,  and  is  distributed  to  the 
muscles  and  skin  of  the  back.  Each  sends  an  artery  through  the 
inter  vertebral  foramen  to  the  spinal  cord  and  its  membranes. 

On  the  right  side  the  intercostal  veins  terminate  in  the  vena 
azygos  major ;  on  the  left,  the  seven  or  eight  lower  terminate  in 
the  vena  azygos  minor,  the  remainder  in  the  left  superior  inter- 
costal vein. 

The  usual  relation  which  the  intercostal  vessels  and  nerve  bear 


192 


INTERCOSTAL    NERVES. 


DOKSAL  NERVES. 


PIG.  46. 


to  each  other  in  the  intercostal  space,  is,  that  the  vein  lies  upper- 
most, the  nerve  lowest,  and  the  artery  between  them. 

The  dorsal  nerves  are  twelve  in  number,  the 
first  emerging  between  the  first  and  second  dorsal 
vertebras,  and  do  not  form  a  plexus  as  in  the  cervical,  lumbar  and 
sacral  regions.  Each  dorsal  nerve  (like  all  the  spinal  nerves) 
arises  from  the  spinal  cord  by  two  roots,  an  anterior  or  motor,  and 
a  posterior  or  sensory.  The  sensory  root  has  a  ganglion  upon  it. 
The  two  roots  unite  in  the  intervertebral  foramen  and  form  a 
compoimd  nerve.  After  passing  through  the  foramen,  it  is  con- 
nected by  two  filaments  with 
the  sympathetic  nerve,  and  then 
divides  into  an  anterior  and  a 
posterior  branch.  The  posterior 
or  dorsal  branches  pass  back- 
wards between  the  transverse 
processes  of  the  dorsal  vertebras 
and  divide  into  internal  and 
external  branches :  the  internal 
branches  pass  between  the  multi- 
fidus  spinae  and  semispinalis  dorsi, 
pierce  the  rhomboidei  and  tra- 
pezius  muscles  ;  the  six  upper 
branches  become  cutaneous  at 
the  spinous  processes  of  the  ver- 
tebrae ;  the  six  lower  supply  only 
the  multifidus  spinae,  not  giving  off  any  cutaneous  filaments ;  the 
external  branches  pass  through  the  longissimus  dorsi  and  supply 
this  muscle,  the  ilio-costalis  and  their  continuations  and  the 
levatores  costarum  ;  the  six  lower  branches,  in  addition,  distribute 
cutaneous  filaments  to  the  skin.  These  branches  will  be  described 
more  fully  later  on  in  the  dissection  of  the  back. 

INTERCOSTAL  The  intercostal  nerves  are  the  anterior  divisions 

NERVES.  of  the  dorsal  nerves,  and  are  twelve  in  number. 

Each  nerve  receives  a  filament  from  the  sympathetic,  and  then 
proceeds  between  the  intercostal  muscles  in  company  with,  and 
immediately  below,  the  corresponding  artery.  Midway  between 


DIAGRAM    OF   A   SPINAL    NERVE. 


INTERCOSTAL   NERVES.  193 

the  spine  and  the  sternum,  they  give  off  lateral  cutaneous  branches, 
which  supply  the  skin  over  the  scapula  and  the  thorax.  The 
intercostal  nerves  terminate  in  front  in  the  anterior  cutaneous 
nerves.  In  the  anterior  part  of  the  intercostal  space  the  nerves 
lie  in  the  substance  of  the  internal  intercostal  muscles,  and  at  the 
costal  cartilages  get  to  the  inner  side  of  the  muscles,  passing 
between  them  and  the  pleura. 

The  intercostal  nerves  are  divided  into  two  sets :  the  six  upper 
are  called  the  pectoral  intercostals,  because  they  supply  the  struc- 
tures of  the  pectoral  region ;  the  six  lower,  the  abdominal  inter- 
costals, because  they  supply  the  chest  and  abdominal  walls. 

The  upper  or  pectoral  intercostal  nerves  pass  between  the 
external  and  internal  intercostal  muscl.es,  run  forwards  in  the 
substance  of  the  latter  muscle,  and  at  the  sternal  end  of  the  in- 
tercostal spaces  pierce  the  internal  intercostal  muscles  and  the 
pectoralis  major,  to  be  ultimately  distributed  to  the  skin  of  the  chest. 
The  upper  intercostal  nerves  supply  the  levatores  costarum,  serratus 
posticus  superior,  the  intercostals,  and  the  triangularis  sterni. 

The  lower  or  abdominal  intercostal  nerves  pass  like  the  upper 
nerves  between  the  intercostal  muscles  as  far  forwards  as  the  costal 
cartilages.  They  pass  behind  these,  and  then  run  between  the 
transversalis  and  internal  oblique,  as  far  as  the  outer  border  of  the 
rectus.  Piercing  the ,  sheath  of  the  muscle,  they  supply  it,  and 
subsequently  end  as  the  anterior  cutaneous  nerves  of  the  abdomen. 
They  supply  the  intercostal  muscles,  the  serratus  posticus  inferior, 
and  the  abdominal  parietal  muscles. 

Notice  that  the  first  dorsal  nerve  ascends  nearly  perpendicu- 
larly over  the  neck  of  the  first  rib  to  form  part  of  the  brachial 
plexus.  This  nerve,  however,  gives  off  a  small  branch,  the  first 
intercostal  nerve,  to  supply  the  first  intercostal  space.  This,  as  a 
rule,  has  no  lateral  cutaneous  branch. 

Intercostal  lymphatic  glands — These  are  situated  near  the  heads 
of  the  ribs  ;  there  are  some  between  the  layers  of  the  intercostal 
muscles.  They  are  of  small  size,  and  their  efferent  vessels  go  into 
the  thoracic  duct.  Some  of  the  upper  ones  on  the  right  side  pass 
into  the  right  lymphatic  duct.  We  have  seen  these  intercostal 
glands  enlarged  and  diseased  in  phthisis. 

O 


194  PULMONARY   ARTERY. 

BRONCHIAL  AND  Small  bronchial    arteries,   arising  on  the  right 

(EsopHAGEAL  side  most  frequently  from  the  first  aortic  inter- 

AKTEEIES.  costal  (third  intercostal)  artery,  and  on  the  left 

from  the  thoracic  aorta,  accompany  the  bronchial  tube  on  its 
posterior  aspect  into  the  substance  of  the  lung.1  Their  distribu- 
tion and  office  will  be  considered  with  the  anatomy  of  the  lung. 
CEsopliacjeal  arteries,  four  or  five  in  number,  proceed  from  the  front 
of  the  thoracic  aorta  to  ramify  on  the  oesophagus,  where  they 
inosculate  above  with  the  cesophageal  branches  of  the  inferior 
thyroid,  and  below  with  the  cesophageal  branches  of  the  coron- 
aria  ventriculi  and  phrenic  arteries.  Small  posterior  mediastinal 
arteries  are  given  off  from  the  posterior  part  of  the  aorta,  and 
supply  the  lymphatic  glands  and  tissues  of  the  posterior  media- 
stinum. 

Having  finished  the  posterior  mediastinum,  replace  the  lung, 
and  turn  your  attention  once  more  to  the  great  vessels  at  the  root 
of  the  heart. 

PULMONARY  This  vessel  is  about  two  inches  in  length,  and 

ARTERY.  conveys  the  venous  blood  from  the  heart  to  the 

lungs.  It  proceeds  from  the  upper  part  of  the  base  of  the  right 
ventricle,  and  passes  upwards  and  backwards  along  the  left  side 
of  the  aorta  to  the  concavity  of  the  arch  of  the  aorta,  where  it 
divides  into  two  branches,  a  right  and  a  left,  one  for  each  lung. 
At  its  origin  it  has  on  each  side  an  auricular  appendix  and  a 
coronary  artery,  and  lies  in  front  of  the  root  of  the  aorta.  The 
pulmonary  artery  and  the  aorta  are  surrounded  for  two  inches  by 
a  common  sheath  of  pericardium.  The  right  branch,  the  larger 
and  longer,  passes  horizontally  below  the  arch  of  the  aorta,  behind 
the  ascending  aorta  and  the  superior  vena  cava,  to  the  root  of  its 
lung ;  the  left  is  easily  followed  to  its  lung  by  removing  the  layer 
of  pericardium  investing  it,  when  it  will  be  found  to  pass  hori- 
zontally in  front  of  the  descending  aorta  and  the  left  bronchus  to 
the  root  of  the  left  lung. 

Search  should  be  made  for  a  short  fibrous  cord  which  connects 

1  On  the  left  side  there  are  usually  two  bronchial  arteries — a  superior,  arising 
from  the  highest  part  of  the  thoracic  aorta,  and  an  inferior,  arising  about  an  inch 
lower  down. 


CARDIAC   NERVES.  195 

the  commencement  of  the  left  pulmonary  artery  with  the  concavity 
of  the  arch  of  the  aorta.  This  cord  is  the  remains  of  the  duct  its 
arteriosus,  a  canal  which  in  foetal  life  conveyed  blood  from  the 
pulmonary  artery  to  the  aorta. 

Draw  towards  the  left  side  the  first  part  of  the  arch  of  the 
aorta,  and  dissect  the  pericardium  from  the  great  vessels  at  the 
base  of  the  heart.  Thus  a  good  view  will  be  obtained  of  the 
trachea  and  its  bifurcation  into  the  two  bronchi.  Below  the 
division  of  the  trachea  the  right  pulmonary  artery  is  seen  passing 
in  front  of  the  right  bronchus.  The  superior  vena  cava  and  aorta 
are  seen  in  front  of,  and  nearly  at  right  angles  to,  the  right  pul- 
monary artery.  The  vena  azygos  major  is  seen  arching  over  the 
right  bronchus  and  terminating  in  the  vena  cava  superior,  just 
before  this  vein  pierces  the  pericardium.  Notice,  especially,  a 
number  of  lymphatic  glands  called  bronchial,  at  the  angle  of 
bifurcation  of  the  trachea.  The  situation  of  these  glands  in  the 
midst  of  so  many  tubes  explains  the  variety  of  symptoms  which 
may  be  produced  by  their  enlargement. 

NERVES  OF  THE  The  nerves  of  the  heart  come  from  the  pneumo- 
HEAKT  AND  CAB-  gastric  and  its  recurrent  branch,  and  the  three 
DIAC  PLEXUSES.  cervical  ganglia  of  the  sympathetic.  The  pneumo- 
gastric  gives  off  (generally)  two  or  more  filaments  (cardiac)  which 
proceed  from  the  main  trunk  in  the  neck,  or  from  its  recurrent 
branch.  The  sympathetic  sends  three  (cardiac)  filaments  :  one 
from  the  upper  cervical  ganglion,  a  second  from  the  middle,  and 
a  third  from  the  lower;  and  they  are  called,  respectively,  the 
upper,  middle,  and  lower  cardiac  nerves  of  the  sympathetic. 

The  minute  and  delicate  nerves  from  these  several  sources  on 
each  side,  pass  downwards  to  the  base  of  the  heart.  They  vary 
very  much  in  their  precise  relations  to  the  great  vessels  upon 
which  they  run ;  but  speaking  generally,  it  may  be  said  that  the 
nerves  on  the  right  side  run  chiefly  behind  the  arch  of  the  aorta ; 
those  on  the  left,  in  front  of  it.  Eventually  they  form,  by  their 
mutual  subdivisions  and  interlacement,  an  intricate  network  of 
nerves,  termed,  according  to  their  position,  the  superficial  and  the 
deep  cardiac  plexus. 

The  superficial  and  smaller  cardiac  plexus  lies  in  the  concavity 

o  2 


196  CARDIAC   PLEXUS. 

of  the  arcli  of  the  aorta  in  front  of  the  right  pulmonary  artery.  It 
is  closely  connected  with  the  deep  plexus.  It  receives  the  upper 
cardiac  branch  of  the  left  sympathetic,  the  lower  cervical  cardiac 
branch  from  the  left  pneumogastric,  and  filaments  from  the  deep 
plexus.  In  it  is  usually  found  a  small  ganglion,  ganglion  of 
Wrisberg,  placed  beneath  the  arch  of  the  aorta  on  the  right  side 
of  the  ductus  arteriosus.  This  plexus  distributes  branches  to  the 
anterior  coronary  and  the  anterior  pulmonary  plexuses. 

The  deeper  and  larger  cardiac  plexus  is  situated  behind  the  arch 
of  the  aorta  in  front  of  the  bifurcation  of  the  trachea  and  imme- 
diately above  the  right  pulmonary  artery.  To  see  it  the  peri- 
cardial  covering  of  the  aorta  must  be  carefully  removed  and  the 
vessel  hooked  forwards  and  to  the  left.  This  plexus  is  formed  by 
all  the  cardiac  branches  of  the  right  and  left  sympathetic  ganglia, 
and  by  the  cardiac  branches  of  the  pneumogastric  and  recurrent 
laryngeal  nerves,  except  the  left  superior  cardiac  branch  of  the 
sympathetic  and  the  left  cervical  cardiac  branch  of  the  pneumo- 
gastric, both  of  which  pass  to  the  superficial  cardiac  plexus.  The 
branches  from  the  right  side  of  this  plexus  descend  chiefly  in  front 
of  the  pulmonary  artery  and  pass  to  the  anterior  pulmonary  plexus, 
and  to  the  anterior  coronary  plexus ;  a  few  branches  which  pass 
behind  the  pulmonary  artery  are  distributed  to  the  right  auricle 
and  to  the  posterior  coronary  plexus.  The  branches  from  the  left 
side  of  the  plexus  go  to  the  left  auricle,  the  anterior  pulmonary 
plexus,  but  chiefly  to  the  posterior  coronary  plexus. 

From  the  cardiac  plexuses,  as  a  common  centre,  the  nerves  pass 
off  to  the  heart,  forming  plexuses  around  the  coronary  arteries. 
Thus,  the  anterior  coronary  plexus  (derived  chiefly  from  the  super- 
ficial cardiac)  accompanies  the  anterior  coronary  artery.  The 
•posterior  coronary  plexus  (derived  chiefly  from  the  left  side  of  the 
deep  cardiac)  runs  with  the  posterior  coronary  artery.  The  two 
plexuses  communicate  at  the  apex  of  the  heart,  and  in  the  ventri- 
cular septum. 

It  is  not  an  easy  matter  to  trace  the  nerves  into  the  substance 
of  the  heart.  For  this  purpose  a  horse's  heart  is  the  best,  and 
previous  maceration  in  water  is  desirable.  The  nerves  in  the 
substance  of  the  heart  are  peculiar  in  this  respect ;  that  they 


CONSTITUENTS  OF  THE  ROOTS  OF  THE  LUNGS. 


197 


present  minute  ganglia  in  their  course,  which  are  presumed  to 
preside  over  the  rhythmical  contractions  of  the  heart. 

Draw  aside  the  margin  of  the  right  lung ; 
divide  the  superior  vena  cava  above  the  vena 
azygos,  and  turn  down  the  lower  part.  Remove 

FIG.  47. 


CONSTITUENTS 
OF  THE  BOOT  OF 
EACH  LUNG. 


DIAGRAM  SHOWING  THE  CONSTITUENTS  OF  THE  ROOT  OF  EACH  LUNG,  AND  THEIR 
RELATIVE  POSITION  :  ALSO  THE  POSITION  OF  THE  VALVES  OF  THE  HEART.  THE 
ARROWS  INDICATE  THE  DIRECTIONS  IN  WHICH  AORTIC  AND  MITRAL  MURMURS  ARE 
PROPAGATED. 

the  layer  of  pericardium  which  covers  the  pulmonary  veins,  and 
the  constituent  parts  of  the  root  of  the  right  lung  will  be  exposed. 
It  is  composed  of  the  pulmonary  artery,  the  pulmonary  veins, 
bronchus,  bronchial  vessels,  anterior  and  posterior  pulmonary 


198  DISSECTION    OF   THE    HEAET. 

plexuses,  and  some  lymphatics.  The  following  is  the  disposition 
of  the  large  vessels  forming  the  root  of  the  lung.  In  front  are  the 
two  pulmonary  veins  :  behind  the  veins  are  the  subdivisions  of  the 
pulmonary  artery ;  behind  the  artery  are  the  divisions  of  the 
bronchus.  From  above  downwards  they  are  disposed  thus : — On 
the  right  side  we  find — 1st,  the  bronchus ;  2nd,  the  artery ;  3rd, 
the  veins.  On  the  left,  we  find  : — 1st,  the  artery ;  2nd,  the 
bronchus ;  3rd,  the  veins — as  shown  in  fig.  47. 


DISSECTION   OF   THE   HEAET. 

The  heart  is  conical  in  form,  and  more  or  less 
convex  on  its  external  aspect,  with  the  exception 
of  that  portion  lying  on  the  tendinous  centre  of  the  diaphragm, 
which  is  flattened.  It  is  situated  obliquely  in  the  thorax  between 
the  two  lungs,  and  is  completely  surrounded  by  the  pericardium. 
It  extends  from  the  fifth  to  the  eighth  dorsal  vertebra,  with  its 
base  directed  upwards  and  to  the  right,  its  apex  downwards  and 
to  the  left,  where  during  life  it  beats  in  the  fifth  intercostal  space, 
two  inches  below  the  nipple  and  an  inch  to  its  sternal  side.  The 
position  which  the  heart  bears  to  the  thoracic  walls  has  been 
already  described  (p.  167)  ;  it  varies,  however,  in  different  sub- 
jects, and  as  a  rule  is  higher  in  the  dead  body  than  in  the  living, 
owing  to  the  shrinking  of  the  lungs. 

The  anterior  surface  of  the  heart  is  convex  and  looks  upwards, 
and  forwards ;  the  posterior  surface  is  flattened  and  rests  upon  the 
diaphragm  :  the  former  is  chiefly  formed  by  the  right  ventricle,  the 
latter  by  the  left  ventricle.  The  right  border  is  sharp  (ratmyo 
acutiis),  while  the  left  border  is  thick  and  rounded  (margo  obtusus). 
SIZE  AND  The  size  of  the  heart  is  dependent  upon  so 

WEIGHT.  many  conditions,  that  the  following  measurements 

must  be  received  with  more  or  less  limitation.  An  average  heart  will 
measure,  in  its  transverse  direction  at  the  base,  three  and  a  half 
inches ;  in  its  length,  about  five  inches ;  in  its  thickness,  two  and  a 
half  inches.  The  weight  is  from  ten  to  twelve  ounces  in  the  male, 
and  from  eight  to  ten  in  the  female ;  but  much  depends  upon  the 


THE    HEART.  199 

size  and  condition  of  the  body  generally.  As  a  rule,  the  heart 
gradually  increases  in  length,  breadth,  and  thickness  from  child- 
hood to  old  age.1 

Notice  two  longitudinal  grooves  (sulci)  on  the  front  and  back 
surfaces  of  the  heart,  which  extend  from  the  base  of  the  ventricles 
to  the  apex,  and  which  indicate  the  septum  between  the  two  ven- 
tricles ;  the  anterior  groove  lies  nearer  to  the  left  side,  the  posterior 
to  the  right  side  of  the  heart. 

A  circular  groove,  nearer  the  base,  marks  the  separation  be- 
tween the  auricles  and  ventricles.  In  the  circular  and  longitu- 
dinal furrows,  surrounded  by  more  or  less  fat,  run  the  coronary 
vessels,  the  nerves,  and  the  lymphatics. 

The  heart  is  a  double  hollow  muscular  organ;  that  is,  it  is 
composed  of  two  hearts,  a  right  and  a  left,  separated  by  a  septum, 
and  not  communicating  with  each  other  except  during  uterine, 
and  rarely  in  adult,  life.  Each  half  consists  of  two  cavities,  an 
auricle  and  a  ventricle,  which  communicate  by  a  wide  orifice,  the 
auriculo-ventricular  opening.  The  right  half  of  the  heart  propels 
venous  blood  to  the  lungs,  and  is  called  the  pulmonary ;  the  left 
propels  arterial  blood  from  the  lungs  throughout  the  body,  and  is 
called  the  systemic.  These  two  hearts  are  not  placed  apart,  be- 
cause important  advantages  result  from  their  union.  By  being 
enclosed  in  a  single  bag  they  occupy  less  room  in  the  chest ;  and 
the  action  of  their  corresponding  cavities  being  precisely  synchro- 
nous, their  fibres,  mutually  intermixing,  contribute  to  their  mutual 
support. 

The  cavities  of  the  heart  should  now  be  examined  in  the  order 
in  which  the  blood  circulates  through  them. 

This  is  situated  at  the  right  side  of  the  base  of 
the  heart,  and  forms  a  quadrangular  cavity,  the 
atrium  or  sinus  venosus,  between  the  two  venae  cavae,  from  which 
it  receives  the  blood.  From  its  front,  a  small  pouch  projects 
towards  the  left,  and  overlaps  the  root  of  the  aorta ;  this  part  is 
termed  the  appendix  auriculce,  and  resembles  a  dog's  ear  in  shape. 

1  T.  B.  Peacock,  London  and  Edinb.  Monthly  Journal  of  Medical  Science,  1846 
and  1854  ;  Clendinning,  Med.  Chir.  Trans.,  1838  ;  Beneke,  Marburger  Schriften, 
xi.,  1879. 


200  THE   RIGHT   AURICLE. 

To  see  the  interior,  make  a  horizontal  incision  through  the 
anterior  wall  from  the  apex  of  the  appendix  transversely  across 
the  cavity :  from  this  make  another  upwards  at  right  angles  into 
the  superior  vena  cava.  The  interior  is  lined  by  a  polished  mem- 
brane called  the  endocardium,  and  is  everywhere  smooth  except 
in  the  appendix,  where  the  muscular  fibres  are  collected  into  bun- 
dles, called,  from  their  resemblance  to  the  teeth  of  a  comb,  mmcnli 
pectinati.  They  radiate  from  the  auricle  to  the  edge  of  the  auriculo- 
ventricular  opening. 

The  following  objects  are  seen  on  opening  the  auricle : — 

Superior  vena  cava.  Eustachian  valve. 

Inferior  vena  cava.  Coronary  valve. 

Coronary  sinus.  Annulus  ovalis. 

Auriculo-ventricular  opening.  Fossa  ovalis. 

Foramina  Thebesii.  Tubercle  of  Lower. 

Musculi  pectinati. 

Examine  carefully  the  openings  of  the  two  vence  cavce :  they 
are  not  directly  opposite  to  each  other ;  the  superior  cava  opens 
into  the  auricle  on  a  plane  rather  in  front,  and  a  little  to  the  left, 
of  the  inferior,  so  that  its  orifice  is  opposite  to  the  auriculo-ventri- 
cular  opening.  The  inferior  cava,  after  passing  through  the  ten- 
dinous centre  of  the  diaphragm,  makes  a  slight  curve  to  the  left 
before  it  opens  into  the  lowest  part  of  the  auricle ;  its  direction 
is  upwards  and  inwards,  so  that  the  stream  of  blood  is  directed 
towards  the  auricular  septum.  The  orifice  of  each  vena  cava 
is  nearly  circular,  and  surrounded  by  circular  muscular  fibres 
continuous  with  those  of  the  auricle. 

The  posterior  wall  of  the  auricle  is  formed  by  the  partition 
between  the  auricles,  the  septum  auricidarum.  Upon  this  septum, 
above,  and  to  the  left  of  the  orifice  of  the  vena  cava  inferior,  is 
an  oval  depression  (fossa  ovalis),  bounded  by  a  prominent  border 
(annidus  ovalis).  This  depression  indicates  the  remains  of  the 
opening  (foramen  ovale)  through  which  the  blood  in  foetal  life 
passed  from  the  right  into  the  left  auricle.  After  birth  this  open- 
ing closes ;  but  if  the  closure  is  imperfect,  the  stream  of  dark 
blood  in  the  right  auricle  mixes  with  the  florid  blood  in  the  left, 
and  occasions  what  is  called  cyanosis.  A  valvular  communication, 


INTERIOR    OF   THE    RIGHT   AURICLE. 


201 


however,  not  infrequently  exists  between  the  auricles  in  this  situa- 
tion which  is  not  attended  with  indications  of  this  disease. 

A  more  or  less  noticeable  fold  of  the  lining  membrane,  the 
Stulafhian  valcej-  may  be  seen  projecting  from  the  front  margin 
of  the  v.  c.  inferior  to  the  front  border  of  the  fossa  ovalis.  It  is 
placed  between  the  inferior  vena  cava  and  the  lower  margin  of  the 
annulus  ovalis.  Curved  in  shape,  it  passes  forwards  and  ends  in 
two  cornua ;  of  which,  one  is  attached  to  the  annulus  ovalis,  the 
other  is  lost  on  the  wall  of  the  auricle.  It  consists  of  a  reduplica- 
tion of  the  endocardium  and  contains  some  muscular  tissue.  It  is 

FIG.  48. 


Anricnlo-Yentriciilar  orifice. 

F066*0T»liS 

Opening  of  the  coronary  rein 
Line  of  Enstacliian  nlre 


DIAGBAH    OF   THE    IXTEKIOH    OF    THE    BIGHT    AURICLE. 

the  remnant  of  a  valve,  which  was  of  considerable  size  in  foetal  life, 
and  served  to  direct  the  current  of  blood  from  the  v.  c.  inferior, 
through  the  foramen  ovale,  into  the  left  auricle. 

To  the  left  of  the  Eustachian  valve,  that  is,  between  its  remains 
and  the  auriculo- ventricular  opening,  is  the  orifice  of  the  cwon«i-ij 
sinus.  The  sinus  is  about  an  inch  in  length  and  receives  the  great 
cardiac  vein,  the  posterior  cardiac  vein,  and  the  oblique  vein 
(of  Marshall),  and  will  nearly  admit  the  end  of  the  little  finger. 
It  is  surrounded  by  muscular  fibres,  and  is  guarded  by  a  semi- 
circular fold  of  the  endocardium,  called  the  voice  of  Thebesim* 

1  Eustachius,  Libell.  de  Vena  sine  Part.      *  This  valve  is  occasionally  doable. 


202  THE   EIGHT   VENTRICLE. 

to  prevent  regurgitation  of  the  blood  during  the  auricular  con- 
traction. 

Here  and  there  upon  the  posterior  wall  of  the  auricle  may  be 
observed  minute  openings,  called  foramina  Thebesii :  some  being 
the  orifices  of  small  veins  returning  blood  from  the  substance  of 
the  heart ;  others  being  simple  depressions  in  the  muscular  tissue. 
To  the  left,  and  rather  in  front  of  the  orifice  of  the  vena  cava  in- 
ferior, is  the  auricitlo-ventricular  opening,  guarded  by  the  tricuspid 
valve.  It  is  oval  in  form,  and  will  admit  the  passage  of  three 
fingers.  Lastly,  between  the  orifices  of  the  superior  and  inferior 
venas  cavae  is  a  rounded  elevation,  the  tubercle  of  Lower  *  (not  seen 
in  the  diagram),  which  is  supposed  to  direct  the  current  of  blood, 
in  foetal  life,  from  the  superior  cava  to  the  auriculo-ventricular 
opening. 

The  musculi  pectinati  are  parallel  muscular  elevations  running 
across  the  inner  surface  of  the  auricular  appendix,  and  to  a  slight 
extent  also  of  the  sinus  venosus. 

EIGHT  VEN-  This  forms  the  right  border   and  about  two- 

TBICLE.  thirds   of  the   front    surface  •  of  the   heart.      To 

examine  its  interior,  a  triangular  flap  should  be  raised  from  its 
anterior  wall.  The  apex  of  this  flap  should' be  below:  one  cut 
along  the  right  edge  of  the  ventricle,  the  other  along  the  line  of 
the  ventricular  septum.  Observe  that  the  wall  of  the  ventricle  is 
much  thicker  than  that  of  the  auricle.  The  cavity  of  the  ventricle 
is  conical,  with  base  upwards  and  to  the  right.  Its  inner  wall  is 
convex,  and  is  formed  by  the  septum  ventriculorum.  The  upper 
and  front  part  presents  a  smooth  passage,  the  infundibulum  or 
conns  arteriosus,  which  leads  to  the  opening  of  the  pulmonary 
artery.  It  is  situated  to  the  left  and  in  front  of  the  auriculo- 
ventricular  opening,  and  about  three-fourths  of  an  inch  higher. 

The  following  objects  are  seen  in  the  right  ventricle  :  — 

Columnae  earner.  Auriculo-ventricular  opening. 

Chordae  tendineffi.  Pulmonary  opening — 

guarded  by  the  tricuspid  and  semilunar  valves. 

From  its  walls  project  bands  of  muscular  fibres,  columnar  carnece, 

1  Most  distinct  in  quadrupeds. 


.    TRICUSPID   VALVE.  203 

of  various  length  and  thickness,  which  cross  each  other  in  every 
direction  ;  this  muscular  network  is  generally  filled  with  coagulated 
blood.  Of  these  columnse  carneae  there  are  three  kinds :  one 
stands  out  in  relief  from  the  ventricle  ;  another  is  attached  to  the 
ventricle  by  its  extremities  only,  the  intermediate  portion  being 
free ;  a  third,  and  by  far  the  most  important  set,  called  musculi 
papillares,  is  fixed  by  one  extremity  to  the  wall  of  the  ventricle, 
while  the  other  extremity  gives  attachment  to  the  fine  tendinous 
cords,  chorda}  tendinece,  which  regulate  the  action  of  the  tricuspid 
valve.  The  number  of  these  musculi  papillares  is  equal  to  the 
number  of  the  chief  segments  of  the  valve ;  hence  there  are  three 
in  the  right,  and  two  in  the  left  ventricle.  Of  those  in  the  right 
ventricle,  one  is  attached  to  the  septum. 

There  are  two  openings  in  the  right  ventricle.  One,  the 
auricula-ventricular,  through  which  the  blood  passes  from  the  aur- 
icle, is  oval  in  form  and  placed  at  the  base  of  the  ventricle.  It  is 
surrounded  by  a  ring  of  fibrous  tissue,  to  which  is  attached  the 
tricuspid  valve. 

TRICUSPID  This  is  situated  at  the  right  auriculo- ventricular 

VALVE.  opening,  and  consists  of  three    triangular  flaps. 

Like  all  the  valves  of  the  heart,  it  is  formed  by  a  fold  of  the 
lining  membrane  (endocardium)  of  the  heart,  strengthened  by 
fibrous  tissue,  in  which  a  few  muscular  fibres  may  be  demonstrated. 
The  bases  of  the  valves  are  continuous  with  one  another,  so  that 
they  form  a  membranous  ring  between  the  auricle  and  ventricle, 
while  the  segments  project  into  the  cavity  of  the  right  ventricle. 
Of  its  three  flaps,  the  largest  or  anterior  is  so  placed,  that,  when 
not  in  action,  it  partially  covers  the  orifice  of  the  pulmonary 
artery;  another,  the  internal,  corresponds  with  the  inferior  wall 
of  the  ventricle ;  the  third,  or  posterior,  rests  upon  the  septum 
ventriculorum. 

Observe  the  arrangement  of  the  tendinous  cords  which  regulate 
the  action  of  the  valve.  First,  they  are  all  attached  to  the  ven- 
tricular surface  of  the  valve.  Secondly,  the  tendinous  cords  pro- 
ceeding from  a  given  papillary  muscle  are  attached  to  the  ad- 
jacent halves  of  two  of  the  flaps  ;  consequently,  when  the  ventricle 
contracts,  and  the  papillary  muscle  also,  the  adjacent  borders  of 


204  PULMONARY   VALVES. 

the  flaps  will  be  approximated.  Thirdly,  to  insure  the  strength 
of  every  part  of  the  valve,  the  tendinous  cords  are  inserted  at  three 
different  points  of  it  in  straight  lines ;  accordingly,  they  are  divi- 
sible into  three  sets.  Those  of  the  first,  which  are  three  or  four  in 
number,  are  attached  to  the  base  of  the  valve  ;  those  of  the  second, 
from  four  to  six,  proceed  to  the  middle  of  its  ventricular  surface ; 
those  of  the  third,  which  are  the  smallest  and  most  numerous,  are 
attached  to  its  free  margin.1 

PDLMOXAKY  OR  These  are  three  semicircular  membranous  folds, 

SEMILUNAB  like  watch-pockets,  situated  at  the  orifice  of  the 

VALVES.  pulmonary  artery.     They,  are  attached  by.  their 

convex  borders  to  the  root  of  the  artery;  their  free  edges  look 
upwards,  and  present  a  festooned  border,  in  the  centre  of  which  is 
a  small  cartilaginous  body  called  the  nodulus  or  corpus  Araintii? 
The  use  of  these  bodies  is  plain.  Since  the  valves  are  semilunar, 
when  they  fall  together  they  would  not  exactly  close  the  artery ; 
there  would  be  a  space  of  a  triangular  form  left  between  them 
in  the  centre,  just  as  there  is  when  we  put  the  thumb,  fore,  and 
middle  fingers  together.  This  space  is  filled  up  by  these  nodules, 
so  that  the  closure  becomes  complete. 

The  valves,  two  anterior  and  one  posterior,  are  composed  of 
folds  of  the  endocardium,  or  lining  membrane  of  the  heart.  Between 
the  folds  is  a  thin  layer  of  fibrous  tissue,  which  is  prolonged  from 
the  fibrous  ring  at  the  orifice  of  the  artery.  This  layer  of  fibrous 
tissue,  however,  reaches  the  free  edge  of  the  valve  at  three  points 

1  The  best  mode  of  showing  the  action  of  the  valve  is  to  introduce  a  glass  tube 
into  the  pulmonary  artery,  and  then  to  pour  water  through  it  into  the  ventricle 
until  the  cavity  is  quite  distended.  By  gently  squeezing  the  ventricle  in  the  hand, 
so  as  artificially  to  imitate  its  natural  contraction,  the  tricuspid  valve  will  flap 
back  like  a  flood-gate,  and  close  the  auriculo-ventricular  opening.  In  this  way  one 
can  understand  how,  when  the  ventricle  contracts,  the  blood  catches  the  margin  of 
the  valve,  and  by  its  pressure  gives  it  the  proper  distension  and  figure  requisite  to 
block  up  the  aperture  into  the  auricle.  It  is  obvious  that  the  tendinous  cords  Will 
prevent  the  valve  from  flapping  back  into  the  auricle ;  and  this  purpose  is  assisted 
by  the  papillary  muscles,  which  nicely  adjust  the  degree  of  tension  of  the  cords  at 
a  time  when  they  would  otherwise  be  too  much  slackened  by  the  contraction  of  the 
ventricle. 

z  So  called  after  Arantius,  an  Italian  anatomist,  who  lived  towards  the  close  of 
the  sixteenth  century. 


LEFT   AURICLE.  205 

only  :  namely,  at  the  centre,  or  corpus  Arantii,  and  at  each  ex- 
tremity. Between  these  points  it  stops  short,  and  leaves  a  crescent- 
shaped  portion  of  the  valve,  which  is  thinner  than  the  rest,  and 
consists  of  the  endocardial  membrane.  This  crescent-shaped  por- 
tion, called  the  lunula,  is  not  wholly  without  fibrous  tissue ;  a  thin 
tendinous  cord  runs  along  its  free  edge,  to  give  it  additional 
strength  to  resist  the  pressure  of  the  blood.  Behind  each  of  the 
valves  the  artery  bulges  and  forms  three  slight  dilatations  called 
the  sinuses  of  Valsalva.1  These,  we  shall  presently  see,  are  more 
marked  at  the  orifice  of  the  aorta. 

The  action  of  these. valves  is  evident.  During  the  contraction 
of  the  ventricle  the  valves  lie  against  the  side  of  the  artery,  and 
offer  no  impediment  to  the  current  of  blood ;  during  its  dilatation, 
the  elasticity  of  the  distended  artery  would  force  back  the  column 
of  blood,  but  that  the  valves,  being  caught  by  the  refluent  blood, 
bag,  and  fall  together  so  as  to  close  the  tube.  The  greater  the 
pressure,  the  more  complete  is  the  closure.  The  coats  of  the  artery 
are  very  elastic  and  yielding,  while  the  valve,  like  the  circumference 
to  which  it  is  attached,  is  quite  unyielding ;  consequently,  when 
the  artery  is  distended  by  the  impulse  of  the  blood,  its  wall  is 
removed  from  the  contact  of  the  free  margin  of  the  valves,  and 
these  are  the  more  readily  caught  by  the  regurgitating  motion  of 
the  blood.  The  force  of  the  reflux  is  sustained  by  the  tendinous 
part  of  the  valves,  and  by  the  muscular  wall  of  the  ventricle  (pro- 
bably in  a  state  of  contraction).  The  valves  are  capable  of  sustain- 
ing a  weight  of  sixty-three  pounds  before  they  give  way.2  The 
thinner  portions  (lunulce)  become  placed  so  as  to  lie  side  by  side, 
each  one  with  that  of  the  adjacent  valve.  This  may  be  demonstrated 
by  filling  the  artery  with  water. 

This  is  situated  at  the  left  side  and  posterior 
part  of  the  base  of  the  heart.,  and  is  somewhat 
smaller  than  the  right  auricle.  It  consists,  like  the  right  auricle, 
of  a  cavity — the  sinus  venosus — and  the  auricular  appendix.  It  is 
quadrilateral,  and  receives  the  four  pulmonary  veins,  two  on  either 
side,  which  return  the  oxygenated  blood  from  the  lungs.  From 

1  An  Italian  anatomist,  b.  1666,  d.  1723.  -  Haller. 


206  LEFT   VENTRICLE. 

its  upper  and  left  side,  the  auricular  appendix  projects  towards  the 
right,  curling  over  the  root  of  the  pulmonary  artery.  The  auricle 
should  be  opened  by  a  horizontal  incision  along  the  ventricular 
border  of  the  auricle,  and  another  should  be  made  upwards  from 
the  centre  of  the  first  incision. 

The  interior  of  the  atrium  is  smooth  and  flat,  but  in  the 
appendix  there  are  numerous  raised  muscular  bands,  the  musculi 
pectinati.  The  interior  presents  the  following  objects  for  exam- 
ination : — 

The  orifices  of  the  four  pulmonary  veins. 

The  auriculo-ventricular  opening. 

The  musculi  pectinati. 

The  openings  of  the  pulmonary  veins  are  seen  in  the  posterior 
wall,  two  on  the  right  side  (sometimes  three),  and  two  on  the 
left  side.  They  are  not  guarded  by  valves.  Upon  the  septum 
between  the  auricles  is  a  semilunar  depression,  indicating  the 
remains  of  the  foramen  ovale.  The  auriculo-ventricular  opening, 
situated  at  the  lower  and  front  part  of  the  auricle,  is  smaller 
than  that  of  the  right  side,  and  somewhat  oval.  Its  long  axis 
is  nearly  transverse,  and,  in  the  adult,  will  admit  the  passage  of  two 
fingers.  The  'musculi  pectinati  are  also  smaller  and  fewer  than  in 
the  right  auricle. 

LEFT  YEN-  This  occupies  the  left  border,  and  forms  the 

TEICLE.  apex  of  the  heart.    One-third  of  it  only  is  seen  on 

the  anterior  surface,  the  rest  being  on  the  posterior.  To  examine 
the  interior,  raise  a  triangular  flap,  with  the  apex  below,  from  its 
front  wall.  Observe  that  its  wall  is  about  three  times  as  thick 
as  that  of  the  right  ventricle,  and  that  this  thickness  gradually 
diminishes  towards  the  apex.  The  interior  of  the  left  ventricle 
presents  the  following  objects  for  examination  : — 

Auriculo-ventricular  opening.  Auriculo-ventricular  or  mitral  valves. 

Aortic  opening.  Semilunar  valves. 

Columnae  carneffi. 

These  parts  so  closely  resemble  that  of  the  right  that  there  is 
no  necessity  to  describe  them  in  detail.  The  auriculo-ventricular 
valve  consists  of  two  flaps :  hence  its  name  mitral  or  bicuspid.  The 
larger  of  these  flaps  is  placed  between  the  aortic  and  auriculo- 


CORONARY    ARTERIES.  207 

ventricular  orifices.  'There  are  only  two  muscnli  papillares:  one 
attached  to  the  anterior,  the  other  to  the  posterior  wall  of  the 
ventricle.  They  are  thicker,  and  their  chordce  tendinece  stronger, 
than  those  of  the  right  ventricle,  but  their  arrangement  is  precisely 
similar.  From  the  upper  and  back  part  of  the  ventricle,  a  smooth 
passage  leads  to  the  orifice  of  the  aorta.  This  orifice  is  placed  in 
the  groove  between  the  two  auricles,  and  somewhat  in  front  and  to 
the  right  side  of  the  left  auriculo-ventricular  opening.  The  two 
orifices  are  close  together,  and  only  separated  by  the  larger  flap  of 
the  mitral  valve.  The  aortic  orifice  is  guarded  by  three  semilunar 
valves,  of  which  the  arrangement,  structure,  and  mode  of  action 
are  similar  to  those  of  the  pulmonary  artery.  Their  framework  is 
proportionately  stronger,  consistently  with  the  greater  strength  of 
the  left  ventricle,  and  the  greater  impulse  of  the  blood.  In  the 
sinuses  of  Valsalva  are  observed  the  orifices  of  the  two  coronary 
arteries ;  the  left  arising  from  the  sinus  behind  the  left  posterior 
segment ;  the  right  from  behind  the  anterior  segment. 

SIZE  OF  THE  ^e  circumferences  of  the  four  orifices  are  as 

AUKICULO-VENTBI-  follows  :  that  of  the  tricuspid  orifice,  4- 74  inches; 
CULAR  AND  ARTE-  that  of  the  mitral,  4  inches ;  that  of  the  pulmonary, 
BIAL  OPENINGS.  3.55  inches  .  and  that  of  ^  ^^  3.^  inches  i 

CORONARY  The  heart  is  supplied  with  blood  by  the  two 

ARTERIES.  coronary  arteries,  a  right  or  posterior,  and  a  left 

or  anterior.  They  are  about  the  size  of  a  crow's  quill.  Both  arise 
from  the  aorta  just  above  the  free  margins  of  the  two  semilunar 
valves,  and  thus  always  allow  the  passage  of  blood ;  both  run  in 
the  furrows  on  the  surface  of  the  heart ;  both  are  accompanied  by 
the  cardiac  nerves  and  by  lymphatics. 

The  anterior  or  left  coronary  artery,  the  smaller  of  the  two, 
arises  from  behind  the  left  posterior  valve  of  the  aortic  orifice.  It 
appears  between  the  pulmonary  artery  and  the  appendix  of  the 
left  auricle,  and  then  divides  into  two  branches :  one  which  seems 
the  continuation  of  the  main  trunk  and  runs  down  the  inter- 
ventricular  furrow  on  the  anterior  surface  of  the  heart  to  the 
apex ;  the  other  passes  transversely  to  the  left,  in  the  left  auriculo- 
ventricular  groove  to  the  back  of  the  heart. 

1  Dr.  Peacock,  Croonian  Lectures,  18G5. 


208  COKONAKY  VEINS  AND   SINUS. 

The  posterior  or  right  coronary  artery  arises  from  behind  the 
anterior  cusp  of  the  aortic  opening,  and  descends  obliquely 
between  the  pulmonary  artery  and  the  appendix  of  the  right 
auricle.  It  then  turns  to  the  right  in  the  groove  between  the 
right  ventricle  and  auricle  to  the  back  of  the  heart,  where  it 
divides  into  two  branches  ;  one  of  which  descends  in  the  posterior 
inter-ventricular  furrow  towards  the  apex  of  the  heart ;  the  other, 
which  appears  to  be  the  continuation  of  the  main  trunk,  runs  in 
the  left  auriculo- ventricular  groove.  Besides  these  branches,  the 
right  coronary  gives  off  a  large  branch  which  runs  along  the  free 
border  of  the  right  ventricle. 

Thus,  the  leading  trunks  of  the  coronary  arteries  run  in  the 
furrows  of  the  heart,  usually  surrounded  by  fat.  Their  numerous 
branches  supply  the  walls  of  the  auricles  and  ventricles,  and  their 
terminations  communicate  with  each  other. 

CORONARY  The  vein  which  corresponds  with  the  anterior 

VEINS  AND  SINUS.  coronary  artery  ascends  in  the  anterior  inter-ven- 
tricular sulcus,  and  then  curves  round  the  left  side  of  the  heart  in 
the  left  auriculo-ventricular  groove,  where  it  takes  the  name  of  the 
great  cardiac  vein.  This  vein  soon  dilates  into  a  large  trunk,  the 
coronary  sinus,  which  opens  at  the  back  of  the  right  auricle  below 
the  Eustachian  valve.  Another  vein,  known  as  the  posterior  cardiac, 
ascends  along  the  posterior  inter-ventricular  groove,  to  open  by 
valved  orifices  into  the  coronary  sinus;  while  others,  the  anterior 
cardiac  veins,  three  or  four  in  number,  are  seen  running  up  on  the 
anterior  surface  of  the  right  ventricle  to  terminate  directly  in  the 
right  auricle.  The  vence  Thebesii  transmit  the  blood  directly  from 
the  muscular  structure  into  the  right  auricle  by  small  apertures, 
the  foramina  Thebesii.  The  coronary  sinus  is  about  an  inch  in 
length,  and  receives  the  great  cardiac  vein,  the  posterior  cardiac 
vein,  and  the  oblique  vein  of  Marshall,  placed  on  the  posterior 
surface  of  the  left  auricle.  Its  orifice  in  the  right  auricle  is 
guarded  by  a  semilunar  valve  (valve  of  Thebesius')  to  prevent  re- 
gurgitation  of  the  blood.  It  is  covered  and  more  or  less  supported 
in  its  course  by  muscular  fibres  passing  from  one  auricle  to  the 
other. 

The  lymphatics  of  the  heart  pass  mainly  into  a  trunk  which 


THE   HEART.  209 

runs  in  the  anterior  inter-ventricular  groove,  and  then,  passing 
into  the  glands  between  the  aorta  and  trachea,  opens  into  the  right 
lymphatic  duct :  other  smaller  lymphatics  pass  into  the  thoracic 
duct. 

The  nerves  are  derived  from  the  cardiac  plexuses,  which  have 
been  already  described,  p.  195. 

FIBROUS  RINGS  What  may  be   termed  the  fibrous  skeleton  of 

OF  THE  HEART.  the  heart,  consists  of  four  rings,  which  surround, 
respectively,  the  four  orifices  at  its  base :  namely,  the  two  auriculo- 
ventricular,  the  aortic,  and  the  pulmonary.  These  rings  give 

FIG.  49. 


Pulm< 


cuspid  valve 


litral  valve 


DIAGRAM   OF   THE^RELATIVE    POSITION   OF   THE    VALVES   OF   THE    HEART, 
SEEN   FROM   ABOVE. 

A  is  placed  on  the  triangular  interval  where  the  fibrous  skeleton  is  the  thickest. 

attachment  by  their  external  circumference  to  the  muscular  fibres 
of  the  heart,  and  from  their  internal  circumference  send  fibrous 
prolongations  to  form  the  framework  of  the  several  valves.  The 
skeleton  is  strongest  just  in  the  triangular  interspace  between  the 
aortic  and  the  two  auriculo-ventricular  orifices  (letter  A  in  fig.  49). 
In  some  animals,  as  in  the  ox  and  the  elephant,  there  is  here  an 
irregularly  triangular  bone,  known  as  the  os  cordis. 

The  relative  position  of  these  rings  is  best  seen  by  removing 
the  auricles  and  the  great  vessels  at  the  base  of  the  heart — leaving 
the  several  valves3  and  looking  at  them  from  above,  as  shown  in 

P 


210  THE   HEART. 

the  diagram.  The  pulmonary  ring  is  on  the  highest  level,  and 
nearest  to  the  sternum  ;  below  it,  is  the  aortic  ring  lying  between 
and  in  front  of  the  auriculo-ventricular  rings,  which  are  on  the 
lowest  level. 

ATTACHMENT  OF  ^e  ^rous  rings  at  the  arterial  orifices  present 
THE  LARGE  AKTE-  three  festoons  with  their  concavities  directed  up- 
HIES  TO  THE  wards.  These  give  attachment,  above,  to  the 

middle  coat  of  the  artery ;  below,  to  the  muscular 
fibres  of  the  ventricles  ;  and,  internally,  to  the  fibrous  tissue  of  the 
valves.  The  vessels  are  also  connected  to  the  heart  by  the  serous 
layer  of  the  pericardium,  and  by  a  continuation  of  the  lining 
membrane  of  the  ventricle. 

This,  the  visceral   layer    of  the   pericardium, 

closely  invests  the  external  surface  of  the  heart, 
and  presents  the  usual  appearances  of  a  visceral  serous  membrane  : 
having  externally  a  layer  of  polygonal  epithelial  cells  which  rest 
upon  a  connective  tissue  layer,  intermingled  with  elastic  tissue. 
Beneath  this  layer  there  exists  the  subserous  areolar  tissue  stratum 
which  is  closely  connected  with  the  muscular  structure  of  the  heart 
(myocardium),  and  in  which  the  vessels,  nerves,  and  lymphatics 
lie  imbedded  in  more  or  less  fat. 

This    smooth  membrane  lining  the  cavities  of 

the  heart  resembles  the  visceral  layer  of  the  peri- 
cardium,  and  is  continuous  with  the  inner  coat  of  the  blood- 
vessels. It  may  be  easily  stripped  off,  and  is  thin  and  semi- 
transparent,  thicker  in  the  left  than  in  the  right  cavities,  thickest 
of  all  in  the  left  auricle.  It  consists  of  three  layers:  1,  a  layer 
of  flattened  polygonal  cells,  resting  upon,  2,  a  layer  of  con- 
nective tissue  in  which  are  some  elastic  fibres  resembling  the 
fenestrated  coat  of  an  artery;  and,  3,  a  thin  layer  of  connective 
tissue. 

The  muscular  fibres  of  the  heart  are  of  the  striped  variety, 
although  they  are  less  well  marked  and  regular  than  in  voluntary 
muscular  fibres :  the  striae  are  both  transverse  and  longitudinal. 
The  fibres  are  smaller  than  in  the  voluntary  kind,  have  a  well 
marked  single  nucleus,  are  branched,  and  are  destitute  of  sarco- 
lemma. 


MUSCULAR   FIBRES    OF   THE   HEART.  211 


ARRANGEMENT  '  ^^e  fibres  of  the  auricles  are  distinct  from  those 
OF  THE  MUSCULAR  of  the  ventricles.  They  consist  of  a  superficial 
FIBRES  OF  THE  layer  common  to  both  cavities,  and  a  deeper  layer 
proper  to  each.  The  superficial  fibres  run  trans- 
versely across  the  auricles,  and  are  most  marked  on  the  anterior 
surface;  some  pass  into  the  inter-auricular  septum.  Of  the  deeper 
fibres,  some  are  annular  and  surround  the  auricular  appendages  and 
the  entrance  of  the  great  veins,  upon  which  a  few  may  be  traced 
for  a  short  distance  ;  others,  looped,  run  over  the  auricles,  and  are 
attached  in  front  and  behind  to  the  auriculo-ventricular  rings. 

ARRANGEMENT  Speaking   generally,  it  may  be  said  that  the 

OF  THE  MUSCULAR  right  and  left  ventricles  of  the  heart  are  two 
FIBRES  OF  THE  conical  muscular  sacs,  enclosed  in  a  third,  which 
VENTRICLES.  not  orjv  enveiOpes  them,  but  is  reflected  into  the 

interior  of  both,  at  their  apices,  so  as  to  line  their  cavities.  All  the 
muscular  fibres  are  attached  by  one  end  to  the  fibrous  rings  of  the 
orifices,  and,  by  the  other  end,  after  a  more  or  less  spiral  course, 
they  reach  the  rings  again,  either  directly  or  through  the  medium 
of  the  chordae  tendineae  and  valves. 

The  external  or  superficial  fibres  pass  from  the  base,  where 
they  are  attached  to  the  auriculo-ventricular  rings,  to  the  apex. 
This  layer  is  thin  in  front,  but  behind  it  is  better  marked,  and 
here  the  fibres  do  not  pass  into  the  septum,  but  over  it,  while  in 
front,  they  pass  over  the  anterior  septum,  only  at  the  base  and  apex 
of  the  ventricle.  The  fibres  run  more  or  less  spirally  towards  the 
apex,  where  they  form  a  whorl  and  pass  into  the  left  ventricle,  so  as 
to  form,  in  part  the  innermost  vertical  muscular  layer,  in  part  the 
fleshy  columns  of  its  cavity.  The  superficial  anterior  fibres  pass 
backwards  to  the  left,  and  form,  behind,  the  posterior  papillary 
muscle  ;  and,  on  the  other  hand,  the  superficial  posterior  fibres  pass 
over  the  right  side  of  the  heart  and  constitute  the  anterior  papillary 
muscle. 

The  remaining  fibres  of  the  left  ventricle,  which  constitute 
its  chief  thickness,  are  attached  to  the  fibrous  rings  at  the  base  of 
the  heart.  They  pass,  more  or  less  obliquely,  in  the  posterior  and 
anterior  walls,  and  entering  the  lower  end  of  the  septum  pass  in 
three  different  directions  :  one  set,  upwards  in  the  septum  to  be 

p  2 


212  PECULIARITIES   OF   THE   POSTAL   CIRCULATION. 

attached  to  the  fibrous  tissue  in  the  triangular  interspace ;  a  second 
set  pass  through  the  septum  to  form  the  posterior  wall  of  the  right 
ventricle  and  its  posterior  papillary  muscle ;  while  the  third  set 
take  a  transverse  circular  course  in  the  left  ventricle,  some  of  its 
fibres  being  continuous  with  those  of  the  right  ventricle. 

The  fibres  of  the  right  ventricle  are  arranged  on  a  plan  similar 
to  that  of  the  left  ventricle,  of  which  it  may  be  considered  an 
appendage.  The  fibres,  which  correspond  to  those  forming  the 
chief  thickness  of  the  left  ventricle,  are  similarly  arranged  into  an 
anterior,  middle  and  posterior  set :  the  anterior  pass  backwards 
into  the  septum  to  reach  the  posterior  wall  of  the  left  ventricle 
and  interlace  in  the  septum  with  the  posterior  set  which  pass 
forwards  in  the  septum  to  the  front  wall  of  the  left  ventricle  ;  the 
middle  set  come  chiefly  from  the  outer  wall  of  the  right  ventricle, 
deep  down  at  the  lower  part  of  the  septum,  and  then  ascend  to  be 
attached  to  the  fibro-cartilage.  Besides  these  there  are  more  or 
less  numerous  annular  fibres  encircling  the  right  ventricle.1 

THICKNESS  OF  The  average  thickness  of  the  right  auricle  is 

THE  CAVITIES.  about  one  line ;  that  of  the  left,  one  and  a  half. 

The  average  thickness  of  the  right  ventricle  at  its  thickest  part — 
i.e.  the  base, —  is  about  two  lines.  That  of  the  left  ventricle  at  its 
thickest  part — i.e.  the  middle — is  about  half  an  inch.  In  the 
female  the  average  is  less. 

PECULIARITIES  The   heart    and    the  circulation    of  the   foetus 

OF  THE  FCETAL  differ  from  that  of  the  adult  in  the  following 
CIRCULATION.  points  : — 

1.  The  Eustachian  valve  is  well  developed  as  a  crescentic  fold 
which  guides  the  current  of  blood  from  the  inferior  vena  cava 
through  the  right  auricle  into  the  foramen  ovale. 

2.  The  foramen  ovale  is  widely  open  up  to  the  fourth  month,  after 
which  a  septum  grows  up  from  the  lower  border  of  the  left  side, 
so  that  at  the  sixth  month  the  blood  can  only  pass  in  the  onward 
direction  into  the  left  auricle. 

1  There  are  other  accounts  given  of  the  arrangements  of  the  muscular  struc- 
ture of  the  heart,  and  that  given  by  Pettigrew  is  one  which  is  adopted  .by  many  of 
the  best  anatomists.  For  further  information  on  this  subject  consult  Pettigrew, 
Philosoph.  Transactions,  1864  ;  Dr.  Sibson,  Medical  Anatomy,  1869  ;  Winckler, 
Mailer's  Archiv,  1865 ;  Quain's  Anatomy,  vol.  ii.  p.  495,  1882. 


FOETAL   CIKCULATION.  213 

3.  The  right  and  left  pulmonary  arteries  are  very  small  and  ill 
developed,  so  as  to  admit  very  little  blood  to  the  lungs. 

4.  The  ductus  arteriosus,  from  the  commencement  of  the  left 
pulmonary  artery  to  the  aorta,  is  widely  open. 

5.  The  liypocjastric  or  umbilical  arteries,  branches  of  the  anterior 
division  of  the  internal  iliac,  emerge  through  the  umbilicus  and  pass 
to  the  placenta,  so  that  the  impure  blood  may  be  oxygenated. 

6.  The  umbilical  vein  returns  the  pure  blood  partly  to  the  liver, 
and  partly  through  the 

7.  Ductus  venosus  into  the  inferior  vena  cava. 

8.  The  right  and  left  ventricles  are  of  equal  thickness,  because 
they  have  equal  work  to  perform. 


FCETAL   CIRCULATION. 

CIKCCLATION  OF  Arterial  blood  is  brought  from  the  placenta  by 
THE  BLOOD  IN  THE  the  umbilical  vein  (fig.  50),  and  enters  at  the  um- 
F(ETtTS-  bilicus,  whence  it  passes  to  the  under  surface  of 

the  liver.  Here  it  gives  off  some  branches  to  the  left  lobe,  and 
others  to  the  lobulus  Spigelii  and  lobulus  quadratus,  which  eventu- 
ally return  their  blood  into  the  inferior  vena  cava.  At  the  trans- 
verse fissure  it  divides  into  two  branches — one,  the  smaller,  termed 
the  ductus  venosus,  passes  straight  to  enter  into  the  inferior  vena 
cava,  having  previously  joined  the  left  hepatic  vein ;  the  other,  or 
right  division,  joins  the  vena  portse,  and,  after  ramifying  in  the 
right  lobe  of  the  liver,  returns  its  blood  through  the  hepatic  veins 
into  the  inferior  vena  cava. 

From  the  inferior  vena  cava,  which  thus  receives  its  blood 
from  three  sources,  the  blood  enters  the  right  auricle,  and  the 
stream  (directed  by  the  Eustachian  valve)  flows  through  the  fora- 
men ovale  into  the  left  auricle,  where  it  becomes  mingled  with  a 
little  blood,  which  is  returned  from  the  pulmonary  veins.  From 
the  left  auricle  it  runs  through  the  left  auriculo-ventricular  open- 
ing into  the  left  ventricle,  and  thence  through  the  aorta  into  the 
great  vessels  of  the  head  and  upper  extremities  (only  a  small 
quantity  passing  into  the  descending  thoracic  aorta),  which  are 


214 


FOETAL   CIRCULATION. 


thus  supplied  by  almost  pure  blood.  From  the  head  and  upper 
limbs,  the  blood  returns  (impure)  through  the  superior  vena  cava 
into  the  right  auricle,  whence,  mixed  with  a  small  quantity  derived 


FIG.  50. 


SUPR  V.  C 


FORAMEN  OVALE 


PLAC  ENTA 

SCHEME   OF   THE   FCETAL   CIECULATION. 


from  the  inferior  cava,  it  passes  into  the  right  ventricle.  From 
the  right  ventricle  the  blood  passes  through  the  pulmonary  artery 
and  the  ductus  arteriosus  into  the  commencement  of  the  descend- 


POSTAL    CIRCULATION.  215 

ing  aorta,  only  a  very  small  quantity  of  it  being  distributed  to  the 
lungs  ;  the  lungs  are  in  the  fetus  almost  solid  organs,  and  the  blood 
distributed  to  them  is  returned  by  the  pulmonary  veins  into  the 
left  auricle.  The  blood  which  passes  into  the  descending  aorta, 
through  the  ductus  arteriosus,  is  mingled  with  the  small  amount 
coming  through  the  arch,  and  is  then  conveyed  through  the  ab- 
dominal aorta  into  the  iliac  arteries  ;  part  is  transmitted  through 
the  umbilical  arteries  (branches  of  the  internal  iliac  arteries)  to  the 
placenta  to  become  re-oxygenated  ;  part  passes  into  the  lower 
extremities  through  the  external  iliac  and  femoral  arteries. 

CHANGES  IN  THH         The  following  changes  take  place  in  the  circu- 
CIKCULATION  AT         lation  after  birth  : l — 

BlRTH-  1.  The  umbilical  vein  becomes  obliterated  from 

the  second  to  the  fifth  day  after  birth,  and  subsequently  forms  the 
round  ligament  of  the  liver. 

2.  The  ductus  venosus  also   becomes   closed   about   the   same 
period,  and  may  be  traced  as  a  thickened  cord  in  the  fissure  of  the 
ductus  venosus. 

3.  The  foramen  ovale  becomes  closed  from  the  sixth  to  the 
tenth  day ;  but  not  infrequently  a  small  indirect  valvular  com- 
munication may  be  found  forming  a  communication  between  the 
two  auricles. 

4.  The  ductus  arteriosus  contracts  immediately  after  birth,  and 
becomes  closed  from  the  sixth  to  the  tenth  day.     It  eventually 
forms  a  fibrous  cord  connecting  the  left  pulmonary  artery  with  the 
aorta,  the  left  recurrent  laryngeal  nerve  winding  round  its  left 
border. 

5.  The  pulmonary  arteries  enlarge  and  convey  venous  blood  to 
the  lungs.     These  organs  during  foetal  life  receive  only  a  small 
quantity  of  blood  from  these  arteries. 

6.  The  liypofjasiric  arteries  become  obliterated  on  the  fourth  or 
fifth  day  after  birth. 

1  It  is  well  to  bear  in  mind  that  these  important  vascular  changes  do  not  take 
place  suddenly  at  birth,  but  that  they  are  the  result  of  a  gradual  development 
which  is  completed  at,  or  soon  after,  birth,  mainly  by  the  act  of  inspiration, 
whereby  the  blood  passes  through  the  lungs,  the  placental  circulation  at  the  same 
time  being  interrupted. 


216  THE    TRACHEA. 


STEUCTUEE   OF   THE  LUNGS. 

The  lungs  are  very  vascular  spongy  organs  in  which  the  blood 
is  oxygenated  by  exposure  to  atmospheric  air.  Their  situation  and 
shape  have  been  described  (p.  166).  We  must  now  examine  the 
trachea,  the  common  air-passage  to  both  lungs,  and  then  trace  this 
tube  downwards  to  its  bifurcation  into  the  two  bronchi,  which,  with 
their  minute  subdivisions,  form  the  main  structure  of  the  lungs. 

This    is    a   partly    cartilaginous,    partly   mem- 
TBACHEA.  ,  ,    ,  ,  f  °    .        '    J       ./,,     r 

branous  tube,  and  is  situated  in  the  middle  line. 

It  extends  from  the  cricoid  cartilage,  i.e.  opposite  the  upper 
border  of  the  sixth  cervical  vertebra,  to  the  third  dorsal  vertebra, 
where  it  divides  into  two  tubes,  the  right  and  left  bronchus  :  one 
for  each  lung.  Its  length  is  from  four  to  four  and  a  half  inches, 
and  its  width  from  eight  to  ten  lines  ;  but  these  measurements 
vary  according  to  the  age  and  sex  of  the  patient  and  the  capacity 
of  the  lungs.  The  trachea  is  surrounded  by  a  quantity  of  loose 
connective  tissue,  so  as  to  allow  of  its  free  mobility.  It  is  kept 
permanently  open  by  a  series  of  incomplete  cartilaginous  rings, 
from  sixteen  to  twenty  in  number,  which  extend  round  the  anterior 
two-thirds  of  its  circumference.  These  rings  are  deficient  at  the 
posterior  part  of  the  tube,  where  it  is  completed  by  a  fibro-muscular 
membrane.  This  deficiency  allows  the  trachea  to  enlarge  or 
diminish  its  calibre ;  and  for  this  purpose  the  membranous  part 
of  the  tube  is  provided  with  unstriped  muscular  fibres  which  can 
approximate  the  ends  of  the  rings. 

The  relations  of  the  trachea  to  the  surrounding  parts  should  be 
considered,  first,  in  the  neck,  and  then  within  the  thorax. 

In  the  neck,  kVhas,  in  front  of  it,  the  isthmus  of  the  thyroid  body, 
the  sterno-hyoid  and  sterno-thyroid  muscles,  the  inferior  thyroid 
veins,  two  layers  of  the  deep  cervical  fascia,  the  arteria  thyroidea 
ima,  if  present,  and  (at  the  root  of  the  neck)  the  innominate  and 
left  common  carotid  arteries.  Laterally,  it  is  in  relation  with  the 
lobes  of  the  thyroid  body,  the  common  carotid  arteries,  the  recur- 
rent laryngeal  nerves,  and  the  inferior  thyroid  arteries.  Behind  it, 
is  the  oesophagus,  inclining  slightly  to  the  left. 


THE   TRACHEA.  217 

In  the  chest,  the  trachea  is  contained  in  the  superior  media- 
stinum, and  has,  in  front  of  it,  the  manubrium  sterni,  the  origins  of 
the  sterno-hyoid  and  thyroid  muscles,  the  left  brachio-cephalic  vein, 
the  first  parts  of  the  innominate  and  left  common  carotid  arteries, 
the  transverse  portion  of  the  arch  of  the  aorta,  and  the  deep  cardiac 
plexus.  On  the  right  side  are  the  pleura  and  right  pneumogastric 
nerve  ;  on  the  left,  the  pleura,  the  left  carotid,  the  left  pneumo- 
gastric, cardiac,  and  recurrent  laryngeal  nerves. 

BRONCHI,  EIGHT         The  two  bronchi  differ  in  length,  direction,  and 
AND  LEFT.  diameter.     The  right,  wider  but  shorter  than  the 

left,  is  about  an  inch  long,  and  passes  more  horizontally  to  the 
root  of  its  lung,  on  a  level  with  the  fourth  dorsal  vertebra.  It  is 
larger  in  all  its  diameters  than  the  left ;  hence,  foreign  bodies 
which  have  accidentally  dropped  into  the  trachea  are  more  likely 
to  be  carried  into  the  right  bronchus  by  the  current  of  the  air. 
The  vena  azygos  major  arches  over  the  right  bronchus  to  terminate 
in  the  superior  vena  cava.  The  left  is  about  two  inches  in  length, 
and,  descending  more  obliquely  to  its  lung  than  the  right,  enters 
it  on  a  level  with  the  fifth  dorsal  vertebra.  The  left  bronchus 
passes  under  the  arch  of  the  aorta,  in  front  of  the  oesophagus  and 
the  thoracic  duct,  and  subsequently  crosses  in  front  of  the  descend- 
ing aorta. 

The  cartilages  of  the  trachea  vary  in  number  from  sixteen  to 
twenty,  of  the  right  bronchus  from  six  to  eight,  and  of  the  left 
from  nine  to  twelve.  Those  of  the  trachea  form  about  two-thirds 
of  a  circle,  somewhat  like  a  horseshoe  in  shape,  are  about  -\  th  of  an 
inch  in  their  vertical  direction,  and  -^th  in  thickness,  and  thicker 
in  the  middle  than  at  the  upper  and  lower  borders.  The  cartilages 
are  connected  and  covered  on  their  outer  and  inner  surfaces  by  a 
tough  membrane,  consisting  of  connective  and  elastic  tissues.  This 
membrane  is  attached  above  to  the  circumference  of  the  cricoid 
cartilage,  and  is  continued  through  the  whole  extent  of  the  trachea 
and  bronchial  tubes.  Posteriorly,  where  the  cartilages  are 'defi- 
cient, it  completes  the  integrity  of  the  air  tube.  In  this  tissue, 
which  is  of  a  pale  reddish  colour,  is  a  layer  of  unstriped  muscular 
fibres,  arranged  in  a  transverse  and  a  longitudinal  direction. 

The  first  cartilage  is  the  broadest,  and  is  frequently  divided  at 


218  THE   TRACHEA. 

one  end;  the  last  cartilage  is  placed  at  the  bifurcation  of  the 
trachea,  and  is  shaped  like  the  letter  y  ;  its  angle  projects  into 
the  centre  of  the  main  tube,  and  its  sides  belong  one  to  each 
bronchus. 

MUSCULAB  This  thin  stratum  of  unstriped  muscular  fibres 

FIBRES,  consists  of  two  layers,  and  is  brought  into  view 

when  the  fibrous  membrane  and  tracheal  glands  have  been  removed. 
The  longitudinal  fibres  are  the  more  external,  and  are  attached  by 
minute  tendons  to  the  extremities  of  the  cartilages ;  the  trans- 
verse fibres  (trachealis  muscle)  extend  transversely  between  the 
posterior  free  ends  of  the  cartilages.  By  their  contraction  they 
approximate  the  ends  of  the  cartilages  and  diminish  the  calibre  of 
the  trachea. 

This  lines  the  whole  tube,  but  is  most  abundant 

at  the  posterior  or  membranous  part  of  the  trachea, 

and  its  fibres  run  in  a  longitudinal  direction.    It  is  this  layer  which 

raises  the  mucous  membrane  into  folds,  and  its  elasticity  admits  of 

the  elongation  and  the  recoil  of  the  tube. 

TRACHEAL  Upon  the  outer  surface  of  the  fibrous  layer  of 

GLANDS.  the  trachea  are  a  number  of  small  mucous  glands, 

most  numerous  on  the  posterior  part  of  the  tube.  They  are  com- 
pound racemose  glands  lined  with  columnar  epithelium,  and  their 
excretory  ducts  pierce  the  fibrous  and  muscular  layers,  and  termi- 
nate on  the  free  surface  of  the  mucous  membrane.  In  health  their 
secretion  is  clear,  and  just  sufficient  to  lubricate  the  air-passages. 
In  bronchitis  they  are  the  sources  of  the  abundant  viscid 
expectoration. 

Mucous  MEM-  The  mucous  membrane  lining  the  air-passages 

BBANE.  is  a  continuation  of  that  of  the  larynx.    Its  colour 

in  the  natural  state  is  nearly  white,  but  in  catarrhal  affections  it 
becomes  bright  red,  in  consequence  of  the  accumulation  of  blood 
in  the  capillary  vessels.  It  is  continued  into  the  ultimate  air-cells, 
where  it  becomes  thinner  and  more  transparent.  In  its  deeper 
layer  is  found  a  considerable  amount  of  elastic  tissue ;  in  its  super- 
ficial layer  a  quantity  of  lymphoid  tissue.  Its  surface  is  lined 
with  a  layer  of  columnar  ciliated  epithelial  cells.  The  vibratile 
movement  of  the  cilia  is  directed  in  such  a  way  as  to  favour  the 


STRUCTURE  OF  THE  LUNGS.  219 

expectoration  of  the  mucus.  The  ciliated  epithelium  lining  the 
mucous  membrane  ceases  at  the  commencement  of  the  air-cells, 
where  it  is  replaced  by  the  squamous  variety. 

At  the  root  of  the  lung  each  bronchus  divides  into  two  branches, 
an  upper  and  a  lower,  corresponding  to  the  lobes  of  the  lung ;  on 
the  right  side,  the  lower  branch  sends  a  small  division  to  the  third 
lobe  of  the  lung.  The  tubes  diverge  through  the  lung,  and  divide 
into  branches,  successively  smaller  and  smaller,  until  they  lead  to 
the  air-cells.  These  ramifications  do  not  communicate  with  each 
other ;  hence,  when  a  bronchial  tube  is  obstructed,  all  supply  of 
air  is  cut  off  from  those  cells  to  which  it  leads. 

The  several  tissues — cartilaginous,  fibrous,  muscular,  mucous, 
and  glandular — which  compose  the  air-passages,  are  not  present  in 
equal  proportions  throughout  all  their  ramifications,  but  each  is 
placed  in  greater  or  less  amount  where  it  is  required.  The  car- 
tilaginous rings  necessary  to  keep  the  larger  tubes  permanently 
open  become,  in  the  smaller  tubes,  fewer  and  less  regular  in  form. 
As  the  subdivisions  of  the  tubes  multiply,  the  cartilages  consist  of 
small  pieces  placed  here  and  there  ;  they  become  less  and  less  firm, 
and  finally  disappear  when  the  tube  is  reduced  to  one-fortieth  of 
an  inch  in  diameter.  The  smallest  air-passages  are  entirely  mem- 
branous, being  formed  of  fibrous,  elastic,  and  muscular  tissues. 

The  lungs  are  two  in  number,  and  occupy  the 

lateral  cavities  of  the  chest.     Each  is  conical  in 

shape,  its  apex  extending  into  the  neck,  the  base  resting  ©n  the 

upper  or  convex  surface  of  the  diaphragm.     The  lung  presents  for 

examination — an  apex,  a  base,  two  surfaces,  and  two  borders. 

The  apex  extends  upwards  about  an  inch  and  a  half  above  the 
first  rib,  and  is  generally  marked  by  a  slight  groove  for  the  sub- 
clavian  artery.  The  lose  is  concave,  and  slopes  downwards  at  its 
posterior  part.  Its  outer  surface,  in  contact  with  the  chest  wall,  is 
smooth  and  convex,  and  is  deeper  behind  than  in  front.  Its  inner 
surface  is  concave,  and  hollowed  out  to  accommodate  the  heart  and 
its  large  vessels.  Its  anterior  border  is  sharp  and  overlaps  the 
large  vessels  and  the  pericardium.  The  posterior  border  is  rounded 
and  rests  in  the  broad  groove  on  the  side  of  the  bodies  of  the  dorsal 
vertebrae.  On  the  inner  concave  surface,  a  little  above  the  middle 


220  STRUCTURE   OF   THE   LUNGS. 

and  nearer  the  posterior  than  the  anterior  border,  is  the  root,  where 
the  large  vessels  and  bronchi  pass  to  and  from  the  lungs. 

Each  lung  is  traversed  on  its  external  surface  by  an  oblique 
fissure  which  passes  deeply  into  its  interior.  It  extends  from  the 
upper  part  of  the  posterior  border,  downwards  and  forwards  to  the 
anterior  border,  and  on  the  right  side  there  is  a  second  fissure 
passing,  forwards  and  upwards  from  the  oblique  fissure,  to  the  middle 
of  the  anterior  margin.  The  left  lung  presents  a  deep  notch  in 
the  anterior  border  in  which  the  pericardium  is  seen  as  far  as  the 
apex  of  the  heart. 

CONTBACTIBI-  When  an  opening  is  made  into  the  chest,  the 

LITY  OF  THK  l1111^  which  was  in  contact  with  the  ribs,  imme- 

LcNO>  diately  recedes  from'  them,  and,  provided  there 

be  no  adhesions,  gradually  contracts.  If  the  lungs  be  artificially 
inflated,  either  in  or  out  of  the  chest,  we  observe  that  they  sponta- 
neously expel  a  part  of  the  air.  This  disposition  to  contract,  in 
the  living  and  the  dead  lung,  is  due  to  the  elastic  tissue  in  the 
bronchial  tubes  and  the  air-cells ;  but  more  especially  to  a  layer  of 
delicate  elastic  tissue  on  the  surface  of  the  lung,  which  has  been 
described  by  some  anatomists  as  a  distinct  coat,  under  the  name  of 
the  second  or  inner  layer  of  the  pleura.1 

The  lungs  are  of  a  livid  red  or  violet  colour ; 
they  often  present  a  mixture  of  tints,  giving  them 
a  marble-like  appearance.  This  is  not  the  natural  colour  of  the 
organ,  since  it  is  produced  in  the  act  of  dying.  It  depends  upon 
the  stagnation  of  the  venous  blood,  which  the  right  ventricle  still 
propels  into  the  lungs,  though  respiration  is  failing.  The  tint 
varies  in  particular  situations  in  proportion  to  the  amount  of  blood, 
and  is  always  deepest  at  the  back  of  the  lung.  But  the  colour  of 
the  proper  tissue  of  the  lung,  apart  from  the  blood  which  it  con- 
tains, is  pale  and  light  grey.  This  colour  is  seldom  seen  except  in 
the  lungs  of  infants  who  have  never  breathed,  or  after  death  from 
profuse  haemorrhage. 

Upon  or  near  the  surface  of  the  lungs,  numerous  dark  spots 
are  observed  which  do  not  depend  upon  the  blood,  since  they  are 

1  In  some  animals,  the  seal  especially,  the  elasticity  of  this  tissue  is  very 
strongly  marked. 


STRUCTURE  OF  THE  LUNGS.  221 

seen  in  the  palest  lungs.  They  vary  in  number  and  size,  and  in- 
crease with  age.  The  source  of  these  discolorations  is  not  exactly 
known ;  but  they  are  probably  deposits  of  minute  particles  of  car- 
bonaceous matter  which  have  been  inhaled  with  the  air. 

The  lungs  are  composed  of  cartilaginous  and  membranous  tubes, 
of  which  the  successive  subdivisions  convey  the  air  into  closely- 
packed  minute  cells,  called  the  air-vesicles ;  of  the  ramifications  of 
the  pulmonary  artery  and  veins ;  of  the  bronchial  vessels  concerned 
in  their  nutrition ;  of  lymphatics  and  nerves.  These  component 
parts  are  united  by  connective  tissue,  and  covered  externally  by 
pleura.  The  part  at  which  they  respectively  pass  in  and  out  is 
called  the  root  of  the  lung. 

The  lungs  are  the  lightest  organs  in  the  body,  and  float  in 
water,  their  specific  gravity  varying  from  '345  to  '746.  When 
entirely  deprived  of  air  they  sink.  This  is  observed  in  certain 
pathological  conditions  ;  e.g.  when  one  lung  is  compressed  by  effu- 
sion into  the  chest,  or  rendered  solid  by  inflammation. 

In  the  male  the  average  weight  of  the  right  lung  is  22  oz.,  that 
of  the  left  20  oz. ;  in  the  female  the  average  is  about  17  oz.  on  the 
right,  and  15  oz.  on  the  left  side. 

The  total  capacity  of  the  lungs  in  an  adult  male  of  ordinary 
height  is  282  cubic  inches ;  and  the  amount  of  air  still  contained 
in  the  lungs  after  a  forced  expiration  has  been  estimated  at  57  cubic 
inches.  The  difference  between  these  volumes — viz.  225  cubic 
inches — indicates  the  amount  of  air  which  can  be  inhaled,  from 
the  deepest  expiration  to  the  fullest  inspiration,  and  has  been 
termed  the  vital  capacity  of  the  lungs.1 

The  surface  of  the  lung  is  closely  invested  by  a  thin  transpa- 
rent layer  of  serous  membrane,  immediately  beneath  which  is  a  fine 
areolar  tissue,  called  subserous,  which  is  very  soft  and  elastic  so  as  to 
allow  of  the  free  expansion  of  the  organ.  This  tissue  sends  inwards 
prolongations,  called  interlobular,  which  map  out  the  lungs  into  a 
number  of  angular  spaces  of  various  sizes  termed  lobules :  those  on 
the  surface,  indicated  by  faint  white  lines,  are  larger  than  those  in 
the  interior  of  the  lung.  Each  lobule  is  a  lung  in  miniature,  and 
consists  of  a  small  bronchial  tube  and  its  termination  in  dilated 
1  Hutchinson,  Med.  Chir.  Trans.,  vol.  xxix.,  1846. 


222 


STRUCTURE   OF   THE   LUNGS. 


FIG.  61. 


extremities,  called  infundibula,  of  ramifications  of  the  pulmonary 
vessels,  lymphatics,  and  nerves,  and,  lastly,  of  the  bronchial  vessels. 
The  cells  of  the  interlobular  tissue  have  no  communication  with 
the  air-vesicles,  unless  the  latter  be  ruptured  by  excessive  straining, 
and  then  this  connective  tissue  becomes  inflated  with  air  and  is 
called  interlobular  emphysema.  When  infiltrated  with  serum  it 
constitutes  oedema  of  the  lung. 

Each  bronchial  tube  divides  and  subdivides  into  smaller  and 
smaller    divergent  tubes,  until  each  has  reached  a  reduced  size 

of  about  1  mm. ;  it  then  enters  a  pul- 
monary lobule,  when  it  is  termed  a 
lobular  bronchial  tube,  and  presents  on 
its  walls  numerous  dilatations,  called 
air-cells  or  alveoli,  which  vary  from 
-^  to  -^  of  an  inch  in  diameter  (fig. 
51).  Thus  reduced  fin  size,  the  walls 
of  the  tubes  no  longer  present  traces 
of  cartilaginous  tissue,  but  are  com- 
posed of  a  delicate  elastic  membrane 
upon  which  the  capillaries  ramify  in 
a  very  minute  network.1  Each  tube 
finally  terminates  in  an  enlarged  ir- 
regular passage  —  alveolar  passage — 
from  which  proceed  on  all  sides  nume- 
rous blind  dilatations,  named  infundi- 
bula. 

The    smaller  bronchial    tubes    are 

encircled  by  more  or  less  complete  rings  of  cartilage ;  but  as  the 
tubes  lessen  in  calibre,  the  rings  become  less  perfect ;  so  that  when 
the  tubes  are  reduced  to  ^th  of  an  inch  in  diameter  the  rings 
entirely  disappear.  The  continuation  of  the  air-tubes  consists 
simply -of  fibrous  tissue  which  becomes  gradually  thinner,  so  that 
in  the  smallest  tubes  they  are  reduced  to  simply  membranous 
tubes,  and  are  continued  on  as  irregular  passages — intercellular 

1  In  phthisis  the  expectoration  contains  some  of  the  dtbris  of  this  elastic 
framework  of  the  air-vesicles  ;  it  can  be  seen  under  the  microscope,  and  is  a  test  of 
the  character  of  the  sputa. 


ULTIMATE  AIR-CELLS  OF  THE  LUNG 
(FROM  KSLLIKER).  MAGNIFIED 
TWENTY-FIVE  TIMES. 


STRUCTURE  OF  THE  LUNGS.  223 

passages  l — which  are  studded  with  numerous  small  saccules  termed 
air-cells  or  alveoli. 

The  air-cells  are  small,  shallow,  polyhedral  depressions,  from 
^th  to  --fro-th  of  an  inch  in  diameter,  separated  by  thin  partitions 
or  septa  which  communicate  freely  with  the  intercellular  passages, 
but  not  with  each  other.2 

The  mucous  membrane  which  invests  the  divisions  of  the  bronchi 
as  far  as  the  intercellular  passages  is  lined  with  epithelium  of  the 
columnar  ciliated  variety.  At  this  situation  the  character  of  the 
epithelium  changes  to  that  of  a  squamous  kind  consisting  of  a 
single  layer  of  flat  polygonal  nucleated  cells. 

The  structure  of  the  air-cells  differs  in  some  important  features 
from  that  of  the  smaller  bronchial  tubes  ;  the  muscular  tissue  dis- 
appears, the  elastic  tissue  is  no  longer  arranged  in  bundles,  but 
becomes  frayed  out  and  intermingled  with  the  connective  tissue. 

PULMONARY  The  pulmonary  artery  conveying  venous  blood 

VESSELS.  to   the   lungs    divides    and    subdivides   with   the 

bronchial  tubes,  and  terminates  in  a  fine  dense  capillary  plexus  on 
the  walls  of  the  intercellular  passages  and  air  cells,  beneath  the 
epithelium.  These  plexuses — the  pulmonary  capillaries — form  a 
single  layer  of  capillaries  which  is  so  close  that  the  interstices  are 
even  narrower  than  the  blood-vessels,  which  average  about  -3  0*0  0 
of  an  inch  in  diameter.  The  plexus  which  ramifies  over  the  air  cell 
does  not  communicate  with  the  plexus  covering  another  air  cell. 
The  blood  and  air  are  not  in  actual  contact.  Nothing,  however, 
intervenes  but  the  wall  of  the  cell  and  the  capillary  vessels,  which 
are  such  delicate  structures  that  they  oppose  no  obstacle  to  the  free 
interchange  of  gases  by  which  the  blood  is  purified.  This  purifi- 
cation is  effected  by  the  taking  in  of  oxygen,  and  the  elimination 
of  carbonic  acid  and  watery  vapour.  The  most  complete  purifica- 
tion takes  place  in  the  single  layer  of  capillaries  between  the  folds 
of  membrane  projecting  into  the  cell ;  for  in  this  situation  both 
sides  of  these  vessels  are  exposed  to  the  action  of  the  air.  The 
blood,  circulating  in  steady  streams  through  this  capillary  plexus, 

1  Kainey,  Med.  Chir.  Trans.,  vol.  xxviii.,  1845. 

2  The  structure  of  the  minute  air-cells  of  the  human  lung  is  in  all  respects 
similar  to  the  large  respiratory  sac  of  the  reptile. 


224  DISSECTION   OF   THE   PHARYNX. 

returns  through  the  pulmonary  veins.  These,  at  first  extremely- 
minute,  gradually  coalesce  into  larger  and  larger  branches  which 
anastomose  very  freely,  and  accompany  the  arteries.  They  finally 
emerge  from  the  root  of  the  lung  by  two  large  trunks  which  carry 
the  oxygenated  blood  to  the  left  auricle  of  the  heart.  The  pul- 
monary veins  are  not  provided  with  valves. 

'   BRONCHIAL  These  small  arteries,  two  or  more  in  number, 

ARTERIES.  are  the  nutrient  vessels  of  the  lungs.     The  right 

arises  either  from  the  first  aortic  intercostal,  or,  conjointly  with 
the  left  bronchial,  from  the  thoracic  aorta.  The  left,  usually  two 
in  number,  come  from  the  thoracic  aorta.  .They  enter  the  lung 
behind  the  divisions  of  the  bronchi,  which  they  accompany.  The 
bronchial  vessels  are  distributed  in  various  ways  :  some  of  their 
branches  supply  the  coats  of  the  air-passages,  the  large  blood- 
vessels and  the  lymphatic  glands ;  others  the  interlobular  tissue  : 
a  few  reach  the  surface  of  the  lung,  and  ramify  beneath  the  pleura. 
The  right  bronchial  veins  terminate  in  the  vena  azygos ;  the  left, 
in  the  superior  intercostal  vein. 

The  nerves  of  the  lung  are  derived  from  the  pneumogastric  and 
the  sympathetic.  They  enter  with  the  bronchial  tubes,  forming  a 
plexus  in  front  and  behind  them,  anterior  and  posterior  pulmonary 
plexus,  in  which  are  found  minute  ganglia. 

The  lymphatics  of  the  lungs  consist  of  a  superficial  and  deep 
set :  some  commence  in  the  lymphatic  capillaries  in  the  inter- 
lobular tissue,  and  thence  pass  to  the  surface,  forming  a  network 
which  communicates  with  the  subpleural  lymphatic  plexus ;  others 
take  their  origin  in  the  mucous  membrane  of  the  bronchial  tubes  ; 
and  all  eventually  enter  the  bronchial  glands.  Of  these,  the  larger 
are  situated  about  the  bronchi  near  the  root  of  the  lung,  parti- 
cularly under  the  bifurcation  of  the  trachea. 


DISSECTION  OF  THE    PHAEYNX. 


To  obtain  a  view  of  the  pharynx,  cut  through 

the  trachea,  the  oesophagus,  the  large  vessels  and 

nerves  of  the  neck,  a  short  distance  above  the  first  rib,  and  then 


THE    PHARYNX.  225 

'separate  them  from  the  prevertebral  muscles  which  lie  immediately 
in  front  of  the  bodies  of  the  cervical  vertebras,  and  to  which  they 
are  but  loosely  connected.  The  sawn  surface  of  the  skull  should 
now  be  allowed  to  rest  horizontally  upon  the  table,  and  the  base 
should  then  be  sawn  or  chiselled  through  transversely  between  the 
vertebral  column  and  the  styloid  processes  of  the  temporal  bone.  It 
is  not  always  easy  to  keep  the  saw  so  well  behind  the  pharynx  and 
the  vessels  and  nerves  as  to  detach  them  without  injury,  in  which 
case  it  is  well  to  use  the  chisel  in  preference.  When  this  is  accom- 
plished the  student  will  find  that  the  pharynx  and  larynx  are  left 
attached  to  the  anterior  half  of  the  section;  the  spinal  column 
and  the  prevertebral  muscles  to  the  posterior  half.  Tow  should 
then  be  introduced  through  the  mouth  and  oesophagus  to  distend 
the  walls  of  the  pharynx.  The  front  section  is  now  to  be  fastened 
to  a  block  by  means  of  hooks,  so  that  the  pharyngeal  muscles  are 
towards  the  dissector,  and  the  oesophagus  downwards. 

One  side  of  the  pharynx  should  be  dissected  to  show  the  con- 
strictor muscles,  the  other  should  be  reserved  for  the  vessels  and 
nerves  in  immediate  relation  with  the  pharynx. 

GENERAL  DE-  ^ne  term  pharynx  is  applied  to  that  part  of  the 

SCRIPTION  OF  alimentary  canal  which  receives  the  food  after  it 

PHARYNX.  ^as  been  masticated,  and  propels  it  downwards 

into  the  ossophagus.  It  is  a  funnel-shaped  muscula  rbag,  about 
four  and  a  half  inches  in  length,  and  broader  in  its  transverse  than 
in  its  antero-posterior  diameter.  Its  broadest  portion  is  situated 
opposite  the  os  hyoides,  and  it  then  gradually  tapers  as  far  as  the 
cricoid  cartilage,  where  it  is  continuous  with  the  oesophagus,  which 
is  its  narrowest  portion.  Its  upper  part  is  attached  to  the  basi- 
lar  process  of  the  occipital  bone  and  the  petrous  portions  of  the 
temporal  bones ;  behind,  it  is  loosely  connected  by  deep  cervical 
fascia  with  the  prevertebral  muscles ; l  in  front,  it  is  attached 
to  the  internal  pterygoid  plates  and  hamular  processes  of  the 
sphenoid,  to  the  pterygo-maxillary  ligaments,  the  lower  jaw,  the 
tongue,  the  hyoid  bone,  and  the  stylo-hyoid  ligaments,  and  to  the 
thyroid  and  cricoid  cartilages;  laterally,  it  is  loosely  connected 

1  It  is  in  this  tissue  (which  never  contains  fat)  that  post-pharyngeal  abscesses 
are  seated. 


226  THE    PHARYNX. 

to  the  styloid  muscles,  and  it  has  in  close  relation  with  it,  the 
common  and  internal  carotid  arteries,  the  glosso-pharyngeal, 
pneumogastric,  spinal  accessory,  hypoglossal  and  sympathetic 
nerves ;  the  internal  pterygoid,  tensor  palati  and  stylo-pharyngeus 
muscles ;  the  lingual  and  ascending  pharyngeal  arteries,  the 
superior  laryngeal  and  external  laryngeal  nerves,  the  ascending 
palatine  artery,  and  the  internal  jugular  vein.  Its  dimensions  are 
not  equal  throughout.  Its  breadth  at  the  upper  part  is  equal  to 
that  of  the  posterior  openings  of  the  nose  :  here  it  is  only  required 
to  convey  air,  but  it  becomes  much  wider  in  the  situation  where 
it  transmits  the  food — that  is,  at  the  back  of  the  mouth  ;  thence  it 
gradually  contracts  to  the  oesophagus.  The  pharynx,  therefore, 
may  be  compared  to  a  funnel  communicating  in  front  by  wide 
apertures  with  the  nose,  the  mouth,  and  the  larynx;  while  the 
oesophagus  represents  the  tube  leading  from  its  lower  end.  The 
upper  part  of  the  funnel  forms  a  cul-de-sac  at  the  basilar  process 
of  the  occipital  bone.  At  this  part  there  is,  on  each  side,  the 
opening  of  a  narrow  canal,  called  the  Eustachian  tube,  through 
which  air  passes  to  the  tympanum  of  the  ear.1 

Before  the  muscles  of  the  pharynx  can  be  examined,  we  must 
remove  a  layer  of  thin  fascia,  termed  the  pharyngeal  fascia.  It 
is  the  layer  of  deep  cervical  fascia  behind  the  pharynx,  and  must 
not  be  confounded  with  the  proper  pharyngeal  aponeurosis,  which 
intervenes  between  its  muscular  and  mucous  walls. 

At  the  back  of  the  pharynx,  near  the  base  of  the  skull,  are 
a  few  lymphatic  glands.  They  sometimes  enlarge,  and  form  a, 
perceptible  tumour  in  the  pharynx. 

In  removing  the  fascia  from  the  pharyngeal  muscles,  notice 

1  Observe  that  the  pharynx  conducts  to  the  oesophagus  by  a  gradual  contraction 
of  its  channel.  This  transition,  however,  is  in  some  cases  sufficiently  abrupt  to. 
detain  a  foreign  body,  such  as  a  morsel  of  food  more  bulky  than  usual,  at  the  top 
of  the  oesophagus.  If  such  a  substance  become  firmly  impacted  in  this  situation, 
one  can  readily  understand  that  it  will  not  only  prevent  the  descent  of  food  into 
the  stomach,  but  that  it  may  occasion,  by  its  pressure  on  the  trachea,  alarming 
symptoms  of  suffocation.  Supposing  that  the  obstacle  can  neither  be  removed  by 
the  forceps,  nor  pushed  into  the  stomach  by  the  probang,  it  may  then  become 
necessary  to  extract  it  by  making  an  incision  into  the  oesophagus  on  the  left  side 
of  the  neck. 


CONSTRICTOR   MUSCLES   OF   THE    PHARYNX. 


227 


PHARYNX. 


that  a  number  of  veins  ramify  and  communicate  in  all  directions. 
They  constitute  the  pharyngeal  venous  plexus,  and  terminate  in 
the  internal  jugular  veins. 

CONSTRICTOR  They  are  three  in  number,  and  arranged  so  that 

MUSCLES  OF  THE        they  overlap  each  other — i.e.  the  inferior  overlaps 
the  middle,  and  the  middle  the  superior  (fig.  52). 

FIG.  52. 


J\J>       Tensor  palati. 

Levator  palati. 


Orbicularis  oris  .    . 

Pterygo-maxillary  ) 
ligament     .    .    j 


Mylo-hyoideus   . 

Os  hyoides      .    . 
Thyro-hyoid  liga- 
ment .... 

Pomum  Adami  . 


Cricoid  cartilage 
Trachea      .    . 


.Glosso-pbaryngeal  n. 
Stylo-pharyngeus. 


Superior  laryngeal 
u.  and  a. 


External  laryngeal  r. 
-    Crico-thyroideus. 

Inferior  laryngeal  n. 
(Esophagus. 


SIDE    VIEW   OF    THE    MUSCLES    OF    THE    PHABYNX. 

They  have  the  same  attachments  on  both  sides  of  the  body ;  and 
the  fibres  from  the  right  and  left  meet  together,  and  are  inserted 

Q  2 


228  CONSTRICTOR  MUSCLES    OF   THE   PHARYNX. 

in  the  mesial  line,  the  insertion  being  marked  by  a  white  longitu- 
dinal line,  called  the  raphe. 

The  inferior  constrictor,  the  most  superficial  and  thickest  of  the 
thin  constrictors,  arises  from  the  side  of  the  cricoid  cartilage 
behind  the  crico-thyroid  muscle,  from  the  surface  behind  the 
oblique  ridge  and  the  lower  cornu  of  the  thyroid  cartilage.  Its 
fibres  expand  over  the  lower  part  of  the  pharynx.  The  superior 
fibres  ascend ;  the  middle  run  transversely ;  the  inferior  descend 
slightly,  and  are  inserted  into  the  posterior  median  raphe.  The 
lower  fibres  are  continuous  with  those  of  the  oesophagus.  Beneath 
its  lower  border  the  recurrent  laryngeal  nerve  enters  the  larynx. 
Its  nerve-supply  is  from  the  pharyngeal  plexus,  the  external 
laryngeal  and  the  recurrent  laryngeal  nerves. 

In  order  to  completely  expose  the  next  muscle,  the  right  half 
of  the  inferior  constrictor  should  be  reflected  from  the  middle  line. 

The  middle  constrictor  arises  from  the  upper  edge  of  the  greater 
cornu  of  the  os  hyoides,  from  its  lesser  cornu,  and  part  of  the  stylo- 
hyoid  ligament,  and  is  inserted  into  the  posterior  median  raphe. 
Its  fibres  take  different  directions,  so  that,  with  those  of  the 
opposite  muscle,  they  form  a  lozenge.  The  lower  angle  of  the 
lozenge  is  covered  by  the  inferior  constrictor;  the  upper  angle 
ascends  nearly  to  the  basilar  process  of  the  occipital  bone,  and 
terminates  upon  the  pharyngeal  aponeurosis.  The  external  surface 
of  the  muscle  is  covered  at  its  origin  by  the  hyo-glossus,  from 
which  it  is  separated  by  the  lingual  artery ;  while  beneath  it  are 
the  superior  constrictor,  the  stylo-pharyngeus,  and  palato-pharyn- 
geus  muscles  and  the  pharyngeal  aponeurosis.  Its  nerve  comes 
from  the  pharyngeal  plexus. 

Between  the  middle  and  inferior  constrictors,  the  superior 
laryngeal  artery  and  nerve  perforate  the  thyro-hyoid  membrane 
to  supply  the  larynx. 

The  superior  constrictor  consists  of  pale  muscular  fibres,  and 
arises  from  the  hamular  process  of  the  sphenoid  bone,  and  from  the 
lower  part  of  its  internal  pterygoid  plate ;  from  the  tuberosity  of 
the  palate  bone  and  the  reflected  tendon  of  the  tensor  palati  ; 
from  the  pterygo-maxillary  ligament  (which  connects  it  with  the 
buccinator)  ;  from  the  back  part  of  the  ruylo-hyoid  ridge  of  the 
lower  jaw,  and  from  the  side  of  the  tongue.  The  fibres  pass  back- 


CONSTRICTOR   MUSCLES   OF   THE   PHARYNX. 


229 


wards  to  the  mesial  raphe  :  some  of  them  are  inserted  through  the 
medium  of  the  pharyngeal  aponeurosis  into  the  basil ar  process. 
Its  nerve  comes  from  the  pharyngeal  plexus. 

The  upper  border  of  the  superior  constrictor  presents,  on  either 
side,  a  free  semilunar  edge  with  its  concavity  upwards,  so  that, 

FIG.  53. 


VIEW    OF   THE  CONSTRICTOR   MUSCLES    FROM    BEHIND. 

between  it  and  the  base  of  the  skull,  a  space  is  left  in  which  the 
muscle  is  deficient  (fig.  53).  Here  the  pharynx  is  strengthened 
and  walled  in  by  its  own  aponeurosis.  The  space  is  called  the 
sinus  of  Morgagni ;  and  in  it,  with  a  little  dissection,  we  expose 
the  muscles  which  raise  and  tighten  the  soft  palate:  i.e.  the  levator 
palati  and  the  tensor  palati.  The  Eustachian  tube  opens  into  the 


230  OPENINGS    INTO    THE    PHARYNX. 

pharynx  just  here.  The  fibres  of  the  stylo-pharyngeus  pass  in 
between  the  superior  and  middle  constrictors,  and  expand  upon  the 
side  of  the  pharynx  ;  some  of  them  mingle  with  those  of  the  con- 
strictors, so  as  to  be  able  to  lift  up  the  pharynx  in  deglutition ;  but 
most  of  them  are  inserted  into  the  superior  and  posterior  margins 
of  the  thyroid  cartilage. 

PHARYNGEAL  The  pharyngeal  aponeurosis  intervenes  between 

APONEUBOSIS.  the  muscles  and  the  mucous  membrane  of  the 

pharynx.  It  is  attached  to  the  basilar  process  of  the  occipital 
bone,  and  to  the  points  of  the  petrous  portions  of  the  temporal 
bones.  It  maintains  the  strength  and  integrity  of  the  pharynx  at 
its  upper  part,  where  the  muscular  fibres  are  deficient ;  but  it 
gradually  diminishes  in  thickness  as  it  descends,  and  is  finally  lost 
on  the  oesophagus.  Notice  the  number  of  mucous  glands  upon 
this  aponeurosis,  especially  near  the  base  of  the  skull  and  the 
Eustachian  tube.  These  glands  sometimes  enlarge  and  occasion 
deafness  from  the  pressure  on  the  tube. 

OPENINGS  INTO  Lay  open  the  pharynx  by  a  longitudinal  incision 

THE  PHARYNX.  in  the  middle  line,  up  to  the  pharyngeal  tubercle ; 

then  divide  transversely,  for  a  short  distance,  that  part  of  the 
pharyngeal  aponeurosis  which  is  attached  to  the  basilar  process, 
so  as  the  better  to  view  the  cavity  of  the  pharynx.  Observe  the 
seven  openings  leading  into  it  (fig.  54)  : — 1.  The  two  posterior 
nares:  below  the  nares  is  the  soft  palate,  with  the  uvula.  2.  On 
either  side  of  them,  near  the  lower  turbinated  bones,  are  the 
openings  of  the  Eustachian  tubes.  3.  Below  the  soft  palate  is  the 
communication  with  the  mouth,  called  the  isthmus  faucium.  On 
either  side  of  this  are  two  folds  of  mucous  membrane,  constituting 
the  anterior  and  posterior  half-arches  of  the  palate ;  between  them 
are  the  tonsils.  Below  the  isthmus  faucium  is  the  epiglottis,  which 
is  connected  to  the  base  of  the  tongue  by  three  folds  of  mucous 
membrane.  4.  Below  the  epiglottis  is  the  aperture  of  the  larynx. 
5.  Lastly,  is  the  opening  into  the  oesophagus.1 

1  On  reflecting  the  mucous  membrane  at  the  pharyngeal  termination  of  the 
Eustachian  tube,  a  thin  pale  muscle,  the  salpingo-pharyngeus,  can  be  made  out. 
It  arises  by  a  thin  tendon  from  the  Eustachian  tube,  and  joins  the  palato-pharyn- 
geus.  It  is  lost  among  the  fibres  of  the  constrictor  muscles. 


MUCOUS  MEMBRANE  OF  THE  PHARYNX. 


231 


The  pharynx  consists  of  three  coats,  viz.,  muscular,  fibrous  and 
Ynucous.     The  two  former  have  been  already  described. 

Mucous  The  mucous  membrane  is   common  to  the  en- 

MEMBRANE.  tire  tract  of  the  respiratory  passages  and  the  ali- 


Eustachian  tube. 
Levator  palati  m. 


L —  Tensor  palati  m. 
Hamular  process. 


Posterior  palatine  arch. 
Tonsil. 

Anterior  palatine  arch. 

Epiglottis. 

Aryteno-epiglottidean 
fold. 

Opening  into  the 
larynx. 


Opening  into  the 
oesophagus. 


DIAGRAMMATIC   VIEW    OF   THE    PHARYNX   LAID    OPEN    FROM   BEHIND. 

mentary  canal.  This  membrane,  however,  presents  varieties  in  the 
different  parts  of  these  channels,  according  as  they  are  intended  as 
passages  for  air  or  for  food.  The  mucous  membrane  of  the  pharynx 


232  THE    SOFT    PALATE. 

above  the  velum  palati,  being  intended  to  transmit  air  only,  is  very 
delicate  in  its  texture,  and  lined  by  columnar  ciliated  epithelium 
like  the  rest  of  the  air-passages.  But  opposite  the  fauces,  the 
mucous  membrane  resembles  that  of  the  mouth,  and  is  provided 
with  squamous  epithelium.  At  the  back  of  the  larynx  the  mem- 
brane is  corrugated  into  folds,  to  allow  the  expansion  of  the 
pharynx  during  the  passage  of  the  food. 

The  membrane  is  lubricated  by  a  secretion  from  the  nume- 
rous mucous  glands  which  are  situated  in  the  submucous  tissue 
throughout  the  whole  extent  of  the  pharynx,  particularly  in  the 
neighbourhood  of  the  Eustachian  tubes.1 

POSTERIOR  These  are  two  oval  openings,  each  of  which  is 

OPENINGS  OF  THE  about  an  inch  in  the  long,  and  half  an  inch  in  the 
NASAL  Foss^.  short  diameter.  They  are  bounded  above  by  the 

body  of  the  sphenoid  bone,  externally  by  its  pterygoid  plate,  below 
by  the  horizontal  portion  of  the  palate  bone  ;  they  are  separated 
from  each  other  by  the  vomer. 

On  removing  the  mucous  membrane  from  the  posterior  part  of 
the  roof  of  the  nose  and  the  top  of  the  pharynx,  you  will  find 
beneath  it  much  fibrous  tissue.  Hence  polypi  growing  from  these 
parts  are,  generally,  of  a  fibrous  nature. 

ISTHMUS  This  name  is  given  to  the  opening  by  which 

FAUCIUM.  the  mouth  communicates  with  the  pharynx.     It 

is  bounded,  above  by  the  soft  palate  and  uvula,  below  by  the 
root  of  the  tongue,  and  on  either  side  by  the  arches  of  the  palate, 
enclosing  the  tonsils  between  them. 

SOFT  PALATE,  OB  This  moveable  prolongation  of  the  roof  of  the 
VELUM  PENDULUM  mouth  is  attached  to  the  border  of  the  hard 
PALATI.  palate,  and  laterally  to  the  side  of  the  pharynx. 

Posteriorly  it  has  a  free  edge,  with  a  pendulous  conical  projection 
in  the  centre,  called  the  uvula.  It  constitutes  an  imperfect  parti- 
tion between  the  mouth  and  the  posterior  nares.  Its  upper  or 
nasal  surface  is  convex  and  continuous  with  the  floor  of  the  nose  ; 
its  lower  surface  is  concave,  in  adaptation  to  the  back  of  the 
tongue,  and  is  marked  in  the  middle  by  a  ridge  or  raphe,  indicat- 
ing its  original  formation  by  two  lateral  halves.  The  soft  palate, 
1  This  aggregation  of  mucous  glands  is  called  the  pharyngeal  tonsil. 


ARCHES  OF  THE  SOFT  PALATE.  233 

when  at  rest,  hangs  obliquely  downwards  and  backwards ;  but  in 
swallowing,  it  is  raised  to  the  horizontal  position  by  the  levatores 
palati,  comes  into  apposition  with  the  back  of  the  pharynx,  and 
thus  prevents  the  food  from  passing  through  the  nose. 

On  making  a  perpendicular  section  through  the  soft  palate, 
you  come  first  upon  the  oral  mucous  membrane  ;  then  you  see  that 
the  great  bulk  of  it  is  made  up  of  muciparous  glands,  which  lie 
thick  on  its  under  surface  to  lubricate  the  passage  of  the  food. 
Above  these  glands  is  the  thin  layer  of  the  palato-glossus,  then 
the  insertion  of  the  tensor  palati  forming  the  broad  aponeurosis  of 
the  palate ;  still  higher,  are  the  two  portions  of  the  palato-pharyn- 
geus,  separated  by  the  fibres  of  the  levator  palati,  the  azygos  uvulse, 
and,  lastly,  the  nasal  mucous  membrane.  The  soft  palate  is  sup- 
plied with  blood  by  the  descending  palatine  branch  of  the  internal 
maxillary,  the  ascending  palatine  branch  of  the  facial,  the  ascend- 
ing pharyngeal  and  the  dorsales  linguae  of  the  lingual  artery.  Its 
nerves  are  derived  from  the  palatine  branches  of  the  superior 
maxillary  division  of  the  fifth  and  from  the  glosso-pharyngeal. 

The  uvula  projects  from  the  middle  of  the  soft 
palate,  and  gives  the  free  edge  of  it  the  appearance 
of  a  double  arch.  It  contains  a  number  of  muciparous  glands,  and 
a  small  muscle,  the  azygos  uvulce.  Its  length  varies  according  to 
the  state  of  its  muscle.  It  occasionally  becomes  permanently  elon- 
gated, and  causes  considerable  irritation,  a  tickle  in  the  throat,  and 
harassing  cough.  When  you  have  to  remove  a  portion  of  it,  cut 
off  only  the  redundant  mucous  membrane. 

ARCHES  OR  ^ne  soft  Pa^e  is  connected  with  the  tongue 

PILLARS  OF  THE  and  pharynx  by  two  folds  of  mucous  membrane 
PALATE.  on  each  side,  enclosing  muscular  fibres.  These  are 

the  anterior  and  posterior  arches  or  pillars  of  the  palate.  The  ante- 
rior arch  describes  a  curve  downwards  and  forwards,  from  the  base 
of  the  uvula  to  the  side  of  the  tongue.  It  is  well  seen  when  the 
tongue  is  extruded.  The  posterior  arch,  commencing  at  the  side  of 
the  uvula,  curves  downwards  and  backwards,  along  the  free  margin 
of  the  palate,  and  terminates  on  the  side  of  the  pharynx.  The 
posterior  arches,  when  the  tongue  is  depressed,  can  be  seen  through 
the  span  of  the  anterior.  The  pillars  of  each  side  diverge  from 


234  MUSCLES  OF  THE  SOFT  PALATE. 

their  origin,  and  in  the  triangular  space  thus  formed  is  situated 
the  tonsil.  The  chief  use  of  the  arches  of  the  palate  is  to  assist  in 
deglutition.  The  anterior,  enclosing  the  palato-glossi  muscles,  con- 
tract so  as  to  prevent  the  food  from  coming  back  into  the  mouth  ; 
the  posterior,  enclosing  the  palato-pliaryngei,  contract  like  side 
curtains,  and  co-operate  in  preventing  the  food  from  passing  into 
the  nose.  In  vomiting,  food  does  sometimes  escape  through  the 
nostrils,  but  one  cannot  wonder  at  this,  considering  the  violence 
with  which  it  is  driven  into  the  pharynx. 

MUSCLES  OF  THE         The  muscles  of  the  soft  palate  lie  immediately 
SOFT  PALATE.  beneath  the  mucous  membrane.     There  are  five 

pairs — namely,  the  levatores  palati,  the  circumflexi  or  tensores 
palati,  the  palato-glossi,  the  palato-pharyngei,  and  the  azygos 
uvulee.  This  last  pair  is  sometimes  described  as  a  single  muscle. 
To  clean  the  muscles,  the  soft  palate  should  be  made  tense  by 
means  of  hooks,  as  they  are  severally  dissected. 

This  muscle  arises  from  the  under  aspect  of  the 
LEVATOB  PALATI.  ,,    ,  .          „    .  . 

apex  oi  the  petrous  portion  of  the  temporal  bone, 

and  from  the  under  part  of  the  cartilage  of  the  Eustachian  tube. 
It  descends  obliquely  inwards,  and  then  passes  over  the  concave 
border  of  the  superior  constrictor  into  the  pharynx,  where  its 
fibres  spread  out  and  are  inserted  along  the  upper  surface  of  the 
soft  palate  below  the  azygos  uvulse,  meeting  those  of  its  fellow  in 
the  middle  line  (fig.  54).  Its  action  is  to  raise  the  soft  palate,  so 
as  to  make  it  horizontal  in  deglutition.  It  is  supplied  by  the 
descending  palatine  branch  from  the  spheno-palatine  ganglion. 

CIECUMFLEXUS  This  muscle  is  situated  between  the  internal 

OR  TENSOR  PALATI.  pterygoid  m.  and  the  internal  pterygoid  plate  of 
the  sphenoid  bone.  It  arises  by  a  flattened  muscular  belly  from 
the  scaphoid  fossa,  and  from  the  spine  of  the  sphenoid ;  from  the 
vaginal  process  of  the  temporal  bone  and  from  the  outer  and 
anterior  side  of  the  cartilage  of  the  Eustachian  tube.  Thence  it 
descends  perpendicularly,  and  ends  in  a  tendon  which  winds  round 
the  hamular  process,  where  there  is  a  synovial  bursa.  Now  chang- 
ing its  direction,  the  tendon  passes  horizontally  inwards,  and 
expands  into  a  broad  aponeurosis,  which  is  inserted  into  the 
horizontal  plate  of  the  palate  bone,  and  is  also  connected  to  its 


THE    TONSILS.  235 

fellow  of  the  opposite  side.  It  gives  strength  to  the  soft  palate. 
A  synovial  membrane  facilitates  the  play  of  the  tendon  round  the 
hanralar  process.  Its  action  is  to  draw  down  and  tighten  the  soft 
palate,  and,  owing  to  its  insertion  into  the  palate  bone,  also  to 
keep  the  Eustachian  tube  open.  Its  nerve  is  derived  from  the 
otic  ganglion,  and  enters  the  muscle  on  its  inner  aspect. 

AZYGOS  OB  This  consists  of  two  thin  bundles  of  parallel 

LEVATOB  UVUM:.  muscular  fibres  situated  one  on  each  side  of  the 
middle  line.  It  arises  from  the  aponeurosis  of  the  palate  and  de- 
scends along  the  uvula  nearly  down  to  its  extremity.  It  receives 
its  nerve  from  the  descending  palatine  branch  of  the  spheno- 
palatine  ganglion. 

PALATO-GLOSSUS          These  muscles  are  contained  within  the  arches 
AND  PALATO-  of  the  soft  palate,  and  the  mucous  membrane  must 

PHABYNGEUS.  |-,e  removed  in  order  to  expose  them.     The  -palaio- 

glossus,  within  the  anterior  arch,  proceeds  from  the  anterior  surface 
of  the  soft  palate  to  the  side  of  the  tongue,  and  is  lost  in  the  stylo- 
glossus  muscle.  The  palato-pliarynfjeus,  within  the  posterior  arch, 
arises  from  the  posterior  border  of  the  soft  palate  by  two  origins, 
separated  by  the  levator  palati.  As  it  descends  its  fibres  spread 
out  and,  passing  along  the  side  of  the  pharynx,  blend  with  the 
fibres  of  the  inferior  constrictor  and  the  stylo-pharyngeus.  Both 
these  muscles  are  supplied  by  the  descending  palatine  branches  of 
the  spheno-palatine  ganglion. 

The  tonsils  are  two  glandular  bodies,  situated 
at  the  entrance  of  the  fauces,  between  the  arches 
of  the  soft  palate.  They  are  rounded  in  shape,  and  their  use  is  to 
lubricate  the  fauces  during  the  passage  of  the  food.  On  their 
inner  surface  are  visible  from  twelve  to  fifteen  orifices  leading  into 
crypts,  which  make  the  tonsil  appear  like  the  shell  of  an  almond. 
Hence,  as  well  as  from  their  oval  figure,  they  are  called  the 
amyydalce. 

These  openings  lead  into  small  follicles  in  the  substance  of  the 
tonsil,  lined  by  mucous  membrane.  Their  walls  are  thick,  and 
around  them  is  a  layer  of  closed  cells  (like  Peyer's  glands)  situated 
in  the  submucous  tissue.  The  fluid  secreted  by  these  cells  is  viscid 
and  transparent,  in  the  healthy  state  :  but  it  is  apt  to  become 


236  EUSTACHIAN    TUBE. 

white  and  opaque  in  inflammatory  affections  of  the  tonsils,  and 
occasionally  accumulates  in  these  superficial  depressions,  giving 
rise  to  the  deceptive  appearance  of  a  small  ulcer,  or  a  slough,  or 
even  a  false  membrane  on  the  part. 

The  tonsil  lies  close  to  the  inner  side  of  the  internal  carotid 
artery.  It  is  only  separated  from  this  vessel  by  the  ascending 
pharyngeal  artery,  the  superior  constrictor,  and  the  aponeurosis  of 
the  pharynx.  Therefore,  in  removing  a  portion  of  the  tonsil,  or  in 
opening  an  abscess  near  it,  the  point  of  the  instrument  should 
never  be  directed  outwards,  but  inwards  towards  the  mesial  line.1 
The  tonsil  is  supplied  with  blood  by  the  tonsillar  and  palatine 
branches  of  the  facial,  and  by  the  descending  palatine  branch  of 
the  internal  maxillary.  Nerves  are  furnished  to  it  from  the  glosso- 
pharyngeal  and  from  Meckel's  ganglion. 

EUSTACHIAN  This  canal  conveys  air  from  the  pharynx  to  the 

TUBE,  tympanum.     Its  orifice  is  situated  opposite  the 

back  part  of  the  inferior  spongy  bone.  The  direction  of  the  tube 
from  the  pharynx  is  upwards,  backwards,  and  outwards ;  it  is  an 
inch  and  a  half  long.  The  narrowest  part  is  about  the  middle, 
and  here  its  walls  are  in  contact.  Near  the  tympanum  its  walls 
are  osseous,  but  towards  the  pharynx  they  are  composed  of  fibro- 
cartilage  and  fibrous  membrane.  The  cartilaginous  end,  about  an 
inch  in  length,  projects  between  the  origins  of  the  levator  and  the 
tensor  palati,  and  gives  attachment  to  some  of  their  fibres.  It  is 
situated  at  the  base  of  the  skull,  in  the  furrow  between  the  petrous 
portion  of  the  temporal  and  the  great  wing  of  the  sphenoid  bone. 
It  adheres  closely  to  the  bony  furrow,  as  well  as  to  the  fibro- 
cartilage  filling  up  the  foramen  lacerum  medium.  The  orifice  is 
not  trumpet-shaped,  as  usually  described,  but  an  elliptical  slit 
about  half  an  inch  long^  and  nearly  perpendicular.  The  fibro- 
cartilage  bounds  it  only  on  the  inner  and  the  upper  part  of  the 

1  Cases  are  related  by  Portal  and  Beclard,  in  which  the  carotid  artery  was 
punctured  in  opening  an  abscess  in  the  tonsil.  The  result  was  immediately  fatal 
haemorrhage.  It  should,  however,  be  borne  in  mind  that  the  artery  usually  injured 
is  the  tonsillar  branch  of  the  facial  artery,  and  not  the  internal  carotid.  •  The 
surgical  treatment  of  this  accident  is  therefore  ligature  of  the  external  carotid 
artery  between  its  superior  thyroid  and  lingual  branches,  and  not  ligature  of  the 
common  carotid  artery  as  is  often  recommended. 


MECHANISM    OF   DEGLUTITION.  237 

circumference  ;  the  integrity  of  the  canal  below  is  maintained  by 
tough  fibrous  membrane. 

The  Eustachian  tube  is  lined  by  a  continuation  of  the  mucous 
membrane  of  the  pharynx,  and  covered  by  ciliated  epithelium. 
That  which  lines  the  cartilaginous  portion  of  the  tube  is  thick  and 
vascular,  and  gradually  becomes  thinner  towards  the  tympanum. 
Hence,  inflammatory  affections  of  the  throat  or  tonsils  are  liable  to 
l)e  attended  with  deafness,  from  temporary  obstruction  of  the  tube. 
Mucous  glands  surround  the  orifice  of  the  tube,  and  are  similar 
in  nature  and  function  to  the  glands  beneath  the  mucous  membrane 
of  the  mouth,  the  palate,  and  the  pharynx. 

The  hard  palate,  formed  by  the  superior  maxil- 
lary and  palate  bones,  is  a  resisting  surface  for  the 
tongue  in  tasting,  in  mastication,  in  deglutition,  and  in  the  articu- 
lation of  sounds.  The  tissue  covering  the  bones  is  thick  and  close 
in  texture,  and  firmly  united  to  the  asperities  on  the  bones.  But 
it  is  not  everywhere  of  equal  thickness.  Along  the  raphe  in  the 
mesial  line,  it  is  much  thinner  than  at  the  sides ;  for  this  reason, 
the  hard  palate  is  in  this  situation  more  prone  to  be  perforated  in 
syphilitic  disease. 

A  thick  layer  of  glands  (glandulce  palatince)  is  arranged  in 
rows  on  either  side  of  the  hard  palate.  These  glands  become  more 
numerous  and  larger  towards  the  soft  palate.  Their  orifices  are 
visible  to  the  naked  eye.  The  mucous  membrane  has  a  very  thick 
epithelial  coat,  which  gives  the  white  colour  to  the  palate.  The 
descending  palatine  branch  of  the  internal  maxillary  artery,  and 
the  palatine  nerves  from  the  superior  maxillary,  may  be  traced 
along  each  side  of  the  roof  of  the  mouth.  The  ramifications  of 
these  arteries  and  nerves  supply  the  soft  as  well  as  the  hard  palate. 
MECHANISM  OF  With  the  anatomy  of  the  parts  fresh  in  your 

DEGLUTITION.  mind,  consider  for  a  moment  the  mechanism,  of 

deglutition.  The  food,  duly  masticated,  is  collected  into  a  mass 
upon  the  back  of  the  tongue ;  the  lower  jaw  is  then  closed  to  give 
a  fixed  point  for  the  action  of  the  muscles  which  raise  the  os 
hyoides  and  larynx,  and  the  food  is  carried  back  into  the  pharynx 
by  the  pressure  of  the  tongue  against  the  palate,  at  the  same 
time  that  the  pharynx  is  elevated  and  expanded  to  receive  it  (by 


238  DISSECTION    OF   THE    LARYNX. 

the  stylo-pharyngei  on  each  side).1  The  food,  having  reached  the 
pharynx,  is  prevented  from  ascending  into  the  nasal  passages  by 
the  approximation  of  the  posterior  palatine  arches,  and  the  eleva- 
tion of  the  soft  palate,  which  thus  forms  a  horizontal  temporary 
roof  to  the  pharynx;  it  is  prevented  from  returning  into  the 
mouth  by  the  pressure  of  the  retracted  tongue,  and  the  contraction 
of  the  anterior  palatine  arches  :  it  cannot  enter  the  larynx,  because 
its  upper  opening  is  closed  and  protected  by  the  falling  of  the 
epiglottis :  -  consequently,  being  forcibly  compressed  by  the  con- 
strictors of  the  pharynx,  the  food  passes  into  the  oesophagus, 
through  which  it  is  conveyed  into  the  stomach  by  the  undulatory 
contraction  of  that  tube. 

The  food  passes  with  different  degrees  of  rapidity  through  the 
different  parts  of  its  course  ;  but  most  rapidly  through  the  pharynx. 
The  necessity  of  this  is  obvious,  as  the  air-tube  must  be  closed 
while  the  food  passes  over  it,  and  the  closure  produces  a  temporary 
interruption  to  respiration.  The  progress  of  the  food  through  the 
oesophagus  is  slow  and  gradual. 


DISSECTION   OP  THE  LAEYNX. 

SITUATION  AND  The   larynx   is  the  upper  dilated  part  of  the 

EELATIONS.  windpipe,  in  which    phonation   takes   place.     It 

consists  of  numerous  cartilages  articulated  together  to  form  an 
open  tube,  and  to  protect  the  delicate  structures  concerned  in 
vocalisation. 

It  forms  a  prominence  in  the  middle  line  of  the  neck,  covered 
in  front  by  the  integument  and  cervical  fasciae,  the  sterno-hyoid, 
sterno-thyroid,  and  thyro-hyoid  muscles,  and  the  thyroid  body. 
It  has  the  large  vessels  of  the  neck  on  each  side.  Above,  it 
is  attached  to  the  hyoid  bone ;  below,  it  is  continuous  with  the 

1  The  larynx  being  also  elevated  and  drawn  forward,  a  greater  space  is  thus  left 
between  it  and  the  vertebrae  for  the  distention  of  the  pharynx. 

2  This  falling  of  the  epiglottis  is  effected,  not  by  special  muscular  agency,  but 
by  the  simultaneous  elevation  of  the  larynx  and  the  retraction  of  the  tongue.     A 
perpendicular  section  through  all  the  parts  concerned  is  necessary  to  show  the 
working  of  this  mechanism. 


LIGAMENTS    OF    THE    OS    HYOIDES. 

trachea  ;  behind  it,  is  the  pharynx,  into  the  anterior  part  of  which 
it  opens. 

Before  commencing  the  dissection  of  the  larynx,  the  student 
should  make  himself  acquainted  with  the  cartilages  which  compose- 
it,  and  the  ligaments  which  connect  them,  as  seen  in  a  dry  pre- 
paration. 

This  bone,  named  from  its  resemblance  to  the 
Greek  Upsilon,  is  situated  between  the  larynx  and 
the  tongue,  and  serves  for  the  attachment  of  the  muscles  of  the 
tongue.  It  may  be  felt  immediately  below,  and  one  inch  and  a 
half  behind,  the  symphysis  of  the  jaw.  It  is  arched  in  shape,  and 
consists  of  a  body,  two  greater  and  two  lesser  cornua.  The  body 
(basi-hyafy  is  the  thick  central  portion.  Its  anterior  surface  is 
convex,  and  has  a  median  vertical  ridge :  on  each  side  of  which 
are  depressions  for  the  attachments  of  muscles;  its  posterior 
surface  is  smooth,  deeply  concave,  and  corresponds  to  the  epi- 
glottis. The  greater  cornua  (thyro-hyals),  right  and  left,  project 
backwards  for  about  an  inch  and  a  half,  with  a  slight  inclination 
upwards,  and  terminate  in  blunt  ends  tipped  with  cartilage.  In 
young  subjects  they  are  connected  to  the  body  of  the  bone  by 
fibro-cartilage ;  this  in  process  of  years  becomes  ossified.  The 
lesser  cornua  (cerato-liyals)  are  connected,  one  on  each  side,  to  the 
point  of  junction  between  the  body  and  the  greater  cornua,  by 
means  of  a  little  joint  lined  with  synovial  membrane,  which  admits 
of  free  motion.  They  are  of  the  size  of  a  barleycorn,  and  give 
attachment  to  the  stylo-hyoid  ligaments. 

The  os  hyoides  is  connected  with  the  thyroid 
cartilage  by  several  ligaments,  which  contain  a 
quantity  of  elastic  tissue.  There  is: — 1.  The  thyro-hyoid  mem- 
brane, a  broad  fibrous  membrane,  which  proceeds  from  the  supe- 
rior border  of  the  thyroid  cartilage  to  the  upper  and  posterior 
part  of  the  hyoid  bone.  In  front  of  this  membrane  there  is  a 
bursa,  of  which  the  use  is  to  facilitate  the  play  of  the  thyroid 
cartilage  behind  the  os  hyoides.  The  central  portion  is  stronger 
than  the  lateral,  and  is  called  the  anterior  thyro-hyoid  ligament. 
Through  the  lateral  part  of  this  membrane,  the  superior  laryngeal 
nerve  and  artery  enter  the  larynx.  2.  The  right  and  left  lateral 


240  THYROID    CARTILAGE. 

thyro-hyoid  ligaments  extend  between  the  extremities  of  the  greater 
cornua  of  the  os  hyoides,  and  the  ascending  cornua  of  the  thyroid 
cartilage.  They  contain  a  small  nodule  of  cartilage  (cartilayo 
triticea). 

CARTILAGES  OF  The  framework  of  the  larynx  is  composed  of 

THE  LABYNX.  nine  cartilages — viz.,  the  thyroid,  the  cricoid,  the 

two  arytenoid,  the  two  cornicula  laryngis,  the  two  cuneiform 
cartilages,  and  the  epiglottis.  These  are  connected  by  joints  and 
elastic  ligaments,  so  that  they  can  be  moved  upon  each  other  by 
their  respective  muscles ;  the  object  of  this  motion  being  to  act 
upon  two  elastic  ligaments,  called  the  vocal  cords,  upon  the  vibra- 
tion of  which  phonation  depends. 

THYROID  CAB-  This  cartilage,  so  called  because  it  shields  the 

TILAGE.  mechanism  behind  it,1  consists  of  two  lateral 

halves  (cdce),  united  at  an  acute  angle  in  front,  which  forms  the 
prominence  termed  the  pomum  Adami.  This  prominence  presents 
a  notch  at  its  upper  part,  to  allow  it  to  play  behind  the  os  hyoides 
in  deglutition.  There  is  a  bursa  in  front  of  it.  Each  ala  is  some- 
what quadrilateral  in  form,  and  presents  for  examination  two 
surfaces  and  four  borders.  The  outer  stirface  of  each  ala  is  marked 
by  an  oblique  line  passing  downwards  and  forwards  from  the  base 
of  the  upper  cornu,  which  gives  attachment  to  the  sterno-thyroid 
and  thyro-hyoid  muscles.  The  smooth  surface  behind  the  ridge 
gives  attachment  to  the  inferior  constrictor.  The  inner  surface  is 
smooth,  slightly  concave,  and  is  covered  with  mucous  membrane. 
In  the  acute  angle  in  front  there  are  attached  from  above  down- 
wards, the  epiglottis,  the  false  and  true  vocal  cords,  the  thyro- 
arytenoidei  and  thyro-epiglottidei  muscles.  The  inferior  border 
is  slightly  arched  in  the  middle,  affording  attachment  to  the  crico- 
thyroid  membrane,  and  on  either  side  presents  a  convex  promi- 
nence, which  gives  attachment  to  the  crico-thyroid  muscle  and  the 
crico-thyroid  membrane.  The  superior  border  is  nearly  horizontal, 
and  affords  attachment  to  the  thyro-hyoid  membrane.  The  posterior 
border  is  thick,  rounded  and  nearly  vertical,  and  gives  insertion  to 
the  stylo-pharyngeus  and  palato-pharyngeus  muscles.  This  border 
terminates,  above  and  below,  in  round  projections  called  the  upper 

1  ®vpf6s,  a  shield. 


CEICOID   CARTILAGE.  241 

and  lower  cornua.  •  The  upper  is  the  longer ;  the  lower  articulates 
with  the  side  of  the  cricoid  cartilage. 

CEICOID  CAB-  This  cartilage,  named  from  its  resemblance  to 

TILAGE.  a  ring,1  is  situated  below  the  thyroid.     It  is  not 

of  equal  depth  all  round.  It  is  narrow  in  front,  where  it  may 
be  felt  about  a  quarter  of  an  inch  below  the  thyroid ;  from  this 
part,  the  upper  border  gradually  rises,  so  that,  posteriorly,  the 
ring  is  an  inch  in  vertical  depth,  and  occupies  part  of  the  interval 
left  between  the  alee  of  the  thyroid.  In  the  middle  of  this  broad 
posterior  surface  is  a  vertical  ridge,  on  either  side  of  which  observe 
a  superficial  excavation  for  the  origin  of  the  crico-arytenoidei 
postici :  to  the  lower  part  of  the  vertical  ridge  are  attached  some 
of  the  longitudinal  fibres  of  the  oesophagus.  On  its  upper  part  are 
two  oval  slightly  convex  surfaces  for  the  articulation  of  the  ary- 
tenoid  cartilages,  between  which  is  a  concavity  for  the  attachment 
of  the  arytenoideus.  In  front,  its  upper  border  presents  a  broad 
excavation  to  which  the  crico-thyroid  membrane  (on  which  is  seen 
the  crico-thyroid  artery),  is  attached.  On  its  outer  surface,  external 
to  the  depression  for  the  crico-arytenoideus  posticus,  is  an  elevated 
facet  which  articulates  with  the  inferior  cornu  of  the  thyroid 
cartilage.  In  front  of  this  articular  surface  it  gives  attachment 
to  the  inferior  constrictor  of  the  pharynx.  The  lower  border  is 
straight,  and  is  connected  by  fibrous  membrane  to  the  first  ring  of 
the  trachea.  The  inner  surface  is  smooth,  and  the  upper  border  is 
elliptical ;  its  lower  being  nearly  circular. 

The  thyroid  cartilage  is  connected  to  the  cricoid 

LIGAMENTS.  ,  *,  ,    '      .        ,        .,       T  . 

by  a  membrane — the  cnco-tfiyroid.     It  consists  of 

a  median  triangular  portion,  composed  mainly  of  elastic  tissue,  with 
its  base  directed  downwards.  The  lateral  portions  are  thin  and 
membranous,  extending  as  far  backwards  as  the  articular  facets 
for  the  thyroid  cartilage,  and  are  intimately  connected  with  the 
inferior  vocal  cords.  Between  the  inferior  cornu  of  the  thyroid 
cartilage  and  the  cricoid  there  is  a  distinct  joint,  having  a  sy  no  vial 
membrane,  and  strengthened  by  a  capsular  ligament.  The  arti- 
culation allows  of  a  movement  revolving  upon  its  own  axis,  and, 
consequently,  permits  the  approximation  of  the  two  cartilages. 

1  K/ji'/cos,  a  ring. 


242  ARYTENOID   CARTILAGES. 

ABYTENOID  These  cartilages  are  situated,  one  on  each  side, 

CARTILAGES.  at  the  back  of  the  upper  border  of  the  cricoid 

cartilage.  In  the  recent  state,  before  the  membranes  and  muscles 
have  been  removed,  the  space  between  them  resembles  the  lip  of  a 
pitcher  l ;  hence  their  name.  Each  is  pyramidal,  with  the  apex 
upwards,  is  about  five  or  six  lines  in  height,  and  three  lines  in 
diameter  at  its  base,  and  presents  for  examination  three  surfaces 
(marked  off  by  three  borders),  a  base  and  an  apex.  The  posterior 
surface  of  each  is  triangular  and  concave,  and  gives  attachment 
to  the  arytenoideus  muscle ;  the  anterior  surface  is  irregular  and 
convex,  affording  attachment  to  the  thyro-arytenoideus,  and  to  the 
superior  or  false  vocal  cord;  the  internal  surface,  the  narrowest 
and  nearly  flat,  faces  the  corresponding  surface  of  the  opposite 
cartilage,  and  is  covered  with  mucous  membrane.  The  base  is 
broad,  and  presents  a  smooth  somewhat  concave  triangular  surface 
which  articulates  with  the  cricoid  cartilage ;  in  front  of  the  base 
is  the  pointed  anterior  angle,  which  gives  attachment  to  the  true 
vocal  cord,  and  contributes  to  form  part  of  the  boundary  of  the 
rima  glottidis ;  at  the  outer  and  back  part  of  the  base  is  the 
external  angle,  into  which  certain  muscles  moving  the  cartilage 
are  inserted,  viz.  the  crico-arytenoideus  posticus  and  crico-aryte- 
noideus  lateralis.  The  base  is  articulated  with  the  cricoid  by  a  joint 
which  has  a  loose  capsular  ligament  and  a  synovial  membrane,  per- 
mitting motion  in  all  directions,  like  the  first  joint  of  the  thumb. 
The  apex  is  truncated  and  points  backwards  and  inwards.  It  is  sur- 
mounted by  a  cartilaginous  nodule,  called  the  corniculum  laryngis. 

CORNICULA.  Are  two  small  conical  cartilaginous  nodules,  and 

LARYNGIS.  continue  the  direction  of  the  arytenoid  cartilages 

upwards  and  inwards. 

CUNEIFORM  These  cartilages,  sometimes  called  the  cartilages 

€ABTILAGES.  of  Wrisberg,  are  conical  in  form,  and  somewhat 

curved,  with  their  broader  part  directed  upwards  and  forwards. 
They  are  contained  in  the  aryteno-epiglottidean  fold. 

This  piece  of  yellow  fibro-cartilage  is  situated  in 

the  middle  line,  and  projects  over  the  larynx  like 

a  valve.     It  is  like  a  leaf  with  its  stalk  directed  downwards.     Its 

,  a  pitcher. 


EPIGLOTTIS.  243 

•ordinary  position  is  perpendicular,  leaving  the  upper  opening  of 
the  larynx  free  for  respiration;  but  during  the  elevation  of  the 
larynx  in  deglutition  it  becomes  horizontal,  falls  downwards  and 
backwards  over  the  larynx,  and  prevents  the  entrance  of  food  into 
it.  This  descent  of  the  epiglottis  is  accomplished,  not  by  special 
muscular  agency,  but  by  the  simultaneous  elevation  of  the  larynx 
and  the  retraction  of  the  tongue.  Its  apex  or  lower  part  is  at- 
tached by  the  tliyro-epiglottic  ligament  to  the  angle  of  the  thyroid 
cartilage;  it  is  also  connected  by  an  elastic  ligament,  hyo-epigloHic, 
to  the  posterior  surface  of  the  os  hyoides.  Laterally,  its  borders 
are  rather  turned  backwards,  and  to  them  are  attached  two  folds 
•of  mucous  membrane,  which  pass  to  the  arytenoid  cartilages, 
called  the  aryteno-epiglottic  folds.  Its  anterior  surface  is  only  free 
at  its  base,  where  it  is  connected  with  the  base  of  the  tongue 
by  the  three  glosso-epiglottic  folds.  Its  posterior  or  laryncjeal 
•surface  is  smooth,  concavo-convex  and  free,  and  looks  towards 
the  larynx.  The  surface  of  the  epiglottis  is  closely  invested  by 
mucous  membrane  ;  this  being  removed,  the  yellow  cartilage  of  the 
epiglottis  is  seen  pitted  and  often  perforated  by  the  small  mucous 
glands. 

The  cartilages  of  the  larynx  resemble  those  of  the  ribs  in  struc- 
ture. In  the  young  they  are  dense  and  elastic,  but  some  have  a 
tendency  to  ossify  with  age.  In  very  old  subjects,  the  thyroid  and 
cricoid  cartilages  are  often  completely  ossified,  and  their  interior 
presents  an  areolar  tissue,  containing  oily  matter,  analogous  to  the 
spongy  texture  of  the  bones.  The  epiglottis,  cornicula  laryngis, 
and  cuneiform  cartilages  are  rarely  ossified,  on  account  of  their 
consisting  of  yellow  fibro-cartilage  resembling  that  of  the  ear  and 
nose. 

The  larynx  must  now  be  examined  in  its  perfect  condition. 
Mucous  MEM-  The  mucous  membrane  lines  the  whole  of  the  in- 

BRANE  OF  THE  terior  of  the  larynx,  being  continuous  above  with 

LABYNX.  tlaai,  of  the  pharynx  and  mouth,  below  with  that  of 

the  trachea.  It  is  intimately  adherent  to  the  posterior  part  of  the 
epiglottis  and  to  the  true  vocal  cords ;  elsewhere  it  is  loosely  con- 
nected to  the  subjacent  structures  by  an  abundance  of  areolar 
tissue,  which  admits  of  its  being  elevated  into  large  folds.  This  is 

R  2 


244  MUCOUS  MEMBRANE  OF  THE  LARYNX. 

chiefly  found  about  the  upper  opening  of  the  larynx,  and  it  deserve* 
notice  from  the  rapidity  with  which  it  becomes  the  seat  of  serous 
effusion  in  acute  inflammation  of  the  larynx,  and  thus  produces 
symptoms  of  suffocation.  In  the  remaining  part  of  the  interior  of 
the  larynx  the  mucous  membrane  is  moderately  adherent  to  the 
subjacent  tissues,  and  at  the  upper  or  false  vocal  cord  it  redupli- 
cates upon  itself  and  then  lines  the  sacculus  laryngis.  Naturally, 
the  mucous  membrane  is  of  pale  rose  colour,  except  where  it  covers 
the  cushion  of  the  epiglottis,  where  it  is  bright  pink.  It  is  covered 
by  columnar  ciliated  epithelium  below  the  false  vocal  cords,  and 
this  variety  is  continued  up  the  epiglottis  as  high  as  its  middle ; 
above  this,  by  squamous  epithelium.  From  the  root  of  the  tongue 
to  the  anterior  surface  of  the  epiglottis,  the  membrane  forms  three 
folds,  cjlosso-epiglottic,  one  median,  and  two  lateral,  containing 
elastic  tissue.  From  the  epiglottis,  to  which  it  is  intimately  ad- 
herent, it  is  continued  backwards  on  either  side  to  the  apices  of 
the  arytenoid  cartilages,  forming  the  afnjteno-epiglottic  folds  which 
bound  the  upper  entrance  into  the  larynx. 

The  mucous  membrane  of  the  larynx  is  remarkable  for  its  acute 
sensibility.  This  is  requisite  to  guard  the  upper  opening  of  the 
larynx  during  the  passage  of  the  food  over  it.  The  larynx  is 
closed  during  the  act  of  deglutition  ;  but  if,  during  this  process, 
anyone  attempt  to  speak  or  laugh,  the  epiglottis  is  raised,  and 
allows  the  food  to  pass,  as  it  is  termed,  the  wrong  way.  As  soon 
as  the  foreign  body  touches  the  mucous  membrane  of  the  larynx, 
a  spasmodic  fit  of  coughing  expels  it. 

The  sub-mucous  tissue  of  the  larynx  is  studded  with  mucous: 
glands.  An  oblong  mass  of  them  lies  in  the  aryteno-epiglottic 
fold,  and  they  are  particularly  numerous  about  the  ventricles  of 
the  larynx.  The  surface  of  the  epiglottis  towards  the  tongue 
is  abundantly  provided  with  them.  Their  ducts  pass  through 
the  epiglottis,  and  may  be  recognised  as  minute  openings  on  ita 
laryngeal  aspect. 

SUPERIOR  This  is  the  opening  through  which  the  larynx 

OPENING  OF  THE  communicates  with  the  pharynx.  Its  outline  ia 
LARYNX.  triangular,  with  its  base  directed  forwards,  and  it 

slopes  from  before  backwards.     Anteriorly  it  is  bounded  by  tha 


FALSE  AND  TRUE  VOCAL  CORDS.  245 

epiglottis,  laterally  by  the  aryteno-epiglottic  folds  and  cuneiform 
cartilages,  posteriorly  by  the  arytenoid  cartilages  and  the  cornicula 
laryngis.  The  apex  presents  the  funnel-shaped  appearance  from 
which  the  arytenoid  cartilages  derive  their  name. 

On  looking  down  through  this  superior  opening  you  see  the 
cavity  of  the  larynx,  which  is  divided  into  an  upper  and  a  lower 
part  by  the  narrow  triangular  fissure,  called  the  glottis,  or  rima 
glottidis ;  so  that  the  upper  part  gradually  narrows  to  this 
chink,  while  the  lower  part  gradually  widens,  and  becomes  con- 
tinuous at  the  lower  border  of  the  cricoid  cartilage  with  the 
trachea. 

The  objects  seen  above  the  rima  glottidis  are,  in  the  middle  line, 
below  the  base  of  the  epiglottis,  a  round  elevation  covered  with 
mucous  membrane  of  a  bright  pink  colour,  termed  the  cushion  of 
the  epiglottis ;  on  each  side  is  an  arched  fold,  the  false  vocal  cords 
with  their  concavity  looking  downwards,  and  forming  the  upper 
boundary  of  a  small  recess,  the  ventricle  of  the  larynx,  leading  into 
a  pouch,  called  the  sacculus  laryngis  ;  below  this,  are  the  two  white 
bands,  the  true  vocal  cords,  which  form  the  boundaries  of  the 
glottis.  The  larynx  below  the  true  vocal  cords  gradually  enlarges, 
and  presents  nothing  calling  for  special  description. 

GLOTTIS,  OK  EIMA       The  rima  glottidis  is  the  triangular  horizontal 
GLOTTIDIS.  opening  between  the  inferior  or  true  vocal  cords. 

Its  apex  is  directed  forwards,  its  base  backwards.  The  anterior 
two-thirds  of  this  opening  is  bounded  by  the  true  vocal  cords,  the 
posterior  third  by  the  arytenoid  cartilages.  The  length  in  the 
male  is  eleven  lines,  its  width  at  rest  from  three  to  four  lines ;  in 
the  female  its  length  is  eight  lines,  its  width  two  lines.  Before 
the  age  of  puberty  these  dimensions  are  much  less. 

SUPERIOR  OR  These    are   the    prominent    crescentic   folds  of 

FALSE  VOCAL  mucous  membrane  which  form  the  upper  boun- 

CoKDS-  daries  of  the  ventricles  and  enclose  within  them 

thin  ligamentous  fibres,  called  the  superior  thyro-arytenoid  ligaments. 
They  are  called  the  false  vocal  cords,  because  they  have  little  or 
nothing  to  do  with  the  production  of  the  voice.  They  are  com- 
posed of  elastic  tissue  like  the  true  vocal  cords ;  but  they  also 
•contain  fatty  tissue,  which  the  true  ones  do  not. 


24G 


THE    GLOTTIS. 


INFERIOR  OR 
TRUE  VOCAL 
CORDS. 


FIG.  55. 


Thyroid  cartilage. 
True  vocal  cord. 


Arytenoid  cartilage. 
Elastic  ligament. 


These  two  cords,  called  also  the  inferior  thyro*. 
arytenoid  ligaments,  are  composed  of  yellow  elastic 
tissue,  and  extend  horizontally  from  the  angle  of 
the  thyroid  cartilage  to  the  anterior  angles  of  the  base  of  the 
arytenoid  cartilages.  Their  inner  or  free  edges  are  thin  and  sharp > 
and  look  upwards ;  their  outer  borders  are  continuous  with  the 
crico-thyroid  membrane,  and  are  in  contact  with  the  thyro-*- 
arytenoidei  muscles.  They  diverge  as  they  pass  backwards,  and 

are  covered  with  very  thin  and 
closely  adherent  mucous  mem-, 
brane,  having  columnar  ciliated 
epithelium.  We  shall  presently 
see  that,  by  the  muscles  which 
act  upon  the  arytenoid  cartilages, 
these  cords  can  be  approximated 
or  separated  from  each  other ;  in 
other  words,  the  rima  glottidis  can 
be  closed  or  dilated.  When  suffi-. 
ciently  tightened,  and  brought 
parallel  by  means  of  certain 

muscles,   the   cords  are  made  to   vibrate  by  the   current   of  the 
expired  air,  and  thus  is  produced  the  voice. 

In  the  adult  male  the  true  vocal  cords  measure  about  seven 
lines ;  in  the  female,  about  five  lines.  In  boys  they  are  shorter ; 
hence  their  peculiar  voice.  At  puberty,  the  cords  lengthen,  and 
the  voice  breaks. 

The  glottis  admits  of  being  dilated,  contracted,  and  even  com- 
pletely closed,  by  its  appropriate  muscles.  When  at  rest,  its  shape 
is  triangular,  as  shown  in  fig.  55,  where  the  arytenoid  cartilages 
are  cut  through  on  a  level  with  the  vocal  cords.  During  every 
inspiration,  the  glottis  is  dilated  by  the  crico-arytenoidei  postici ; 
it  then  becomes  pear-shaped  (fig.  57).  During  expiration,  it  re- 
sumes its  triangular  shape :  and  this  return  to  a  state  of  rest  ia 
effected,  not  by  muscular  agency,  but  by  two  elastic  ligaments, 
shown  in  fig.  55,  which  draw  the  arytenoid  cartilages  together. 
Thus  then  the  glottis,  like  the  chest,  is  dilated  by  muscular  tissue ; 
like  the  chest,  also,  it  is  contracted  by  elastic  tissue.  In  speaking 


SHAPE    OF    THE    GLOTTIS 
WHEN    AT    REST. 


INTRINSIC    MUSCLES    OF   THE    LARYNX. 


247 


or  singing,  the  glottis  assumes  what  is  called  the  vocalising  posi- 
tion— that  is,  the  opening  becomes  narrower,  and  its  edges  nearly 
parallel. 

VENTRICLES  OP          These  are  the  recesses  between  the  upper  and 
THE  LARYNX.  lower  vocal  cords,  and  each  leads  to  a  small  conical 

pouch,  the  sacculus  laryngis.  Each  ascends  for  about  half  an  inch, 
as  high  as  the  upper  border  of  the  thyroid  cartilage,  which  bounds 
it  on  its  outer  side,  while  on  the  inner  side  is  the  upper  vocal 
cord.  It  contains  from  sixty  to  seventy  muciparous  glands.  Over 
its  inner  and  upper  part  is  a  layer  of  muscular  tissue,  compressor 
sacculi  larynyis  of  Hilton  (aryteno-epiglottideus  inferior),  which 
connects  it  with  the  aryteno-epiglottic  fold  ;  on  its  outer  side  is 
the  upper  part  of  the  thyro-arytenoideus. 

INTRINSIC  There  are  eleven  muscles  which  act  upon  the 

MUSCLES  OF  THE  larynx  :  five  on  each  side  and  one  in  the  mid- 
LARYNX.  ^je<  ip^e  gve  pajrs  are — the  crico-thyroidei,  the 

crico-arytenoidei  postici,  the  crico-arytenoidei  laterales,  the  thyro- 
arytenoidei,  and  the  aryteno-epiglottidei.  The  single  one  is  the 
arytenoideus. 

FIG.  56. 


Arytenoid  cartilage  .    . 
Crico-arytenoid  joint     . 

Crico-thyroid  joint    .    . 


Thyroid  cartilage. 

True  vocal  cord. 

Cricoid  cartilage  raised. 
Cricoid  cartilage. 


DIAGRAM    SHOWING    THE    ACTION    OF    THE    CRICO-THYROID    MUSCLE. 


M.  CRICO-  This   muscle    is    situated  on  the  front  of  the 

THYROIDEUS.  larynx.     It  arises  from  the  front  and  side  of  the 


248 


INTRINSIC   MUSCLES    OF  THE   LARYNX. 


cricoid  cartilage,  ascends  obliquely  outwards,  and  is  inserted  into 
the  inferior  border  and  lower  cornu  of  the  thyroid.  Its  action  is 
to  tighten  the  vocal  cords.  It  does  this  by  raising  the  anterior 
part  of  the  cricoid  cartilage  :  since  this  cartilage  cannot  be  raised 
without  lengthening  these  cords,  as  shown  by  the  dotted  line, 
fig.  56.  Its  nerve  is  the  external  laryngeal  branch  of  the  superior 
laryngeal.  Between  the  anterior  borders  of  the  two  muscles  is  seen 
the  crico-thyroid  membrane,  which  is  divided  in  laryngotomy. 
M.  CKICO-  This  muscle  arises  from  the  broad  depression 

on  the  posterior  part  of  the  cricoid  cartilage ;  its 
fibres  converge,  and  pass  outwards  and  upwards, 

FIG.  57. 


ARYTENOIDEUS 
POSTICUS. 


Vocal  cord  .  .  . 
Thyroid  cartilage 
Cricoid  cartilage  . 


Arytenoid  cartilage . 
Elastic  ligament 
(crico-arytenoid)  . 


Thyro-arytenoideus. 


Crico-arytenoideus 

lateralis. 


Ideal  pivot. 


Crico-arvteiioideus 
posticus. 


GLOTTIS    DILATED  :     MUSCLES    DILATING    IT    KEPEESENTED    WAVY. 

to  be  inserted  into  the  outer  angle  of  the  base  of  the  arytenoid. 
Its  action  is  to  dilate  the  glottis.  It  does  this  by  drawing  the 
posterior  tubercle  of  the  arytenoid  cartilage  toivards  the  mesial 
line,  and  therefore  the  anterior  angle  (to  which  the  vocal  cord  is 
attached)  from  the  mesial  line  (fig.  57).  In.  this  movement  the 
arytenoid  cartilage  rotates  as  upon  a  pivot,  and  acts  as  a  lever 
of  the  first  order;  the  fulcrum  or  ideal  pivot  being  interme- 
diate between  the  power  and  the  weight.  This  muscle  dilates  the 
glottis  at  each  inspiration.  Its  nerve  comes  from  the  inferior 
laryngeal.1 

1  A  slip  called  the  '  kerato-cricoid  '  is  occasionally  present.     It   is   a   short 


INTRINSIC   MUSCLES   OF   THE   LARYNX. 


249 


M.  ABYTE- 
NOIDETJS. 


This  single  muscle  is  situated  immediately  at 
the  back  of  the  arytenoid  cartilages.  The  fibres 
pass  across  from  one  cartilage  to  the  other  running  in  a  transverse 
direction.  Action.  —  By  approximating  the  arytenoid  cartilages, 
they  assist  in  contracting  the 
glottis.  It  is  supplied  by  the 
inferior  laryngeal  nerve. 

M.  ARYTENO-  This      muscle 

EPIGLOTTIDEUS.  cvrises  from  the 
inferior  and  outer  angle  of  the 
arytenoid  cartilage,  and,  crossing 
its  fellow  like  the  letter  X,  is 
inserted,  partly  into  the  apex  of 
the  opposite  arytenoid  cartilage, 
and  partly  into  the  aryteno- 
epiglottic  fold. 

T°  expose  this 

reflect 

crico-thyroid 

muscle,  the  crico-thyroid  mem- 
brane, and  then  cut  away  the  ala 
of  the  thyroid  cartilage.  It  arises 
from  the  upper  border  of  the  side 
of  the  cricoid  cartilage,  and  the 
fibres,  passing  backwards  and  up- 
wards, converge  to  be  inserted  into 
the  external  angle  of  the  base  of 
the  arytenoid,  in  front  of  the  crico- 
arytenoideus  posticus.  Action.  — 
By  drawing  the  arytenoid  carti- 
lages inwards,  the  muscles  of  opposite  sides  contract  the  glottis 
(fig.  59).  Its  nerve  comes  from  the  inferior  laryngeal. 


M.  CRICO- 
ARYTENOIDEUS 
LATERALIS. 


SIDE    VIEW    OF    THE    MUSCLES    OF    THE 
LARYNX. 

1.  Thyro-epiglottideus. 

2.  Thyro-arytenoideus,  upper  and  lower 

portions. 

3.  Crico-arytenoideus  lateralis. 

4.  Crico-arytenoideus  postieus. 

5.  Arytenoideus. 


fasciculus  passing  from  the  cricoid  to  be  inserted '  into  the  inferior  cornu  of  the 
thyroid  cartilage.  It  is  in  connection  with  the  crico-arytenoideus  posticus,  and  is 
usually  found  on  one  side  only,  being  present  in  about  one  in  five  subjects. 
(Merkel,  Anat.  und  Phys.des  mensch.  Stimme-und  Sprach-Organs,  1857  ;  Turner, 
Month.  Med.  Journ.,  Feb.  1860). 


250 


INTRINSIC   MUSCLES   OF   THE    LARYNX. 


M.  THYRO- 

ARYTENOIDEUS. 


This  muscle  arises  from  the  side  of  the  angle  of 
the  thyroid  cartilage  and  the  crico-thyroid  mem- 
brane, runs  horizontally  backwards,  and  is  inserted  into  the  base 
and  anterior  surface  of  the  arytenoid.  Its  fibres  run  parallel  with 


FIG.  59. 


Vocal  cord 


Aryteuoid  cartilage 
Elastic  ligament  . 


Thyro-arytenoideus.. 


Crico-arytenoideus 
lateralis. 


Crico-arytenoideus. 
posticus. 


GLOTTIS    CLOSED  :     MUSCLES    CLOSING    IT    REPRESENTED    WAVY. 


the  true  vocal  cord,  and  some  of  them  are  directly  inserted  into  it. 
It  consists  of  two  fasciculi — an  upper  and  a  lower.  The  lower  and 
larger  portion  is  inserted  into  the  anterior  angle  and  the  anterior 
surface  of  the  arytenoid  ;  the  upper  is  inserted  into  the  upper  part 
of  the  anterior  surface  and  the  anterior  border  of  the  arytenoid. 
Its  nerve  comes  from  the  inferior  laryngeal. 

This  muscle  relaxes  the  vocal  cord.  More  than  this,  it  puts, 
the  lip  of  the  glottis  in  the  vocalising  position  ;  in  this  position  the 
margins  of  the  glottis  are  parallel,  and  the  chink  is  reduced  to 
the  breadth  of  a  shilling. 

The  following  table  shows  the  action  of  the  several  muscles, 
which  act  upon  the  glottis  : — 


Crico-thyroidei     .        . 
Thyro-arytenoidei 

Crico-arytenoidei  postici 


Stretch  the  vocal  cords. 

Relax  the  vocal  cords,  and  place  them  in  the 

vocalising  position. 
Dilate  the  glottis. 


VESSELS  AND  NERVES  OF  THE  LARYNX.  251 

Crico-arytenoidei  laterales  .  Draw  together  the  arytenoid  \ 

cartilages  rc  °*e 

Arytenoideus      .        .        .    Ditto        ditto        ditto          j    ° 
Aryteno-epiglottidei    .        .    Contract  the  upper  opening  of  the  larynx. 

The  epiglottis  is  connected  by  muscles  with  the  arytenoid  and 
thyroid  cartilages :  they  are  the  thyro-epiglottideus,  the  aryteno- 
epiglottideus  superior  and  inferior. 

The  thyro-epiglottideus  is  a  thin  muscle,  arising  from  the  angle 
of  the  thyroid  cartilage  just  above  the  thyro-arytenoideus,  and  is 
inserted  by  diverging  fibres  into  the  border  of  the  epiglottis  and 
into  the  aryteno-epiglottic  fold. 

The  aryteno-epiglottideus  superior  passes  as  thin  muscular  fibres 
from  the  tip  of  the  arytenoid  cartilage  to  the  mucous  membrane 
attached  to  the  side  of  the  epiglottis. 

The  aryteno-epiglottideus  inferior,  separated  from  the  preceding 
by  a  distant  interval,  arises  from  the  anterior  surface  of  the  ary- 
tenoid cartilage,  and  is  inserted  into  the  upper  and  inner  part  of 
the  epiglottis.  This  muscle  is  also  called  the  compressor  saceuli 
laryngis  of  Hilton.1 

The  Mood-vessels  of  the  larynx  are  derived  from  the  superior  and 
inferior  thyroid  arteries.  The  laryngeal  branch  of  the  superior 
thyroid  passes  through  the  thyro-hyoid  membrane  with  the 
corresponding  nerve,  and  divides  into  branches,  which  supply  the 
muscles  and  the  mucous  membrane.  The  laryngeal  branches  of  the 
inferior  thyroid  ascend  behind  the  cricoid  cartilage.  A  constant 
little  artery  passes  through  the  crico-thyroid  membrane. 

The  nerves  of  the  larynx  are  the  superior  and  inferior  (recurrent) 
laryngeal  branches  of  the  pneumogastric. 

The  superior  laryngeal,  having  passed  through  the  thyro-hyoid 
membrane,  divides  into  branches,  distributed  to  the  mucous  mem- 
brane of  the  larynx.  Its  filaments  spread  out  in  various  directions  : 
some  to  the  anterior  and  posterior  surfaces  of  the  epiglottis,  and  to 
the  aryteno-epiglottidean  folds,  others  to  the  interior  of  the  larynx 
and  the  vocal  cords.  A  constant  filament  descends  behind  the  ala 

1  The  triticeo-glossus  is  a  small  muscle  frequently  present :  it  arises  from  the 
cartilage  triticea,  and  passing  forwards  and  upwards  joins  the  cerato-glossus  to  be 
inserted  into  the  tongue. 


252  DIFFERENCES  BETWEEN  THE  MALE  AND  FEMALE  LARYNX. 

of  the  thyroid  cartilage,  and  communicates  with  the  inferior  laryn- 
geal,  and  another  communication  with  the  same  nerve  is  found 
behind  the  larynx  beneath  the  pharyngeal  mucous  membrane.  Its 
external  laryngeal  branch  supplies  the  crico-thyroid  muscle. 

The  inferior  (or  recurrent}  larynyeal  nerve  enters  the  larynx  be- 
neath the  inferior  constrictor,  and  ascends  behind  the  joint  between 
the  thyroid  and  cricoid  cartilages.  It  supplies  all  the  intrinsic 
muscles  of  the  larynx  except  the  crico-thyroid.  If  the  recurrent 
nerve  be  divided,  or  in  any  way  injured,  the  muscles  moving  the 
glottis  become  paralysed,  but  its  sensibility  remains  unimpaired. 
When  the  nerve  is  compressed  by  a  tumour — for  instance,  an 
aneurism  of  the  arch  of  the  aorta — the  voice  is  changed  to  a 
whisper,1  or  even  lost. 

DIFFEEENCE  Until  the  approach  of  puberty,  there  is  no  great 

BETWEEN  THE  MALE  difference   in   the    relative  size  of  the  male  and 

AND  THE  FEMALE       female  larynx.     The  larynx  of  the  male,  within 

AKYNX'  two  years  after  this  time,  becomes  nearly  doubled 

in  size ;  that  of  the  female  grows,  but  to  a  less  extent. 

The  larynx  of  the  adult  male  is  in  all  proportions  about  one 
third  larger  than  that  of  the  adult  female. 

The  alee  of  the  thyroid  cartilage  form  a  more  acute  angle  in  the 
male  ;  hence  the  greater  projection  of  the  pomum  Adami  and  the 
greater  length  of  the  vocal  cords  in  the  male. 

(  Male  7  lines 

The  average  length  of  the  vocal  cords  is  in  the  J 

(Female         .5      ,, 

(Mnlp  11 

The  average  length  of  the  glottis  is  in  the    .      J 

(Female          .8     ,, 

The  size  of  the  larynx  does  not  necessarily  follow  the  propor- 
tions of  the  general  stature ;  it  may  be  as  large  in  a  little  person 
as  in  a  tall  one  :  this  corresponds  with  what  we  know  of  the 
voice. 

1  Medical  Gazette,  Dec.  1843. 


THE    TONGUE.  253 


DISSECTION   OF   THE   TONGUE. 

The  tongue  is  a  complex  muscular  organ,  subservient  to  taste, 
speech,  suction,  mastication,  and  deglutition.  It  is  situated  in  the 
space  formed  by  the  lower  dental  arch ;  its  upper  surface  is  convex 
and  free,  as  is  also  its  anterior  part  or  tip,  which  lies  behind  the 
lower  incisor  teeth  ;  its  posterior  and  inferior  part  is  connected  to 
the  os  hyoides  by  the  hyo-glossi,  to  the  styloid  process  of  the  tem- 
poral bone  by  the  stylo-glossi,  and  to  the  symphysis  of  the  lower 
jaw  by  the  genio-hyo-glossi  muscles. 

The  upper  surface  or  dorsum  is  convex,  and  slopes  on  all  sides 
from  the  centre ;  it  is  divided  into  two  symmetrical  halves  by  a 
median  groove — rapJie — running  along  the  middle,  and  terminates 
posteriorly  in  a  depression — the  foramen  ccecum — into  which  open 
several  mucous  glands.  The  posterior  third  of  the  dorsum  is  com- 
paratively smooth  :  the  anterior  two-thirds  is  rough,  and  covered 
with  small  eminences  called  papillce. 

Mucous  MEM-  The  surface  of  the  tongue  is  covered  with  mu- 

BRANE.  cous  membrane,  which  is  composed  of  structures 

similar  to  those  of  the  skin  generally — that  is  to  say,  it  consists  of 
a  cutis  vera  with  numerous  elevations  called  papillae,  and  of  a  thick 
layer  of  squamous  epithelium.  The  cutis  is  much  thinner  than 
that  of  the  skin  of  the  body,  and  affords  insertion  to  some  muscular 
fibres  of  the  tongue. 

The  mucous  membrane  on  the  under  aspect  of  the  tongue  is 
smooth  and  comparatively  thin,  and,  in  the  middle  line  in  front, 
forms  a  fold — the  frcenum  linguce — which  connects  it  to  the  mucous 
membrane  of  the  floor  of  the  mouth.  On  each  side  of  the  fraenum 
are  the  elevated  orifices  of  the  submaxillary  ducts ;  and  further 
back,  in  the  furrow  between  the  tongue  and  gums,  are  the  openings 
of  the  sublingual  ducts.  Laterally,  the  mucous  membrane  is  re- 
flected from  the  under  part  of  the  tongue  to  the  lower  jaw,  and 
forms  the  floor  of  the  mouth. 

From  the  posterior  part  of  the  tongue  the  mucous  membrane 
passes  to  the  soft  palate  on  each  side,  forming  the  folds  termed  the 


254 


THE    TONGUE. 


FIG.  60. 


anterior  palatine  arches,  which  enclose  the  palato-glossi ;  there  are 
also  three  folds  to  the  epiglottis,  termed  the  glosso-epiglottic  :  two 
lateral  and  one  median,  the  latter  enclosing  a  layer  of  elastic  tissue 
called  the  glosso-epiglottic  ligament.  This  ligament  raises  the 
epiglottis  when  the  tongue  is  protruded  from  the  mouth ;  hence 
the  rule  of  never  pulling  the  tongue  forwards  when  passing^  a 
tube  into  the  oesophagus,  otherwise  the  tube  might  pass  into  the 
larynx. 

PAPILLA  OF  The  anterior  two-thirds  of  the  tongue  is  studded 

THE  TONGUE.  with  numerous   small   eminences  called  papillae, : 

these,  according  to  their  size  and  form,  are 
distinguished  into  three  kinds — viz.  papil- 
lae circumvallatce,  papillce  fungiformes,  and 
papillce  filiformes  (fig.  60). 

The  papillce  circumvallatce  vary  in  number 
from  eight  to  twelve,  and  are  arranged  at 
the  back  of  the  tongue  in  two  rows,  which 
converge  like  the  branches  of  the  letter  V, 
with  the  apex  backwards,  towards  the  for- 
amen caecum.  Each  of  these  papillae  is 
circular,  from  the  -^th  to  -^In.  °^  an  incn 
wide,  and  slightly  broader  above  than  below. 
Each  is  surrounded  by  a  circular  fossa, 
which  itself  is  bounded  by  an  elevated  ring 
(vallum') .  The  papillae  are  covered  with  a 
thick  stratum  of  scaly  epithelium,  beneath 
which  are  numerous  secondary  papillae. 
Buried  in  the  epithelium  surrounding  the 
sides  (but  not  on  the  upper  surface)  of 
these  papillae,  numerous  flask-shaped  bodies, 
called  the  taste-buds,  have  been  discovered. 
Their  bases  rest  upon  the  corium,  and  their  apices  open  upon 
the  surface.  Each  consists  of  a  cortical  and  a  medullary  portion : 
the  cortical  is  made  up  of  one  or  more  layers  of  long  flattened 
cells  ;  the  central  consists  of  numerous  spindle-shaped  cells,  whose 
free  extremity  projects  from  the  orifice  of  the  taste-bud,  while  the 
deeper  extremity  rests  in  the  corium,  and  is  in  close  connection. 


UPPEK  SURFACE  OF  THE 
TONGUE,  WITH  THE  FAUCES 
AND  TONSILS. 

1.  Papillae  circumvallatse. 

2.  Papillae  f  ungiformes. 


PAPILLAE    OF   THE    TONGUE.  255 

with  a  fine  plexus  of  nerve-filaments  derived  from  the  glosso- 
pharyngeal  nerve.1 

The  papillce  fungifarmes,  smaller  and  more  numerous  than  the 
circumvallatce,  are  scattered  chiefly  over  the  sides  and  tip  of  the 
tongue,  and  sparingly  over  its  upper  surface.  They  vary  in  shape, 
some  being  cylindrical,  others  having  rounded  heads  like  mush- 
rooms :  whence  their  name.  Near  the  apex  of  the  tongue  they 
may  be  distinguished  during  life  from  the  other  papillae  by  their 
redder  colour.  In  scarlatina,  and  some  exanthematous  fevers, 
these  papillae  become  elongated,  and  of  a  bright  red  colour ;  as  the 
fever  subsides,  their  points  acquire  a  brownish  tint,  giving  rise  to 
what  is  called  the  strawberry  tongue. 

The  papillce  filiformes  (conicce)  are  the  smallest  and  most 
numerous.  They  are  so  closely  aggregated  that  they  give  the 
tongue  a  velvet-like  appearance.  Their  points  are  directed  back- 
wards, so  that  the  tongue  feels  smooth  if  the  finger  be  passed  over 
it  from  apex  to  base,  but  rough  if  in  the  contrary  direction.  These 
papillae  consist  of  small  conical  processes  arranged  for  the  most 
part  in  a  series  of  lines  running  parallel  to  the  two  rows  of  the 
papillae  circumvallatas.  Each  papilla  is  covered  with  a  thick  layer 
of  epithelium,  which  is  prolonged  into  a  number  of  free  hair-like 
processes. 

If  the  papillae  be  injected,  and  examined  under  the  microscope, 
it  is  found  that  they  are  not  simple  elevations,  like  those  of  the 
skin,  but  that  from  them  arise  secondary  papillae.  The  papillae 
circumvallatae  consist  of  an  aggregation  of  smaller  papillae  arranged 
parallel  to  each  other ;  and  the  papillae  fungiformes  consist  of  cen- 
tral stems  from  which  minute  secondary  papillae  shoot  off.  This 
elaborate  structure  escapes  observation  because  it  is  buried  beneath 
the  epithelium.2  Each  secondary  papilla  receives  a  blood-vessel, 
which  passes  nearly  to  its  apex,  and  returns  in  a  loop-like  manner. 

The  papillae  are  covered  with  one  or  more  layers  of  squamous 
epithelium.  That  which  covers  the  filiform  is  superimposed  so 

1  For  further  information  about  these  bodies  the  student  is  referred  to 
Engelmann  in  Strieker's  Handbook.  He  states  that  each  taste-bud  consists  of 
from  fifteen  to  thirty  cells. 

*  See  Bowman  and  Todd's  Physiological  Anatomy. 


256  GLANDS  BENEATH  THE  TONGUE. 

thickly  as  to  give  it  sometimes  the  appearance  of  a  brush  when 
seen  under  the  microscope.  The  various  kinds  of  fur  on  the 
tongue  consist  of  thick  and  sodden  epithelium. 

Respecting  the  use  of  the  papillse,  it  is  probable  that  they 
enable  the  tongue  to  detect  impressions  with  greater  delicacy. 
From  the  density  and  arrangement  of  their  epithelial  coat,  the 
filiform  papillas  give  the  surface  of  the  tongue  a  roughness,  which 
is  useful  in  its  action  upon  the  food.  An  apparatus  of  this  kind, 
proportionately  stronger  and  more  developed,  makes  the  tongue  of 
ruminant  animals  an  instrument  by  which  they  lay  hold  of  their 
food.  In  the  feline  tribe — e.g.  the  lion  and  tiger — these  papillae 
are  so  sharp  and  strong  that  they  act  like  rasps,  and  enable  the 
animal  to  lick  the  periosteum  from  the  bones  by  a  single  stroke  of 
his  tongue.  In  some  mammalia,  they  act  like  combs  for  cleaning 
the  skin  and  the  hair. 

Numerous  small  racemose  and  acino-tubular 
glands,  lingual  glands,  are  found  in  the  sub- 
mucous  tissue  at  the  root  of  the  tongue.  They  are  similar  in 
structure  and  secretion  to  the  tonsillar  and  palatine  glands,  so  that 
there  is  a  complete  ring  of  glands  round  the  isthmus  faucium. 
Small  round  orifices  upon  their  surface  indicate  the  termination  of 
their  ducts.  Other  mucous  glands,  with  ducts  from  one  quarter  to 
half  an  inch  long,  are  situated  in  the  muscular  substance  of  the 
tongue. 

LYMPHOID  A  considerable    amount    of  lymphoid   tissue  is 

TISSUE.  situated  at  the  back  of  the  tongue,  which  in  some 

parts  is  collected  into  definite  masses  called  follicles.  Small  de- 
pressions also  occur  in  this  situation,  whose  walls  are  studded  with 
lymphoid  tissue,  and  into  which  some  of  the  mucous  glands  open. 

On  the  under  surface  of  the  apex  of  the  tongue 
GLANDS  BE- 
NEATH THE  is  placed,  on  either  side,  a  group  of  glands  pre- 

APEX  OF  THE  sumed  to  be  salivary.     Considering  each  group  as 

TONGUE.  one  gigjy^  observe  that  it  is  oblong,  with  the  long 

diameter  from  seven  to  ten  lines,  parallel  with  the  axis  of  the 
tongue.  It  lies  near  the  mesial  line,  a  little  below  the  ranine 
artery,  on  the  outer  side  of  the  branches  of  the  gustatory  nerve, 
under  some  of  the  fibres  of  the  stylo-glossus.  Four  or  five  ducts 


INTRINSIC   MUSCLES   OF  THE   TONGUE.  257 

proceed  from  each  group,  and  terminate  by  separate  orifices  on  the 
under  surface  of  the  tongue. 

MUSCULAR  The  substance   of  the  tongue  is  composed  of 

FIBBKS  OF  THE  muscular  fibres  and  of  a  small  quantity  of  fat.  The 
TONGUE.  extrinsic  muscles  of  the  tongue  have  been  described 

in  the  dissection  of  the  submaxillary  region  (p.  102).  We  have 
now  to  examine  its  intrinsic  muscles.  For  this  purpose  the  mucous 
membrane  must  be  removed  from  the  dorsum  of  the  tongue.  On 
dissection  it  will  be  found  that  the  great  bulk  of  the  organ  consists 
of  fibres  which  proceed  in  a  longitudinal  direction,  constituting  the 
linguales  muscles. 

The  superficial  lingualis  runs  longitudinally  beneath  the  mucous 
membrane  of  the  dorsum  ;  its  fibres  are  attached  posteriorly  to  the 
hyoid  bone  and  run  forwards  to  the  front  and  margin  of  the 
tongue.  Posteriorly  the  muscle  is  thin  and  is  covered  by  the 
fibres  of  the  palato-glossus  and  hyo-glossus. 

The  inferior  lingualis  is  larger  than  the  preceding,  and  is 
situated  on  the  under  aspect  of  the  tongue  between  the  genio-hyo- 
glossus  and  the  hyo-glossus.  It  may  be  readily  exposed  by  dis- 
secting the  under  surface  of  the  tongue  immediately  on  the  outer 
aspect  of  the  genio-hyo-glossus.  It  arises  posteriorly  from  the 
hyoid  bone  and  the  substance  of  the  tongue,  and  its  fibres  pass 
forwards  to  the  tip  of  the  tongue  after  being  reinforced  by  fibres 
from  the  stylo-glossus.  On  its  under  aspect  it  is  in  relation  with 
the  ranine  artery. 

The  transverse  fibres  form  a  considerable  part  of  the  thickness 
of  the  tongue  and  arise  from  the  fibrous  septum.  They  pass  out- 
wards between  the  superficial  and  inferior  linguales,  ascending  as 
they  near  the  sides  of  the  tongue,  where  the  fibres  become  con- 
tinuous with  those  of  the  palato-glossus.  A  considerable  amount 
of  fat  is  found  among  these  fibres. 

The  vertical  fibres  run  in  a  curved  direction,  descending  from 
the  dorsum  to  the  under  aspect  of  the  tongue,  with  the  concavity 
outwards.  They  interlace  with  the  transverse  fibres  and  with  the 
genio-hyo-glossus. 

On  tracing  the  genio-hyo-glossi  into  the  tongue,  we  find  that 
some  of  their  fibres  ascend  directly  to  the  surface ;  others  cross  in 

s 


258  DISSECTION   OF   THE   SUPERIOR   MAXILLARY   NERVE. 

the  middle  line,  intersect  the  longitudinal  fibres,  and  finally  termi- 
nate upon  the  sides  of  the  tongue.  Lastly,  the  fibres  of  the  stylo- 
glossi  should  be  traced  along  the  side  of  the  tongue  to  the  apex. 

FIBBOXJS  SEPTUM  The  fibrous  septum  of  the  tongue  is  a  vertical 
OF  THE  TONGUE.  plane  of  fibrous  tissue  which  extends,  in  the 
mesial  line,  from  the  base  to  the  apex.  It  is  thick  posteriorly, 
where  it  is  connected  behind  with  the  hyoid  bone,  and  is  lost  in 
front  between  the  muscles.  In  it  is  sometimes  found  a  piece  of 
fibro-cartilage,  called  nucleus  fibrosus  linguce,  a  representative  of 
the  lingual  bone  in  some  of  the  lower  animals. 

The  arteries  supplying  the  tongue  are  the  dorsal  and  ranine 
branches  of  the  lingual  artery.  It  is  important  to  bear  in  mind 
that  the  arteries  do  not  anastomose  across  the  middle  line,  and 
only  very  slightly  at  the  apex,  so  that  it  is  possible  to  cut  along 
the  septum  of  the  tongue  from  the  apex  to  the  base  with  very  little 
haemorrhage, — a  fact  of  much  importance  in  the  removal  of  the 
tongue  or  cancer  of  that  organ. 

The  nerves  to  the  tongue  should  now  be  followed  to  their  ter- 
mination. The  hypoglossal  supplies  with  motor  power  all  the 
muscles.  The  gustatory  or  lingual  branch  of  the  inferior  division 
of  the  fifth  is  distributed  to  the  mucous  membrane  and  papillae  of 
the  apex  and  sides  of  the  tongue,  supplying  the  anterior  two-thirds 
with  common  sensation.  Upon  this  nerve  depends  the  sensation 
of  all  ordinary  impressions,  such  as  that  of  hardness,  softness,  heat, 
cold,  and  the  like. 

The  glosso-pharyngeal  nerve  supplies  the  mucous  membrane  at 
the  back  and  the  sides  of  the  tongue,  and  the  papillae  circum- 
vallatae.  Under  the  microscope  small  ganglia  may  be  distin- 
guished on  the  terminal  fibres  of  this  nerve. 


DISSECTION   OF   THE   SUPERIOR  MAXILLARY   NERVE. 

To  trace  this  nerve  and  its  branches  we  must  remove  the  outer 
wall  of  the  orbit  as  far  as  the  foramen  rotundum,  so  as  to  expose 
the  spheno-maxillary  fossa. 

The   superior  maxillary  nerve  is  a  sensory  nerve,  and  is  the 


SUPERIOR  MAXILLARY   NERVE. 


259 


second  division  of  the  fifth  cranial  nerve.  Proceeding  from  the 
Gasserian  ganglion  (fig.  61),  it  leaves  the  skull  through  the  fora- 
men rotundum,  and  passes  horizontally  forwards  across  the  spheno- 
maxillary  fossa.  It  then  passes  into  the  orbit  through  the  spheno- 


FIG.  61. 


Trunk  of  the 
fifth  nerve  . 

•Qasserian  ) 
ganglion  .  | 


Facial  n 


'Chorda  tym- 
pani    .    . 


Submaxillary 
ganglion  . 


Frontal,  lachry- 
mal and  na-Ki! 
nn. 

Orbital  branch. 


Infra-orbital  n. 


Anterior  dental  n. 

Xaso-palatine  n. 
Palatine  n. 


Gustatory  n. 


DIAGBAM    OF    THE    SUPERIOR   MAXILLARY    NERVE. 

1.  Spheno-palatine  ganglion.  2.  Otic  ganglion. 

maxillary  fissure,  enters  the  infra-orbital  canal  with  the  corre- 
sponding artery,  and  finally  emerges  upon  the  face,  through  the 
infra-orbital  foramen,  beneath  the  levator  labii  superioris,  where  it 
divides  into  a  number  of  spreading  branches,  distributed  to  the 
lower  eyelid,  the  nose  and  the  upper  lip.  The  branches  given  off 
are : — 

1.  Within  the  skull. 

a.  A  recurrent  branch,  to  the  dura  mater  and  the  middle  meningeal 
artery,  is  given  off  near  the  Gasserian  ganglion. 

2.  In  the  spheno-maxillary  fossa. 

b.  The  orbital  branch  already  described  (p.  63). 

c.  Two  spheno-palatine  branches  which  descend  to  the  spheno-pala- 
"tine  ganglion  (Meckel's),  situated  in  the  spheno-maxillary  fossa  (fig.  61). 

d.  The  dental  branches  are  three  in  number  :  the  two  posterior  are 

s  2 


2GO  SPHENO-PALATINE   GANGLION. 

given  off  immediately  before  the  nerve  enters  the  infra-orbital  canal, 
and  descend  along  the  tuberosity  of  the  superior  maxillary  bone  ;  the- 
anterior  is  given  off  in  the  infra-orbital  canal.  The  posterior  branch 
divides  into  two  branches,  which  send  small  filaments  to  the  gums  and 
the  mucous  membrane  of  cheek,  and  then  run  in  bony  canals  in  company 
with  small  arteries  to  supply  the  molar  teeth  and  the  antrum  ;  the 
middle  branch  passes  down  in  a  special  canal  in  front  of  the  antrum  to 
be  distributed  to  the  bicuspid  teeth  ;  the  anterior  branch,  the  largest, 
is  given  off  before  the  nerve  emerges  from  the  infra-orbital  foramen, 
and  enters  the  canal  in  the  front  wall  of  the  antrum  ;  it  divides  into 
dental  branches  for  the  supply  of  the  canine  and  incisor  teeth,  and  into 
a  nasal  branch  for  the  mucous  membrane  of  the  floor  of  the  nasal  fossa. 
The  anterior  branch  while  in  its  bony  canal  gives  off  some  filaments, 
which  join  with  the  posterior  dental  branches,  and  above  the  canine 
fossa  it  also  forms  a  communication  with  a  nasal  branch  from  the 
spheno-palatine  ganglion,  to  form  the  ganylion  of  Boclidalek. 

e.  The  terminal  branch  of  the  superior  maxillary  nerve  is  called  the 
infra-orbital,  which  divides  on  the  face  into  palpebral,  nasal,  and  labial 
branches.  These  have  been  already  dissected  and  described  (p.  48). 

At  this  stage  the  student  should  make  the  dis- 
section to  expose  the  spheno-palatine  ganglion  and 
its  branches.  To  do  this,  it  is  necessary  to  saw  through  the  skull 
rather  on  one  side  of  its  middle  line,  so  as  to  expose  the  cavity  of  the 
nose.  Search  must  now  be  made  for  the  spheno-palatine  foramen 
(just  external  to  which  is  the  spheno-palatine  ganglion),  which  is 
situated  immediately  above  the  posterior  extremity  of  the  middle 
turbinated  bone.  Remove  the  mucous  membrane  at  this  point,  when 
the  terminal  branch  of  the  internal  maxillary  artery,  which  comes 
through  this  foramen  into  the  nose,  may  be  readily  made  out.  The 
student  should  next  cut  away  the  thin  plate  of  bone  which  forms 
the  inner  boundary  of  the  posterior  palatine  canal.  Then,  by 
tracing  upwards  the  branches  contained  within  the  canal,  he  will 
find  the  ganglion. 

SPHENO-PALA-  This  ganglion   is    called,    after   its    discoverer, 

TINE  GANGLION.  Meckel's  ganglion.  It  is  the  largest  of  the  ganglia 
in  connection  with  the  branches  of  the  fifth  cerebral  nerve,  is  tri-* 
angular,  convex  on  its  outer  surface,  of  reddish-grey  colour,  about 
one-fifth  of  an  inch  in  diameter,  and  is  placed  immediately  below 


SFHENO-rALATINE   GANGLION. 


261 


the  superior  maxillary  nerve,  as  it  crosses  the  spheno-maxillary 
fossa.  Like  other  ganglia,  it  has  three  roots — a  sensory,  from  the 
superior  maxillary  ;  a  motor,  from  the  great  petrosal  branch  of  the 
facial ;  and  a  sympathetic,  from  the  carotid  plexus. 


FIG.  62. 


15 
DEEP    VIEW    01'    THE    SPHENO-PALATINE    GANGLION,    AND    ITS    CONNECTION    WITH    OTHER 

NEEVES.     (After  Hirschfeld.) 


1.  Superior  maxillary  n. 

2.  Spheno-palatine  ganglion,  from  the  lower  part 

of  which  are  seen  proceeding  the  palatine 
nerves. 

3.  Posterior  superior  dental  brs. 

4.  Sixth  n.  receiving  two   filaments  from  the 

carotid  plexus  of  the  sympathetic  n. 
6.  The  carotid  br.  of  the  Vidian. 

6.  The  great  petrosal  br.  of  the  Vidian. 

7.  Lesser  petrosal  nerve. 

8.  External  deep  petrosal  n.,  uniting  with  lesser 

petrosal  n. 


9.  The  internal  deep  petrosal  nerve  joining  the 
great  petrosal  nerve. 

10.  Filament  to  fenestra  ovalis. 

11.  Filament  to  Eustachian  tube. 

12.  Filament  to  fenestra  rotunda. 

13.  Chorda  tympani. 

14.  Infra-orbital  nerve. 

15.  Anterior  dental  n. 

16.  Junction  of  posterior  and  anterior  dental 

filaments. 

17.  Grlosso-pharyngeal  n.   giving    off   tymj  anic 

branch. 


Its  branches  pass  upiuards  to  the  orbit,  downwards  to  the  palate, 
inivards  to  the  nose,  and  backivards  to  the  pharynx,  as  follows : — 

a.  Ascending  branches. — These  are  very  small,  and  run  through  the 
spheno-maxillary  fissure  to  be  distributed  to  the  periosteum  of  the 
orbit.1 

1  Anatomists  describe  several  branches  ascending  from  the  ganglion :  one  to 
join  the  sixth  nerve  (Bock);  another  to  join  the  ophthalmic  ganglion  (Tiedemann); 
and,  lastly,  some  to  join  the  optic  nerve  through  the  ciliary  branches  (Hirzel). 


262  SPHENO-PALATINE    GANGLION. 

b.  Descending  branches. — To  see  these  the  mucous  membrane  must 
be  removed  from  the  back  part  of  the  nose  :  we  shall  then  be  able  to 
trace  the  nerves  through  their  bony  canals.     Their  course  is  indicated 
by  their  accompanying  arteries.     They  descend  through  the  palatine 
canals,  and   are  three  in  number.     The  anterior  palatine  nerve,  the 
largest,  descends  through  the  posterior  palatine  canal  to  the  roof  of  the 
mouth,  and  then  divides  into  branches,  which  run  in  grooves  in  the 
hard  palate  nearly  to  the  gums  of  the  incisor  teeth,  where  it  communi- 
cates with  the  naso-palatine  nerve.     Within  its  canal  it   sends   two 
inferior  nasal  branches  which  enter  the  nose  through  foramina  in  the 
palate  bone  to  supply  the  membrane  on  the  middle  and  lower  spongy 
bones.     The  posterior  or  smaller  palatine  descends  in  the  same  canal 
with  the  anterior,  or  in   a  smaller  one  of  its  own,  and  supplies  the 
mucous  membrane  of   the  soft   palate,    the  tonsil,  and   (according  to 
Meckel)  the  levator  palati   muscle.1     The  external  palatine   may   be 
traced  in  a  special  canal  down  to  the  soft  palate,  where  it  terminates  in 
branches  to  the  uvula,  the  palate,  and  tonsil.     The  two  last  branches 
communicate  with  the  tonsillar  filaments  of  the  glosso-pharyngeal  to 
form  the  tonsillar  plexus  of  nerves. 

c.  Internal  branches. — These,  three  or  four  in  number,  pass  through 
the  spheno-palatine  foramen  to  the  mucous  membrane  of  the  nose.     To 
see  them  clearly,  the  parts  should  have  been  steeped  in  dilute  nitric 
acid  ;  afterwards,  when  well  washed,  these  minute  filaments  may  be 
recognised  beneath  the  mucous  membrane  covering  the  spongy  bones. 
The  upper  nasal  branches,  four  or  five  in  number,  pass  inwards,  and  are 
distributed  on  the  two  upper  spongy  bones,  the  upper  and  back  part  of 
the  septum  and  the  posterior  ethmoidal  cells.     The  naso-palatine  (nerve 
of  Cotunnius),  traverses  the  roof  of  the  nose,  distributes  branches  to  the 
back  part  of  the  septum  narium,  and  then  proceeds  obliquely  forwards, 
along  the  septum,  to  the  foramen  incisivum,  through  which  it  passes, 
and  finally  terminates  in  the  palate  behind  the  incisor  teeth,  communi- 
cating here  with  the  anterior  palatine  nerve. 

d.  Posterior   branches. — The  pharyngeal  nerve    (ptery go-palatine), 
very  small,  comes  off  from  the  back  of  the  ganglion,  and,  after  passing 

1  According  to  Longet  (Anat.  et  Physiol.  dzt  Systeme  Nerveux,  Paris,  1842),. 
the  posterior  palatine  nerve  supplies  the  levator  palati  and  the  azygos  uvulas  with 
motor  power.  In  this  view  of  the  subject  the  nerve  is  considered  to  be  the  con- 
tinuation or  terminal  branch  of  the  motor  root  of  the  ganglion :  that,  namely, 
derived  from  the  facial.  This  opinion  is  supported  by  cases  in  which  the  uvula 
is  stated  to  have  been  drawn  on  one  side  in  consequence  of  paralysis  of  the  oppo-. 
site  facial  nerve. 


OTIC   GANGLION.  263 

through  the  pterygo-palatine  canal  with  its  corresponding  artery,  .sup- 
plies the  mucous  membrane  of  the  back  of  the  pharynx  and  the  Eusta- 
chian  tube.  The  Vidian  nerve  is  the  principal  branch.  It  proceeds 
backwards  from  the  posterior  part  of  the  ganglion,  through  the  Vidian 
canal,  where  it  distributes  small  branches  to  the  back  part  of  the  roof 
of  the  nose  and  septum.  It  then  traverses  the  fibro-cartilage  of  the 
foramen  lacerum  medium,  and  divides  into  two  branches.  Of  these  two 
branches,  one,  the  larger — the  carotid — joins  the  sympathetic  plexus 
on  the  outer  side  of  the  internal  carotid  artery ;  the  other,  the  great 
petrosal,  enters  the  cranium,  and  runs  beneath  the  Gasserian  ganglion 
and  the  dura  mater  in  a  small  groove  on  the  anterior  surface  of  the 
petrous  bone  :  it  then  enters  the  hiatus  Fallopii,  and  joins  the  facial 
nerve  in  the  aquseductus  Fallopii. 

It  would  seem  to  be  more  in  accordance  with  modern  views  to  regard 
the  Vidian  nerve,  not  as  dividing  to  form  the  carotid  and  great  super- 
ficial petrosal  branches,  but  rather  as  formed  by  the  junction  of  these 
branches.  In  this  view,  the  Vidian  runs,  not  from,  but  to,  the  spheiio- 
palatine  ganglion. 

The  otic  ganglion  (Arnold's  *)  is  situated  on  the 
OTIC  GANGLION.      .  .,       ,,   ,      .    ,,    .  .,,          ,.    .  .          _      • 

inner  side  ot  the  interior  maxillary  division  01  the 

fifth  nerve,  immediately  below  its  exit  through  the  foramen  ovale 
(fig.  62).  It  is  oval,  of  reddish-grey  colour,  and  always  small.  Its 
inner  surface  is  in  contact  with  the  circumflexus  palati  muscle  and 
the  cartilage  of  the  Eustachian  tube ;  behind  it,  is  the  middle  menin- 
geal  artery  ;  externally,  it  is  in  relation  with  the  inferior  maxillary 
nerve,  where  the  motor  root  joins  the  sensory  root. 

This  ganglio«n  has  branches  of  connection  with  other  nerves ; 
namely,  a  sensory  from  the  auriculo-temporal  nerve ;  a  motor  from 
the  branch  of  the  inferior  maxillary,  which  goes  to  the  internal 
pterygoid  muscle ;  and  a  sympathetic  from  the  plexus  around  the 
arteria  meningea  media.  It  communicates  also  with  the  facial  and 
the  glosso-pharyngeal  nerves  by  the  lesser  petrosal  nerve.  This 
branch  passes  backwards,  either  through  the  foramen  ovale  or  the 
foramen  spinosum,  or  through  a  small  hole  between  them,  and  runs 
beneath  the  dura  mater  in  a  minute  groove  on  the  petrous  bone, 
external  to  that  for  the  great  petrosal  nerve.  Here  it  divides  into 
two  filaments,  one  of  which  joins  the  facial  nerve  in  the  aquseductus 

1  J.  Arnold,  Diss.  Inaug.  Med.,  &c.     Heidelbergas,  1826. 


264 


DIAGRAM    OF   NERVE-COMMUNICATIONS. 


Fallopii ;  the  other  joins  the  tympanic  branch  of  the  glossc-pharyn- 
geal.     These  nerves  are  difficult  to  trace,  not  only  on  account  of 


FIG.  63. 


N.  to  great  petrosal .    . 
N.  to  lesser  petrosal .    . 

N.  to  Eustachian  tube  . 
Ns.  to  carotid  plexus   . 

Chorda  tympani  .    .    . 
N.  to  stylo-hyoid      .    . 

N.  to  (ligastricus      .    . 
Petrous  ganglion     .    . 

Carotid  plexus     .    .    . 

Branch   to  pharyngeal 
plexus 

Lingual  branch    .    .    . 
Ganglion  of  the  trunk  . 


Pharyngeal  n.      . 


Superior  laryugeal 


Gangliform  enlarge- 
ment. 

N.  to  fenestra  ovalis. 

N.  to  fenestra  ro- 
tunda. 

Tympanic  n. 


Auricular  n. 
Glosso-pharyngoal  n. 

Jugular  ganglion  of 
do. 

Pneumogastric. 
Ganglion  of  root. 


Spinal  accessory. 


Hypoglossal. 


Supr.  cervical  gan- 
glion. 
1st  cervical  n. 

Br.  to  ganglion  of 
trunk. 

2nd  cervical  n. 


DIAGRAM  OF  THE  COMMUNICATIONS  OF  THE  FACIAL,  GLOSSO-PHARYNGEAL,  PNEUMO- 
GASTRIC, SPINAL  ACCESSORY,  HYPOGLOSSAL,  SYMPATHETIC,  AND  THE  TWO  UPPEU 
CERVICAL  NERVES. 


1.  Great  petrosal  nerve. 

2.  Lesser  do. 

3.  External       do. 


4.  Nerve  to  stapedins  muscle. 

5.  Spheno-palatine  ganglion. 

6.  Otic  ganglion. 


their  minuteness,  but  because  they  frequently  run  in  canals  in  the 
temporal  bone. 


NERVES  AT  BASE  OF  THE  SKULL.  265 

The  otic  ganglion  sends  a  branch  forwards  to  the  tensor  palati, 
and  one  backwards  to  the  tensor  tympani,  on  the  outer  side  of  the 
Eustachian  tube. 


DISSECTION  OF  THE  NINTH,  TENTH,  AND  ELEVENTH  CEANIAL 
NEEVES  AT  THE  BASE  OP  THE  SKULL. 

In  this  dissection  we  propose  to  examine  the  glosso-pharyngeal, 
pneumogastric,  and  spinal  accessory  nerves  in  the  jugular  fossa,  and 
the  ganglia  and  nerves  belonging  to  them  in  this  part  of  their 
course.  These  are  difficult  to  trace,  and  cannot  be  followed  unless 
the  nerves  have  been  previously  hardened  by  spirit,  and  the  bones 
softened  in  acid.  The  next  thing  to  be  done  is  to  remove  the  outer 
wall  of  the  jugular  fossa. 

GLOSSO-PHA-  This  nerve  emerges  from  the  cranium  through  a 

EYNGEAL  NEEVE.  separate  tube  of  dura  mater,  in  front  of  that  for 
the  tenth  and  eleventh  cranial  nerves.  Looking  at  it  from  the 
interior  of  the  skull,  we  notice  that  it  is  situated  in  front,  and 
rather  to  the  inner  side  of  the  jugular  fossa,  where  it  lies  in  a 
groove. 

In  its  passage  through  the  foramen,  the  nerve  presents  two 
enlargements,  termed  the  jugular  and  the  petrous  ganglia. 

The  jugular  ganglion  *  is  found  upon  the  nerve  immediately 
after  its  entrance  into  the  canal  of  the  dura  mater,  and  averages 
about  the  ^th  of  an  inch  in  length  and  breadth.  It  is  situated  on 
the  outer  side  of  the  nerve,  and  does  not  implicate  all  its  fibres. 
According  to  our  observation,  this  ganglion  is  not  infrequently 
absent  (fig.  63). 

The  petrous  ganglion 2  is  lodged  in  a  groove  in  the  lower  part  of 
the  jugular  fossa.  It  is  oval,  about  a  quarter  of  an  inch  long,  and 
involves  all  the  filaments  of  the  nerve.  From  it  are  given  off 
branches  of  communication  with  other  nerves  and  the  tympanic 
nerve3  (fig.  63). 

1  Muller,  Medicin.  Zeitung,  Berlin,  1833.    No.  52. 

2  Andersch,  Fragm.  Descript.  Nerv.  Cardiac.     1791. 

3  This   nerve,  though   commonly  called   Jacobson's,  was   fully  described  by 
Andersch. 


266  TYMPANIC    BRANCH    OF    THE    GLOSSO-PHARYNGEAL. 

The  communicating  brandies  which  connect  this  ganglion  with 
the  pneumogastric  are,  one  to  its  auricular  branch,  and  a  second  to- 
the  ganglion  of  the  root.  It  is  also  connected  with  the  sympathetic 
by  a  small  filament  from  the  superior  cervical  ganglion.  Another 
communicating  branch  pierces  the  posterior  belly  of  the  digastricus 
to  join  the  facial  just  external  to  the  stylo-mastoid  foramen. 

The  tympanic  nerve  ( Jacobson's)  ascends,  through  a  minute  canal 
in  the  bony  ridge  which  separates  the  carotid  from  the  jugular 
fossa,  to  the  inner  wall  of  the  tympanum,  grooving  the  surface  of 
the  promontory,  where  it  terminates  in  -six  filaments.  Of  these 
three  are  branches  of  distribution,  and  three  of  communication  with 
other  nerves.  The  branches  of  distribution  are,  one  each  to  the 
fenestra  rotunda  and  the  fenestra  ovalis,  which  pass  backwards, 
and  one  to  the  Eustachian  tube,  which  is  directed  forwards.  The 
branches  of  communication  are  four  small  filaments ;  one  or  two  tra- 
verse a  bony  canal  in  the  anterior  wall  of  the  tympanum,  and  arch- 
ing forwards,  join  the  plexus  on  the  outer  side  of  the  carotid  artery ; 
another,  the  small  deep  petrosal  nerve,  runs  in  a  canal  in  the  pro- 
cessus  cochleariformis,  passes  through  the  foramen  lacerum  medium 
to  join  the  carotid  plexus ;  a  third  ascends  in  front  of  the  fenestra 
ovalis,  and,  passing  forwards,  joins  the  great  petrosal  nerve  in  the 
hiatus  Fallopii ;  the  fourth  leaves  the  front  of  the  tympanum,  under 
the  name  of  the  small  superficial  petrosal  nerve,  through  a  canal, 
where  it  is  joined  by  a  filament  from  the  geniculate  ganglion  of 
the  facial  nerve;  then  passing  beneath  the  canal  for  the  tensor 
tympani,  it  emerges  through  a  foramen  on  the  anterior  surface  of 
the  pars  petrosa,  external  to  the  hiatus  Fallopii ;  it  proceeds  along 
the  anterior  surface  of  pars  petrosa,  and  emerges  from  the  skull 
between  the  great  wing  of  the  sphenoid  and  the  petrous  bones  to 
join  the  otic  ganglion.  Thus  the  tympanic  branch  is  distributed 
to  the  mucous  membrane  of  the  tympanum  and  the  Eustachian 
tube,  and  communicates  with  the  spheno-palatine  ganglion  through 
the  great  petrosal  nerve,  and  with  the  otic  ganglion  through  the 
lesser  petrosal  (fig.  62). 

PNEUMOGASTRIC          This  nerve  leaves  the  cranium  with  the  nervus 
NEBVE.  accessorius  through  a  common  canal  in  the  dura 

mater,  behind  that  for  the  glosso-pharyngeal.     At  its  entrance  into 


PNEUMOGASTRIC    NERVE.  267 

the  canal,  it  is  composed  of  a  number  of  separate  filaments,  which 
are  soon  collected  into  a  single  trunk.  In  the  jugular  foramen,  the 
nerve  presents  a  ganglionic  enlargement,  called  the  ganglion  of  the 
root  •  and  after  the  nerve  has  emerged  from  the  jugular  foramen,  it 
presents  a  second  ganglion — the  ganglion  of  the  trunk  of  the  nerve 
— where  it  is  joined  by  the  accessory  portion  of  the  spinal  accessory 
nerve.1  The  ganglion  of  the  root  is  about  ^th  of  an  inch  in  length. 
It  is  connected  by  filaments  with  the  sympathetic  through  the 
superior  cervical  ganglion,  with  the  petrous  ganglion  of  the  glosso- 
pharyngeal,  with  the  auricular  branch  of  the  facial,  and  with  the 
spinal  accessory  by  one  or  two  branches.  It  gives  off  the  auricular 
branch*  which  is  distributed  to  the  pinna  of  the  ear.  This  branch, 
shortly  after  its  origin,  is  joined  by  a  branch  from  the  petrous  gan- 
glion of  the  glosso-pharyngeal,  and,  passing  outwards  behind  the 
internal  jugular  vein,  it  enters  a  minute  foramen  in  the  jugular 
fossa  near  the  styloid  process.  It  then  proceeds  through  a  canal  in 
the  bone,  crosses  the  aquaeductus  Fallopii,  where  it  communicates 
with  the  facial  nerve,  and  passes  to  the  outside  of  the  skull  through 
the  fissure  between  the  mastoid  process  and  the  meatus  auditorius 
externus.  It  here  divides  into  two  branches,  one  being  distributed 
to  the  skin  of  the  auricle,  and  communicating  with  the  great  auri- 
cular nerve;  the  other  communicating  with  the  posterior  auricular 
branch  of  the  facial  over  the  mastoid  process.  This  ganglion  also 
sends  backwards  a  meningeal  branch,  which  passes  through  the 
jugular  foramen  to  be  distributed  to  the  dura  mater  of  the  posterior 
fossa  (fig.  63). 

The  ganglion  of  the  trunk  has  communications  with  the  hypo- 
glossal  nerve,  with  the  loop  formed  between  the  first  and  second 
cervical  nerves,  and  with  the  superior  cervical  ganglion  of  the  sym- 
pathetic. It  gives  off,  as  branches  of  distribution,  the  pharyngeal 
and  superior  laryngeal  nerves.  This  has  been  previously  described 
(P-  147). 

FACIAL  NERVE  The  facial  nerve  is  contained  within  the  meatus 

IN  THE  auditorius   internus,  together  with  the    auditory 

TEMPORAL  BONK.       nerve.      At  the   bottom  of  the  meatus   the    two 

1  Arnold,  Der  Kopftlieil  dcs  Veget.  Nerven  Systems.    Heidelberg,  1831. 
8  Arnold's  nerve. 


268 


FACIAL   NERVE    IN   THE    TEMPORAL    BONE. 


nerves  are  connected  by  one  or  more  filaments.  The  facial  nerve 
then  enters  the  aquaeductus  Fallopii.  This  is  a  tortuous  canal 
in  the  substance  of  the  temporal  bone,  and  terminates  at  the  stylo- 
mastoid  foramen.  The  nerve  proceeds  from  the  meatus  audi- 
torius  internus  for  a  short  distance  outwards  towards  the  hiatus 
Fallopii,  where  it  presents  a  gangl ionic  enlargement — the  intume- 
scentia  gangliformis,  or  geniculate  ganglion — where  it  is  joined  by 
several  nerves ;  it  then  makes  a  sudden  bend  backwards  along  the 
inner  wall  of  the  tympanum  above  the  fenestra  ovalis,  and  lastly, 

FIG.  64. 


1 .  The  chorda  tympani. 

2.  The  geniculate  ganglion 

of  the  facial  nerve. 

3.  The  great  petrosal  nerve. 
-4.  The  lesser  petrosal  nerve 

lying  over  the  tensor 
tympani. 


5.  The  external  petrosal 
nerve  communicating 
•with  the  sympathetic 
plexus  on  the  arteria 
meningea  media  (6). 

7.  The  Gasserian  ganglion. 


THE    GENICULATE     GANGLION    OF    THE     FACIAL    NEKVE,    AND    ITS    CONNECTIONS    WITH    THE 

OTHER  NEHVES.     (From  Bidder.) 

curving  downwards  along  the   back  of  the  tympanum,  it  leaves 
the  skull  through  the  stylo-mastoid  foramen. 

Its  branches  of  communication  in  the  temporal  bone  are  :  — 

Those  in  the  meatus  auditorius  internus — 

a.  With  the  auditory  nerve. 

Those  in  the  aquaeductus  Fallopii — 

b.  With  Meckel's  ganglion  through  the  large  petrosal  nerve. 

c.  With  the  otic  ganglion  through  the  small  superficial   petrosal 
nerve. 

d.  With    the    sympathetic    around    the   middle   meningeal   artery 
through  the  external  superficial  petrosal  nerve. 


FACIAL   NERVE    IN    THE    TEMPORAL    BONE.  2691 

Its  branches  of  distribution  are: — 

e.  The  tympanic  branch. 
f.  The  chorda  tympani. 

a.  The  communicating  brandies  with  the  auditory  are  by  several 
filaments,  in  the  meatus  auditorius  internus. 

5.  The  large  petrosal  nerve  joins  the  carotid  branch  from  the 
sympathetic  to  form  the  Vidian  nerve,  which  joins  the  spheno- 
palatine  ganglion  (fig.  64,  3). 

c.  The  small  superficial  petrosal  nerve  passes  along  the  anterior 
surface  of  the  pars  petrosa  to  join  the  otic  ganglion  below  the  fora- 
men ovale  (fig.  64,  4). 

d.  The  external  superficial  petrosal  nerve  passes  from  the  gen- 
iculate  ganglion  to  the  sympathetic  plexus   around   the  middle 
meningeal  artery  (fig.  64,  5). 

e.  The  tympanic  branch  passes  through  a  foramen  in  the  base 
of  the  posterior  pyramid  to  supply  the  stapedius  and  the  laxator 
tympani *  (fig.  63,  4). 

/.  The  chorda  tympani  is  given  off  from  the  facial  nerve  before 
its  exit  from  the  stylo-mastoid  foramen.2  It  ascends  a  short 
distance  in  a  bony  canal  at  the  back  of  the  tympanum,  and  enters 
that  cavity  through  a  small  foramen — foramen  chordae  posterius — 
below  and  external  to  the  pyramid,  close  to  the  membrana  tympani. 
It  runs  forwards,  ensheathed  in  mucous  membrane,  through  the 
tympanum,  between  the  handle  of  the  malleus  and  the  long  pro- 
cess of  the  incus,  to  the  anterior  part  of  that  cavity.  It  emerges 
through  a  small  aperture — foramen  chordae  anterius — then  traverses 
a  special  bony  canal — canal  of  Huguier — and  makes  its  exit  close  to 
the  fissura  Glaseri.  It  passes  downwards  and  forwards  between 
the  two  pterygoid  muscles,  behind  the  arteria  meningea  media, 
the  auriculo-temporal  and  inferior  dental  nerves,  to  join,  at  an  acute 
angle,  the  lower  border  of  the  gustatory  nerve.  It  then  proceeds 
in  part  to  the  submaxillary  ganglion,  and  in  part  to  the  lingualis 
muscle. 

1  This  is  often  not  muscular,  but  ligamentous  in  structure. 

2  In  the  foetus,  this  nerve  is  given  off  outside  the  foramen,  but  subsequently 
the  bone  grows  downwards  so  as  to  enclose  more  of  the  facial  nerve,  and  with  it 
the  chorda  tympani. 


270          INTERNAL    CAROTID    ARTERY    THROUGH    BASE    OF   SKULL. 

External  to  the  stylo-mastoid  foramen,  the  facial  nerve  com- 
municates with  the  pneumogastric,  the  glosso-pharyngeal,  the 
great  auricular,  the  auriculo-temporal  nerves,  and  with  the  carotid 
plexus  ;  and  on  the  face,  with  the  numerous  branches  of  the  three 
divisions  of  the  fifth  nerve.  Its  branches  of  distribution,  close  to 
the  stylo-mastoid  foramen,  are  the  posterior  auricular,  digastric  and 
stylo-hyoid  branches ;  and  on  the  face,  branches  to  all  the  facial 
muscles  and  the  platysma  myoides. 

COURSE  OF  THE  ^e  cervical  portion  of  the  internal  carotid  has 

INTERNAL  CAROTID  been  already  described  (p.  144).  Its  subsequent 
THROUGH  BASE  OF  course  may  be  divided  into  the  petrous,  cavernous, 
SKULL.  an(j  cerebrai  portions. 

In  the  petrous  portion,  the  artery  takes  a  very  tortuous  course  : 
at  first  it  ascends  for  a  short  distance  ;  it  then  curves  forwards  and 
inwards ;  and  lastly,  it  again  ascends  to  reach  the  side  of  the  body 
of  the  sphenoid.  It  is  situated  in  front  of  the  tympanum,  from 
which  it  is  separated  by  a  thin  lamella  of  bone,  which  is  frequently 
absorbed  in  advanced  age.  It  gives  off  a  tympanic  branch  to  the 
tympanum  and  membrana  tympani. 

In  the  cavernous  portion,  the  artery  again  makes  a  series  of 
curves  :  at  first  it  ascends  forwards  on  the  side  of  the  body  of  the 
sphenoid,  and  then  curves  upwards  on  the  inner  side  of  the  anterior 
clinoid  process.  The  artery  in  this  part  of  its  course  lies  in  the 
inner  wall  of  the  cavernous  sinus,  having  the  sixth  nerve  below 
and  to  its  outer  side.  From  this  portion  are  given  off  arterice  re- 
ceptaculi  to  supply  the  pituitary  body,  Gasserian  ganglion,  and 
neighbouring  structures ;  the  anterior  meningeal  to  supply  the 
dura  mater;  and  the  ophthalmic  artery  already  described  (p.  57). 

In  the  cerebral  pm'tion,  it  pierces  the  dura  mater  on  the  inner 
side  of  the  anterior  clinoid  process,  and  is  surrounded  by  a  sheath 
of  the  arachnoid  membrane.  It  gives  off  the  anterior  cerebral,  the 
middle  cerebral,  the  anterior  choroid,  and  the  posterior  communi- 
cating arteries. 

The  internal  carotid  is  accompanied  in  the  carotid  canal  by  the 
cranial  branch  of  the  superior  cervical  ganglion  of  the  sympathetic, 
described  p.  151.  Its  position  on  the  inner  wall  of  the  cavernous 
sinus,  and  the  nervous  plexuses  upon  it,  are  described  at  p.  23. 


DISSECTION   OF   THE   NOSE.  271 

At  this  stage  of  the  dissection  we  may  conveniently  trace  the 
anterior  divisions  of  the  two  upper  cervical  nerves. 

SUBOCCIPITAL  The  anterior  division  of  the  first  cervical  or  sub- 

NEBVE.  occipital  nerve  descends  in  front  of  the  transverse 

process  of  the  atlas  to  form  a  loop  with  the  ascending  branch  of 
the  second  cervical  nerve.  It  lies  beneath  the  vertebral  artery,  on 
the  inner  side  of  the  rectus  capitis  lateralis,  to  which  it  gives  a 
branch  ;  as  also,  one  to  the  occipito-atloid  joint,  one  to  the  rectus 
capitis  anticus  minor,  and  one  to  the  sympathetic  around  the 
vertebral  artery.  From  its  loop  of  communication  with  the  second 
nerve  it  gives  filaments  of  communication  to  the  superior  cervical 
ganglion,  to  the  hypoglossal  and  pneumogastric  nerves ;  and 
muscular  branches  to  the  longus  colli  and  rectus  capitis  anticus 
major. 

SECOND  CEBVI-  The  anterior  division  of  this  nerve  emerges  be- 

CAL  NEBVE.  tween  the  arches  of  the  atlas  and  axis,  and  passes 

between  the  vertebral  artery  and  the  intertransverse  muscle,  in 
front  of  which  it  subdivides  into  an  ascending  branch  which  joins 
the  first  cervical  nerve,  and  into  a  descending  which  joins  the  third 
cervical  nerve. 

DISSECTION   OF   THE   NOSE. 

Presuming  that  the  dissector  is  familiar  with  the  bones  com- 
posing the  skeleton  of  the  nose,  we  shall  now  describe :  1 .  The 
nasal  cartilages ;  2.  The  general  figure  and  arrangement  of  the 
nasal  cavities ;  3.  The  membrane  which  lines  them  ;  and,  4.  The 
distribution  of  the  olfactory  nerves. 

CARTILAGES  OF  THE  The  framework  of  the  external  nose  is  formed 
NOSE.  by  five  cartilages;  on  each  side  by  two  lateral 

cartilages ;  and  by  one  in  the  centre,  which  completes  the  septum 
between  the  nasal  fossae. 

The  lateral  cartilages  are  termed,  respectively,  upper  and  lower, 
which  are  covered  externally  by  integument,  and  are  lined  internally 
by  mucous  membrane.  The  upper,  triangular  in  shape,  is  connected 
superiorly  to  the  margin  of  the  nasal  and  superior  maxilla  r  y  bones ; 
anteriorly,  which  is  its  thickest  part,  to  the  cartilage  of  the  septum ; 


272 


CARTILAGES    OF   THE    NOSE. 


and,  inferiorly,  to  the  lower  cartilage  by  means  of  a  tough  fibrous 
membrane.  The  lower  is  elongated,  and  curved  upon  itself  in  such 
a  way  as  to  form  not  only  half  the  apex,  but  the  outer  and  inner 
boundaries  of  the  external  opening  of  the  nostrils.  Superiorly,  it 


FIG.  65. 


SESAMOID 
CARTILAGES 


CARTILAGE   OF.  SEPTUM 
UPPER.LATERAL  CARTILAGE 

LOWER  LATERAL  CARTILAGE. 


CARTILAGES    OF    THE    NOSE. 


is  connected  by  fibrous  membrane  to  the  upper  cartilage ;  internally, 
it  is  in  contact  with  its  fellow  of  the  opposite  side,  forming  the 
upper  part  of  the  columna  nasi ;  posteriorly,  it  is  attached  by 
fibrous  tissue  to  the  superior  maxillary  bone  ;  in  this  tissue  are 
usually  found  two  or  three  nodules  of  cartilage,  called  cartilagines 
sesamoidece ;  below,  it  is  firmly  connected  to  dense  connective 
tissue.  By  their  elasticity  these  several  cartilages  keep  the  nostrils 
continually  open,  and  restore  them  to  their  ordinary  size  whenever 
they  have  been  expanded  by  muscular  action. 

The  cartilage  of  the  septum  is  placed  perpendicularly  in  the 
middle  line  ;  it  may  lean  a  little,  however,  to  one  side  or  the  other, 
and  in  some  instances  it  is  perforated,  so  that  the  two  nasal  cavities 
communicate  with  each  other.  The  cartilage  is  smooth  and  flat, 
and  its  outline  is  nearly  triangular.  The  posterior  border  is  re- 
ceived into  a  groove  in  the  perpendicular  plate  of  the  ethmoid ;  the 
anterior  border  is  much  thicker  than  the  rest  of  the  septum,  and  is 
connected,  superiorly,  with  the  nasal  bones,  and  on  either  side  with 
the  lateral  cartilages.  The  inferior  border  is  attached  to  the  vomer 
and  the  median  ridge  at  the  junction  of  the  palatine  processes  of  the 
superior  maxillse. 


THE   NASAL   FOSSAE.  273 

The  nose  receives  its  blood-supply  from  the  lateralis  nasi,  the 
artery  of  the  septum,  the  facial,  the  nasal  branch  of  the  ophthalmic, 
and  the  infra-orbital  arteries.  The  veins  are  returned  to  the  facial 
and  ophthalmic  veins.  The  nerves  are  derived  from  the  nasal 
branch  of  the  ophthalmic,  the  infra-orbital,  and  infra-trochlear 
nerves.  Its  muscles  are  supplied  by  branches  from  the  facial  nerve. 
The  muscles  moving  the  nasal  cartilages  have  been  described 
with  the  dissection  of  the  face  (p.  34). 

INTERIOR  OP  A  vertical  section  should  be  made  through  the 

THE  NOSE.  right  nasal  cavity,  a  little  on  the  same  side  of  the 

middle  line,1  to  expose  the  partly  bony  and  partly  cartilaginous 
partition  of  the  nasal  cavities  (septum  narium).  Each  nasal  fossa 
is  narrower  above  than  below.  The  greatest  perpendicular  depth 
of  each  fossa  is  about  the  centre ;  from  this  point  the  depth  gradu- 
ally lessens  towards  the  anterior  and  the  posterior  openings  of  the 
nose.  Laterally,  each  fossa  is  very  narrow,  in  consequence  of  the 
'projection  of  the  spongy  bones  towards  the  septum  :  this  narrow- 
ness in  the  transverse  direction  explains  the  rapidity  with  which 
swelling  of  the  lining  membrane  from  a  simple  cold  obstructs  the 
passage  of  air. 

BOUNDARIES  OF  The  nasal  fossae  are  bounded  by  the  following 
NASAL  Fossa:.  bones  : — superiorly,  by  the  nasal,  the  nasal  spine 

of  the  frontal,  the  cribriform  plate  of  the  ethmoid,  the  body  of  the 
sphenoid,  and  the  sphenoidal  turbinated  bones ;  inferiority.,  by  the 
horizontal  plates  of  the  superior  maxillary  and  palate  bones ;  inter- 
nally, is  the  smooth  and  flat  septum  formed  by  the  perpendicular 
plate  of  the  ethmoid,  the  ridge  formed  by  the  two  nasal  bones,  the 
vomer,  the  septal  cartilage,  also  by  the  nasal  spine  of  the  frontal, 
the  rostrum  of  the  sphenoid,  and  the  crest  of  the  superior  maxillary 
and  palate  bones ;  externally,  by  the  nasal  process  and  the  inner 
surface  of  the  superior  maxillary,  the  lachrymal,  the  ethmoid,  the 
palate,  the  inferior  turbinated  bones,  and  the  internal  pterygoid 
plate  of  the  sphenoid. 

MEATUSES  OF  The  outer  wall  of  each  nasal  cavity  is  divided  by 

THE  NOSE.  the  turbinated  bones  into  three  comnartments — 

1  This    has    already   been    done   in    order    to    dissect    the   spheno-palatine 
ganglion. 


274  MEATUSES   OF   THE   NOSE. 

meatuses — of  unequal  size  ;  and  in  these  are  orifices  leading  to  air- 
cells — sinuses — in  the  sphenoid,  ethmoid,  frontal,  and  superior 
maxillary  bones.  Each  of  these  compartments  should  be  separately 
examined. 

a.  The  superior  meat  us  is  the  smallest  of  the  three,  and  does 
not  extend  beyond  the  posterior  half  of  the  wall  of  the  nose.     The 
posterior  ethmoidal  and  sphenoidal  cells  open  into  it.     The  spheno- 
palatine  foramen  is  covered  by  the  mucous  membrane,  and  is  pos- 
terior to  the  meatus. 

b.  The  middle  meatus  is  larger  than  the  superior.     At  its  an- 
terior part  a  long  narrow  passage  (infundibulum),  nearly  hidden  by 
a  fold  of  membrane,  leads  upwards  to  the  frontal  and  the  anterior 
ethmoidal  cells.     About  the  middle  a  small  opening  leads  into  the 
antrum  of  the  superior  maxilla :  this  opening  in  the  dry  bone  is 
large  and  irregular,  but  in  the  recent  state  it  is  reduced  nearly 
to  the  size  of  a  crow-quill  by  mucous  membrane,  so  that  a  very 
little  swelling  of  the  membrane  is  sufficient  to  close  the  orifice 
entirely. 

Notice  that  the  orifices  of  the  frontal  and  ethmoid  cells  are  so 
disposed  that  their  secretion  will  pass  easily  into  the  nose.  But 
this  is  not  the  case  with  the  maxillary  cells,  to  empty  which  the 
head  must  be  inclined  on  one  side.  To  see  all  these  openings  the 
respective  turbinated  bones  must  be  raised. 

c.  The  inferior  meatus  extends  nearly  along  the  whole  length  of 
the  outer  wall  of  the  nose.     By  raising  the  lower  turbinated  bone, 
we  observe,  towards  the  front  of  the  meatus,  the  termination  of  the 
nasal  duct,  through  which  the  tears  pass  down  from  the  lachrymal 
sac  into  the  nose.     This  sac  and  duct  can  now  be  conveniently 
examined. 

LACHRYMAL  SAC  The  lachrymal  sac  and  nasal  duct  constitute  the 
AND  NASAL  DUCT.  passage  through  which  the  tears  are  conveyed  from 
the  canaliculi  into  the  nose  (p.  33).  The  lachrymal  sac  occupies 
the  groove  formed  by  the  lachrymal  bone  and  the  nasal  process  of 
the  superior  maxilla.  The  upper  end  is  round  and  closed;  the 
lower  gradually  contracts  into  the  nasal  duct,  and  opens  into  the 
inferior  meatus.  The  sac  is  composed  of  a  strong  fibrous  and  elastic 
tissue,  which  adheres  very  closely  to  the  bone,  and  is  lined  by 


MUCOUS  MEMBRANE  OF  THE  NOSE.  275 

mucous  membrane,  continuous,  above  with  that  lining  the  canaliculi, 
and  below  with  that  of  the  nasal  duct.  Its  front  surface  is  covered 
by  the  tendo  oculi  and  the  fascia  proceeding  from  it,  and  by  the 
tensor  tarsi  muscle. 

The  nasal  duct  is  from  half  to  three-quarters  of  an  inch  in 
length,  and  is  directed  downwards,  backwards,  and  a  little  out- 
wards. Its  termination  is  rather  dilated,  and  is  guarded  by  a  val- 
vular fold  of  mucous  membrane — valve  of  Hasner  •  consequently, 
when  air  is  blown  into  the  nasal  passages  while  the  nostrils  are 
closed,  the  lachrymal  sac  does  not  become  distended.  The  lachry- 
mal sac  and  the  nasal  duct  are  lined  with  ciliated  epithelium,  and 
the  canaliculi  with  the  squamous  variety. 

Behind  the  inferior  turbinated  bone  is  the  opening  of  the  Eus- 
tachian  tube  (p.  236).  Into  this,  as  well  as  into  the  nasal  duct,  we 
ought  to  practise  the  introduction  of  a  probe.  The  chief  difficulty 
is  to  prevent  the  probe  from  slipping  into  the  cul-de-sac  between 
the  tube  and  the  back  of  the  pharynx. 

Mucous  OB  This  membrane  lines  the  cavities  of  the  nose  and 

SCHNEIDERIAN  the  air-cells  communicating  with  it,  and  adheres 

MEMBRANE.'  very  firmly  to  the  periosteum.     Its  continuity  may 

be  traced  into  the  pharynx,  into  the  orbits  through  the  nasal  ducts 
and  canaliculi,  into  the  various  air  sinuses—  viz.,  the  frontal,  eth- 
moidal>  sphenoidal  sinuses,  and  the  antra  of  Highmore,  and  into 
the  tympana  and  mastoid  cells  through  the  Eustachian  tubes.  At 
the  lower  border  of  the  turbinated  bones  it  is  disposed  in  thick  and 
loose  folds.  The  membrane  varies  in  thickness  and  vascularity  in 
different  parts  of  the  nasal  cavities.  Upon  the  lower  half  of  the 
septum  and  the  inferior  turbinated  bones  it  is  much  thicker  than 
elsewhere,  owing  to  a  fine  plexus  of  arteries  and  veins  in  the  sub- 
mucous  tissue.  In  the  sinuses  the  mucous  membrane  is  thinner, 
less  vascular,  and  closely  adherent  to  the  periosteum.2 

1  Schneider,  De  Catarrhis.    Wittenberg,  1660. 

2  In  the  mucous  membrane  covering  the  lower  part  of  the  septum,  in  front,  may 
be  observed  a  small  orifice  which  leads  into  a  narrow  blind  channel,  a  few  millimetres 
in  length.     This  canal  has  numerous  glands  opening  into  it,  and  is  the  represen- 
tative of  a  much  larger  tubular  organ  (organ  of  Jacobson)  in  some  quadrupeds,  in 
whom  it  is  surrounded  by  a  curved  plate  of  cartilage  (cartilage  of  Jacobson).    In 

T  2 


276  MUCOUS  MEMBRANE  OF  THE  NOSE. 

The  great  vascularity  of  the  mucous  membrane  raises  the  tem- 
perature of  the  inspired  air,  and  pours  out  a  copious  secretion  which 
prevents  the  membrane  from  becoming  too  dry. 

The  mucous  membrane  of  the  nasal  cavities  is  not  lined  through- 
out by  the  same  kind  of  epithelium.  Near  the  nostrils  the  mucous 
membrane  is  furnished  with  papillae,  with  a  squamous  epithelium 
like  the  skin,  and  a  few  small  hairs  (vibrissce).  In  the  lower  part 
of  the  nose — namely,  along  the  respiratory  tract  and  in  the  sinuses 
— the  epithelium  is  columnar  and  ciliated  ;  but  in  the  true  olfactory 
region — that  is,  upon  the  superior  and  middle  turbinated  bones 
and  the  upper  half  of  the  septum — the  epithelium  is  columnar,  but 
not  ciliated.  In  this  region  the  mucous  membrane  is  extremely 
vascular,  thick,  and  studded  with  branched  mucous  glands.  The 
columnar  epithelial  cells  taper  off  at  their  deep  ends  into  fine  pro- 
cesses. Lying  between  these  processes  are  fusiform  cells,  with 
central  well-defined  nuclei,  to  which  the  name  of  olfactory  cells  J 
has  been  given  ;  and  it  is  probable  that  the  attenuated  processes 
which  pass  inwards  from  these  cells  are  in  direct  connection  with 
the  terminal  fibrils  of  the  olfactory  nerves. 

The  arteries  of  the  nasal  cavities  are  derived  from  the  anterior 
and  posterior  ethmoidal  branches  of  the  ophthalmic,  which  supply 
the  roof  of  the  nose,  the  anterior  and  posterior  ethmoidal  cells,  and 
the  frontal  sinuses  ;  from  the  nasal  artery  of  the  internal  maxillary, 
which  supplies  the  septum,  the  meatuses,  and  the  turbinated  bones  ; 
from  the  posterior  dental  branch  of  the  internal  maxillary  which 
supplies  the  antrum.  The  external  nose  is  supplied  by  the  nasal 
branch  of  the  ophthalmic  (p.  59),  the  arteria  lateralis  nasi,  the 
angular,  and  the  artery  of  the  septum.  . 

The  veins  of  the  nose  correspond  with  the  arteries,  and,  like 
them,  form  close  plexuses  beneath  the  mucous  membrane.  They 
communicate  with  the  veins  within  the  cranium,  through  the  fora- 
mina in  the  cribriform  plate  of  the  ethmoid  bone  ;  also  through  the 
ophthalmic  vein  and  the  cavernous  sinus.  These  communications 

man  this  cartilage  is  very  narrow,  and  is  situated  below  the  rudimentary  organ. 
For  further  information,  see  Klein,  Quart.  Journ.  of  Micros.  Science,  1881  and 
1882. 

1  Max  Schultze,  Med.  Centralblatt,  1864. 


OLFACTORY   NERVES.  277 

explain  the  relief  frequently  afforded  by  haemorrhage  from  the  nose 
in  cases  of  cerebral  congestion. 

The  mucous  membrane  of  the  nose  is  supplied  with  sensory 
nerves  by  the  fifth  pair.  Thus,  its  roof  is  supplied  by  filaments 
from  the  external  division  of  the  nasal  branch  of  the  ophthalmic, 
and  from  the  Vidian ;  its  outer  wall,  by  filaments  from  the  superior 
nasal  branches  of  the  spheno-palatine  ganglion,  from  the  nasal, 
from  the  inner  branch  of  the  anterior  dental,  and  from  the  inferior 
nasal  branches  of  the  large  palatine  nerve ;  its  septum,  by  the 
septal  branch  of  the  nasal  nerve,  by  the  nasal  branches  of  the 
spheno-palatine  ganglion,  by  the  naso-palatine,  and  by  the  A7idian  ; 
its  floor,  by  the  naso-palatine,  and  the  inferior  nasal  branches  of 
the  large  palatine  nerve. 

OLFACTORY  The  olfactory  nerves,  proceeding  from  each  olfac- 

NEKVES.  tory  bulb,  in  number  about  twenty  on  .each  side, 

pass  through  the  foramina  in  the  cribriform  plate  of  the  ethmoid 
bone.  In  its  passage  each  nerve  is  invested  with  a  coat  derived 
from  the  dura  mater.  They  are  arranged  into  an  inner,  a  middle, 
and  an  outer  set.  The  septal,  which  are  -the  largest,  traverse  the 
grooves  in  the  upper  third  of  the  septum.  The  middle  ramify 
on  the  roof  of  the  nose.  The  outer  pass  through  grooves,  and  are 
divided  into  an  anterior  and  a  posterior  group :  the  anterior  being 
distributed  over  the  superior  turbinated  bone,  the  posterior  over 
the  os  planum  of  the  ethmoid  and  the  middle  turbinated  bone. 

The  nerves  descend  obliquely  between  the  mucous  membrane 
and  the  periosteum,  and  break  up  into  filaments,  which  communi- 
cate freely  with  one  another,  and  form  minute  plexuses  with  small 
elongated  intervals.  Microscopically,  the  filaments  differ  from  the 
other  cerebral  nerves,  in  containing  no  white  substance  of  Schwann, 
and  in  their  axis-cylinders  being  provided  with  a  very  distinct 
nucleated  sheath  with  fewer  nuclei  and  at  longer  intervals. 


278  MUSCLES    OF    THE    BACK. 


DISSECTION   OF   THE   MUSCLES   OF   THE   BACK. 

DISSECTION  TO  Those  muscles  of  the  back — namely,  the  tra- 

EXPOSE  THE  THIED  pezius,  latissimus  dorsi,  levator  anguli  scapulas, 
LAYER  OF  an(J  rhomboidei — which  are  concerned  in  the 

movements  of  the  upper  extremity,  will  be  ex- 
amined in  the  dissection  of  the  arm.  These  must  be  reflected 
near  to  their  insertions,  together  with  the  cutaneous  vessels  and 
nerves.  We  now  proceed  to  examine  the  three  muscles  forming 
the  third  layer  of  muscles,  named,  from  their  appearance,  serrati 
postici,  superior  and  inferior,  and  the  splenius.  The  nerves  and 
arteries  will  be  described  after  the  dissection  of  the  suboccipital 
triangle. 

SERBATUS  Pos-  This  muscle  is  situated  beneath  the  rhomboidei. 

TICUS  SUPERIOR.  It  is  a  thin  flat  muscle,  and  arises  from  the  lower 
part  of  the  ligamentum  nuchas,1  from  the  spinous  processes  of  the 
last  cervical,  and  two  or  three  upper  dorsal  vertebra,  by  a  sheet- 
like  aponeurosis  which  makes  up  nearly  half  the  muscle ;  the  fibres 
run  obliquely  downwards  and  outwards,  and  are  inserted  by  four 
fleshy  slips  into  the  second,  third,  fourth,  and  fifth  ribs  beyond 
their  angles.  Its  action  is  to  raise  these  ribs,  and  therefore  to 
assist  in  inspiration. 

SERRATTJS  Pos-  This  muscle  is  situated  in  the  upper  lumbar 

TICUS  INFERIOR.  region,  beneath  the  latissimus  dorsi.  It  arises, 
by  means  of  the  lumbar  aponeurosis,  from  the  spinous  processes 
of  the  two  last  dorsal  and  two  upper  lumbar  vertebras  and  their 
supra-spinous  ligament.  It  ascends  obliquely  outwards,  and  is 
inserted  by  four  fleshy  slips  into  the  four  lower  ribs,  external  to 
their  angles.  Its  action  is  to  pull  down  these  ribs,  and  therefore 
to  assist  in  expiration.  The  posterior  serrati  muscles  are  supplied, 

1  The  ligamentum  nuchse  is  a  rudiment  of  the  great  elastic  ligament  of  quadru- 
peds (termed  the  pack-wax)  which  supports  the  weight  of  the  head..  It  proceeds 
from  the  spine  of  the  occiput  to  the  spines  of  all  the  cervical  vertebrae  except  the 
atlas  ;  otherwise  it  would  interfere  with  the  free  rotation  of  the  head. 


VERTEBRAL   APONEUROSIS.  279 

respectively,  by  the  external  branches  of  the  posterior  divisions  of 
the  cervical  and  dorsal  nerves. 

VERTEBRAL  The  thin  aponeurosis  which,   in  the  posterior 

APONEUROSIS.  aspect  of  the  thoracic  region,  separates  the  muscles 

of  the  upper  extremity  from  those  of  the  back,  is  called  the  vertebral 
aponeurosis.  Superiorly,  it  is  continued  beneath  the  splenius,  and  is 
continuous  with  the  deep  cervical  fascia ;  inferiorly,  it  binds  down 
the  muscles  contained  in  the  vertebral  groove,  and  is  attached  to  the 
upper  border  of  the  serratus  posticus  inferior,  and  the  tendon  of  the 
latissimus  dorsi ;  internally,  it  is  attached  to  the  spinous  processes 
of  the  dorsal  vertebras,  and  externally  to  the  angles  of  the  ribs. 

This    aponeurosis   consists    of  three  layers,  of 
LUMBAR  FASCIA.          ,  .  .         .      , ,  ,  , 

which  only  the  posterior  layer  can  now  be  seen  ; 

the  other  two  being  demonstrated  in  the  dissection  of  the  abdo- 

FIG.  60. 


ERECTOR     SP. 


TRANSVERSE  SECTION  THROUGH  THE  ABDOMEN  TO  SHOW  THE  ATTACHMENT  OF  THK 
THREE  LAYERS  OF  THE  LUMBAR  FASCIA  TO  THE  TRANSVERSE  AND  SPINOUS 
PROCESSES  OF  THE  LUMBAR  VERTEBRAE. 

minal  muscles.  The  posterior  or  superficial  layer  is  attached  to 
the  crest  of  the  ilium,  to  the  spinous  processes  of  all  the  lower 
dorsal ,  lumbar,  and  sacral  vertebras ;  it  forms  a  sheath  for  the 
erector  spinae,  and  serves  for  the  attachment  of  the  latissimus 
dorsi,  the  serratus  posticus  inferior,  and  the  internal  oblique. 


280 


MUSCLES   OF   THE   BACK. 


PIG.  67. 


THE    SUPERFICIAL    MUSCLES    OF    THE    BACK. 


MUSCLES   OF   THE   BACK.  281 

The  serratus  posticus  superior  must  now  be  reflected  from  its 
origin,  and  turned  outwards  to  expose  the  following  muscle. 

This  muscle,  so  called  from  its  resemblance  to 
SPLENIDS.  „  ,  „    , 

a  strap,  arises  from  the  spinous  processes  of  the 

five  or  six  upper  dorsal  and  the  last  cervical  vertebrae,  from  the 
supra-spinous  ligament,  and  from  the  lower  half  of  the  ligamentum 
nuchae.  The  fleshy  fibres  pass  upwards  and  outwards  and  divide 
into  two  portions,  named,  according  to  their  respective  insertions, 
splenius  capitis  and  splenius  colli. 

a.  The  splenius  capitis,  the  inner  of  the  two  portions,  is  in- 
serted into  the   mastoid  process,  and  into  the  outer  part  of  the 
superior  curved  line  of  the  occipital  bone,  beneath  the  sterno- 
mastoid. 

b.  The  splenius  colli,  the  outer  of  the  two  portions,  is  inserted 
by  tendinous  slips  into  the  posterior  tubercles  of  the  transverse 
processes  of  the  upper  three  cervical  vertebrae.     The  splenius  is 
supplied  by  the  external  branches  of  the  posterior  divisions  of  the 
cervical  nerves. 

The  action  of  the  splenius,  taken  as  a  whole,  is  to  draw  the 
head  and  the  upper  cervical  vertebras  towards  its  own  side :  so 
far,  it  co-operates  with  the  opposite  sterno-mastoid  muscle.  When 
the  splenii  of  opposite  sides  contract,  they  extend  the  cervical 
portion  of  the  spine,  and  keep  the  head  erect.  The  permanent 
contraction  of  a  single  splenius  may  occasion  wry-neck.  It  is 
necessary  to  be  aware  of  this,  otherwise  one  might  suppose  the 
opposite  sterno-mastoid  to  be  affected,  considering  that  the  ap- 
pearance of  the  distortion  is  alike  in  either  case. 

DISSECTION  TO  To  lay  bare  the  fourth  layer  of  muscles,  the 

EXPOSE  THE  splenius  and  serratus  posticus  inferior  are  to  be 

FOURTH  LATER.  detached  from  their  origins.  After  reflecting  the 
vertebral  aponeurosis  and  the  lumbar  fascia  from  its  internal 
attachment,  the  erector  spinas  and  its  prolongations  are  exposed. 

The  mass  of  muscle  which  occupies  the  vertebral 
groove  on  each  side  of  the  spine,  is,  collectively, 
called  erector  spince,  since  it  counteracts  the  tendency  of  the  trunk 
to  fall  forwards.  It  is  pointed  at  its  lower  tendinous  extremity 
where  it  arises  from  the  sacral  region  ;  in  the  lumbar  region 
it  is  broad,  thick  and  muscular;  in  the  lower  dorsal  region 


282 


ERECTOR    SPIN.E. 


\ 


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O 

O 


o 
ft 


3 


PS 

8 

o 

w 

PS 

w 


ARRANGEMENT  OF  THE  ERECTOR 
SPIN.E  AND  IITS  PROLONGATIONS 
INTO  THE  POSTERIOR  THORACIC 
AND  CERVICAL  REGIONS. 


it  divides  into  two  portions,  which 
are  continued  upwards  with  addi- 
tional muscles  into  the  cervical  verte- 
bra and  the  head.  Observe  that  it 
is  thickest  and  strongest  at  that  part 
of  the  spine  where  it  has  the  greatest 
weight  to  support — namely,  in  the 
lumbar  region  ;  and  that  its  thickness 
gradually  decreases  towards  the  top  of 
the  spine. 

It  arises  by  thick  tendinous  fibres 
from  the  spinous  processes  of  the  two 
or  three  lowest  dorsal  and  of  all  the 
lumbar  vertebras,  from  the  spines  of 
the  sacrum,  from  the  supra-spinous 
ligament,  from  the  posterior  fifth  of 
the  inner  lip  of  the  crest  of  the  ilium, 
from  the  lower  and  back  part  of  the 
sacrum,  and  from  the  posterior  sacro- 
iliac  ligament.  From  this  extensive 
origin  the  muscular  fibres  ascend,  at 
first  as  a  single  mass.  Near  the  last 
rib,  this  mass  divides  into  two :  an 
outer,  called  the  ilio-costalis  or  sacro- 
lumbalis ;  an  inner,  the  long-issimus 
dor  si.  These  two  portions  should  be 
followed  up  the  back  ;  and  there  is 
no  difficulty  in  doing  so,  because  the 
division  is  indicated  by  a  longitudinal 
groove,  in  which  we  observe  the  ex- 
ternal cutaneous  branches  of  the  in- 
tercostal vessels  and  nerves. 

ILIO-COSTALIS  OK  Tracing  the  ilio-cos- 
SACRO-LUMBALIS.  ialis  or  sacro-lumbalis 
upwards,  we  find  that  it  terminates 
in  a  series  of  tendons  which  are  in- 
serted into  the  angles  of  the  six  lower 
ribs. 


MUSCLES   OF   THE   BACK.  283 

MUSCULUS  By  turning  outwards  the  ilio-costalis,  we 

ACCESSORIUS.  observe  that  it  is  continued  upwards  under  the 

name  of  musculus  accessorius  ad  ilio-costalem.  This  arises  by  a 
series  of  tendons  from  the  angles  of  the  six  lower  ribs,  internal 
to  the  preceding,  and  is  inserted  by  muscular  slips  into  the  angles  of 
the  six  upper  ribs. 

CERVICALIS  This  is  the  cervical  continuation  of  the  musculus 

ASCENDENS.  accessorius.  It  arises  by  tendinous  slips  from  the 

angles  of  the  four  or  five  upper  ribs,  internal  to  the  musculus 
accessorius,  and  is  inserted  into  the  posterior  tubercles  of  the 
transverse  processes  of  the  fourth,  fifth  and  sixth  cervical  ver- 
tebrae. 

LONGISSIMUS  The  longissimus  dorsi  (the  inner  portion  of  the 

DORSI.  erector  spina3)  terminates  in  tendons  which  are 

inserted,  internally,  into  the  tubercles  *  at  the  root  of  the  transverse 
processes  of  the  lumbar  vertebra3,  into  the  tubercles  of  the  articular 
processes  of  the  same  vertebrae,  into  the  middle  layer  of  the  fascia 
lumborum,  also  into  the  transverse  processes  of  all  the  dorsal 
vertebrae  and,  externally,  into  the  greater  number  of  the  ribs  (vary- 
ing from  eight  to  eleven)  between  their  tubercles  and  angles. 

TRANSVEKSALIS  This  is  the  cervical  continuation  of  the  longissi- 

COLLI.  mus  dorsi.  It  arises  by  long  tendinous  slips  from 

the  tips  of  the  transverse  processes  of  the  five  or  six  upper  dorsal 
vertebrae,  and  is  inserted  into  the  posterior  tubercles  of  the  trans- 
verse processes  of  the  four  or  five  lower  cervical  vertebrae  except 
the  last. 

TKACHELO-  This  muscle,  situated  on  the  inner  side  of  the 

MASTOID.  preceding,  and  external  to  the  complexus,  is  the 

internal  continuation  of  the  longissimus  dorsi  to  the  cranium.  It 
arises  from  the  transverse  processes  of  the  three  or  four  upper  dorsal, 
and  the  articular  processes  of  the  three  or  four  lower  cervical  ver- 
tebrae, and  is  inserted  by  a  flat  tendon  into  the  back  part  of  the 
mastoid  process  beneath  the  splenius.2 

1  Called  anapophyses  by  Professor  Owen. 

2  Those  who  are  familiar  with  the  transcendental  nomenclature  of  the  verte- 
brate skeleton  will  understand  from  the  following  quotation  the  plan  upon  which 
the  muscles  of  the  back  are  arranged : — 

'  The  muscles  of  the  back  are  either  longitudinal  or  oblique  :  that  is,  they  either 
pass  vertically  downwards  from  spinous  process  to  spinous  process,  from  diapo- 


.284  MUSCLES   OF  THE   BACK. 

This  is  a  long  narrow  muscle,  situated  close  to 
SPINALIS  DOKSI.        ,  .  /•  .1       i         i         .    i     '  i  ,  •, 

the  spines  or  the  dorsal  vertebras,  and  apparently 

the  inner  part  of  the  longissimus  dorsi ;  it  is  by  some  considered 
the  innermost  column  of  the  erector  spinas.  It  arises  by  tendinous 
slips  from  the  spinous  processes  of  the  two  lower  dorsal  and  two 
upper  lumbar  vertebrae,  and  is  inserted  by  little  tendons  into  the 
spinous  processes  of  the  six  or  eight  upper  dorsal  vertebras.  Beneath 
it,  is  the  semi-spinalis  dorsi,  which  is  closely  connected  with  the 
spinalis  dorsi. 

This  small,  but  not  constant  muscle  corresponds 
SPINAUS  COLLI.       .       ,  .     ,          .  .  .      , .      ,       .    . 1 

in  the  cervical  region  to  the  spinalis  dorsi  in  the 

dorsal  region.  It  arises  by  tendinous  slips  from  the  spinous 
processes  of  the  two  or  three  lower  cervical  vertebras  (sometimes  also 
from  the  two  upper  dorsal),  and  is  inserted  into  the  spine  of  the 
axis,  and  occasionally  into  the  spinous  processes  of  the  third  and 
fourth  cervical. 

physis  to  diapophysis,  from  rib  to  rib  (pleurapophysis),&c.,  or  they  extend  obliquely 
from  diapophysis  to  spine,  or  from  diapophysis  to  pleurapophysis,  &c. 

'  The  erector  spinse  is  composed  of  two  planes  of  longitudinal  fibres  aggregated 
together,  below,  to  form  one  mass  at  their  poini  of  origin,  from  the  spines  and 
posterior  surface  of  the  sacrum,  from  the  sacro-iliac  ligament,  and  from  the  pos- 
terior third  of  the  iliac  crest.  It  divides  into  two  portions,  the  sacro-lumbalis  and 
the  longissimus  dorsi. 

'  The  former,  arising  from  the  iliac  crest,  or  from  the  pleurapophysis  (rib)  o 
the  first  sacral  vertebra,  is  inserted  by  short  flat  tendons  into  (1)  the  apices  of  the 
stunted  lumbar  ribs,  close  to  the  tendinous  origins  of  the  transversalis  abdominis  ; 

(2)  the  angles  of  the  eight  or  nine  inferior  dorsal  ribs  ;  (3)  it  is  inserted,  through 
the  medium  of  the  musculus  accessorius,  into  the  angles  of  the  remaining  supe- 
rior ribs,  and  into  the  long  and  occasionally  distinct  pleurapophysial  element  of  the 
seventh  cervical  vertebra ;  and  (4)  through  the  medium  of  the  cervicalis  ascendens, 
into  the  pleurapophysial  elements  of  the  third,  fourth,  fifth,  and  sixth  cervical 
vertebrae.     In  other  words,  the  muscular  fibres  extend  from  rib  to  rib,  from  the 
sacrum  to  the  third  cervical  vertebra. 

'  The  longissimus  dorsi,  situated  nearer  the  spine  than  the  sacro-lumbalis,  is 
inserted  (1)  into  the  metapophysial  spine  of  the  lumbar  diapophyses ;  (2)  into  the 
diapophyses  of  all  the  dorsal  vertebrae,  near  the  origin  of  the  levatores  costarum  ; 

(3)  through  the  medium  of  the  transversalis  colli  into  the  diapophyses  of  the  second, 
third,  fourth,  fifth,  and  sixth  cervical  vertebrae  ;  and  (4)  through  the  medium  of  the 
trachelo-mastoid  into  the  mastoid  process,  or  the  only  element  of  a  transverse 
process  possessed  by  the  parietal  vertebra.     In  other  words,  its  fibres  extend  from 
diapophysis  to  diapophysis,  from  the  sacrum,  upwards,  to  the  parietal  vertebra.' — 
Homologies  of  the  Human  Skeleton,  by  H.  Coote,  p.  75. 


MUSCLES    OF   THE    BACK.  285 

The  muscles  of  the  spine  hitherto  examined  are  all  longitudinal 
in  their  direction.  We  now  come  to  a  series  which  run  obliquely 
from  the  transverse  to  the  spinous  processes  of  the  vertebras.  And 
first  of  the  complexus. 

This  powerful  muscle  arises  by  tendinous  slips 
from  the  transverse  processes  of  the  three  or  four 
upper  dorsal  and  the  last  cervical  vertebras,  also  from  the  articular 
processes  of  four  or  five  cervical  vertebrae  and  their  capsular  liga- 
ments. It  is  inserted  between  the  two  curved  lines  of  the  occiput, 
near  the  vertical  crest.  In  the  centre  of  the  muscle  there  is  generally 
a  transverse  tendinous  intersection.  The  muscle  is  perforated  by 
the  posterior  branches  of  the  second  (the  great  occipital),  third, 
and  fourth  cervical  nerves.  It  is  chiefly  supplied  by  the  great 
occipital  nerve.  Its  action  is  to  maintain  the  head  erect. 

BIVENTEB  Is  placed  in  the  inner  side   of  the  preceding 

CERVICIS.  muscle  and  frequently  forms  part  of  it.     It  has  an 

intermediate  tendon,  and  arises  from  the  transverse  processes  of 
two  or  three  upper  dorsal  vertebras,  and  ascends  between  the  liga- 
mentum  nuchas  and  the  complexus,  to  be  inserted  into  the  inner- 
most depression  between  the  two  curved  lines  of  the  occipital  bone. 
Cut  transversely  through  the  middle  of  the  complexus,  and 
reflect  it  to  see  the  arteria  cervicalis  profunda  (p.  123),  and  the 
posterior  branches  of  the  cervical  nerves. 

DISSECTION  TO  Remove  the    complexus,  and  then  turn  aside 

EXPOSE  THE  FIFTH  the  erector  spinas  and  its  prolongations,  when  the 
LAYEK>  fifth  layer  of  muscles  will  be  seen  occupying  the 

interval  between  the  spinous  and  transverse  processes. 

TBANSVEESO-  This  is  the  mass  of  muscle  which  lies  in  the 

SPINALIS.  vertebral  groove  after  the  reflection  of  the  com- 

plexus and  the  erector  spinae.  It  consists  of  a  series  of  fibres 
which  extend  from  the  transverse  and  articular  processes  to  the 
spinous  processes  of  the  dorsal  and  cervical  vertebras,  and  is  for 
convenience  divided  into  the  semispinalis  dorsi  and  semispinalis 
colli. 

a.  The  semispinalis  dorsi  arises  by  long  thin  tendinous  slips 
from  the  transverse  processes  of  the  dorsal  vertebras,  from  the  sixth 
to  the  tenth,  and  is  inserted  into  the  spinous  processes  of  the  four 


286  MUSCLES   OF   THE   BACK. 

upper  dorsal  and  the  two  or  three  lower  cervical  vertebrae.  Its 
nerves  are  derived  from  the  internal  posterior  branches  of  the  dorsal 
nerves. 

6.  The  semispinalis  colli  lies  beneath  the  complexus,  and  arises 
from  the  transverse  processes  of  the  five  or  six  upper  dorsal  ver- 
tebrae, and  the  articular  processes  of  the  four  lower  cervical,  and  is 
inserted  into  the  spinous  processes  of  the  axis  and  the  three  or  four 
succeeding  vertebrae,  that  into  the  axis  being  the  most  fleshy  fasci- 
culus. It  is  supplied  by  the  internal  posterior  branches  of  the 
cervical  nerves. 

Now  reflect  part  of  the  semi-spinalis  dorsi  in  order  to  expose  the 
multifidus  spinae. 

MULTIFIDUS  This  may  be  considered  a  part  of  the  preceding 

SPINAE.  muscle,  since  its  fixed  points  and  the  direction  of 

its  fibres  are  the  same.  It  consists  of  a  series  of  little  muscles 
which  extend  between  the  spinous  and  transverse  processes  of  the 
vertebrae,  from  the  sacrum  to  the  second  cervical  vertebra.  Those  in 
the  lumbar  region  are  the  largest.  In  the  sacral  region  the  fibres 
arise  from  the  back  of  the  sacrum  as  low  down  as  the  fourth  fora- 
men, from  the  deep  surface  of  the  aponeurosis  of  the  erector  spinae, 
from  the  inner  part  of  the  posterior  superior  iliac  spine,  and  from 
the  posterior  sacro-iliac  ligament ;  in  the  lumbar  region,  from  the 
mammillary  processes  on  the  superior  articular  processes ;  in  the 
dorsal  region,  from  the  transverse  processes,  and  in  the  cervical 
region  from  the  articular  processes  of  the  four  lower  cervical  ver- 
tebrae. They  all  ascend  obliquely,  and  each  fasciculus  is  inserted 
into  the  lamina  and  spinous  process  of  the  vertebra  above,  except 
the  atlas.  It  should  be  observed  that  their  fibres  are  not  of 
uniform  length  ;  some  extend  only  from  vertebra  to  vertebra,  while 
others  extend  between  one,  two,  or  even  three  vertebrae.  It  is 
supplied  by  the  internal  posterior  branches  of  the  sacral,  lumbar, 
dorsal,  and  cervical  nerves. 

EOTATORES  Beneath    the   multifidus  spinae,   in  the  dorsal 

SPIN.E.  region  of  the  spine  only,  are  eleven  flat  and  some- 

what square  muscles,  called  rotatores  spince.  They  arise  from  the 
upper  and  back  part  of  the  transverse  processes,  and  are  inserted 
into  the  lower  border  of  the  laminas  of  the  vertebra  above.  These 


MUSCLES   OF   THE   BACK.  287 

muscles  form  but  a  part  of  the  multifidus  spinas,  and  are  supplied 
by  the  internal  posterior  branches  of  the  dorsal  nerves. 

The  action  of  the  preceding  muscles  is,  not  only  to  assist  in 
maintaining  the  trunk  erect,  but  to  incline  and  rotate  the  spine 
to  one  or  the  other  side.  They  are  all  supplied  by  the  posterior 
branches  of  the  spinal  nerves. 

LEVATOBES  These  small  muscles,  twelve  in  number,  on  each 

COSTABUM.  side,  arise  from  the  apices  of  the  transverse  pro- 

cesses of  the  seventh  cervical  and  the  eleven  upper  dorsal  vertebrae, 
and  are  inserted  into  the  rib  below.  The  direction  of  their  fibres 
corresponds  with  that  of  the  outer  layer  of  the  intercostal  muscles, 
and  they  are  supplied  by  the  internal  posterior  branches  of  the  dorsal 
nerves.  They  are  muscles  of  inspiration. 

These  are  formed  by  a  series  of  small  muscular 

SUPEA-SPINALES.  ,.  ,      .  ,  „       , 

slips  lying  over  the  spinous  processes  of  the  cer- 
vical vertebras.  Their  nerves  are  derived  from  the  internal  posterior 
branches  of  the  cervical  nerves. 

These  muscles  extend  between  the  spinous  pro- 
INTEB-SPINALES.  ,,  , ,  ,.  ,  ,  mi 

cesses  or  the  contiguous  vertebrae.  Ihey  are  ar- 
ranged in  pairs,  and  only  exist  in  those  parts  of  the  vertebral 
column  which  are  most  moveable.  In  the  cervical  region,  they  are 
the  most  distinct,  and  pass  between  the  spinous  processes  of  the 
six  lower  cervical  vertebrae.  In  the  dorsal,  they  are  found  between 
the  spinous  processes  of  the  first  and  second,  and  between  those 
of  the  eleventh  and  twelfth  dorsal  vertebras.  They  are  also  found 
more  or  less  distinctly  between  the  spinous  processes  of  the  lumbar 
vertebras.  They  are  supplied  by  the  internal  posterior  branches  of 
the  spinal  nerves. 

INTEB-TBANS-  These  muscles  extend  between  the  transverse 

VEBSALES.  processes  of  the  vertebrae.     In  the  cervical  region 

they  are  seven  in  number,  and  are  most  marked,  being  arranged  in 
pairs,  and  extend  between  the  anterior  and  posterior  tubercles  of 
contiguous  vertebras.  The  anterior  branch  of  the  corresponding 
cervical  nerve  separates  the  two  fasciculi.  In  the  dorsal  region 
these  muscles  in  the  upper  part  are  represented  by  small  round 
tendons,  but  in  the  three  lower  dorsal  vertebrae  they  again  become 
muscular  in  structure.  In  the  lumbar  region  the  muscular  fasciculi 


288  MUSCLES   OF   THE   BACK. 

are  four  in  number,  and  are  also  arranged  in  pairs  between  the 
transverse  processes.  Their  nerve-supply  is  derived  from  the 
internal  posterior  branches  of  the  cervical,  dorsal,  and  lumbar 
nerves. 

We  have  next  to  examine  the  muscles  concerned  in  the  move- 
ments of  the  head  upon  the  first  and  second  cervical  vertebras 
(fig.  68). 

FIG.  68. 


DRAWING    FROM    NATURE    OF    THE    SUBOCCIPITAL    TRIANGLE. 

1  and  7.  Complexus.  2.  Eectus  cap.  posticus  minor.  3.  Reotns  cap.  posticus  major.  4.  Obliquus 
inferior.  5.  Sterno-mastoid.  6.  Semispinalis  colli.  8.  Obliquus  superior.  10.  Splenms.  11. 
Trachelo-mastoid.  12.  Great  occipital  nerve.  13.  Occipital  artery  giving  off  its  descending 
branch — the  pnnceps  cer-eicis.  14.  Suboccipital  nerve.  15.  Third  cervical  nerve  (posterior 
branch). 

EECTUS  CAPITIS  This  is  a  largely  developed  interspinal  muscle. 
POSTICUS  MAJOR.  It  arises  by  a  small  tendon  from  the  well-marked 
spinous  process  of  the  second  cervical  vertebra,  and,  expanding  con- 
siderably, is  inserted  into  the  inferior  curved  ridge  of  the  occipital 
bone,  and  into  the  surface  of  bone  below  it.  These  recti  muscles, 
as  they  ascend,  one  on  each  side,  to  their  insertions,  diverge  and 
leave  an  interval  between  them  in  which  are  found  the  recti  capitis 
postici  minores. 


NERVES   OF   THE   BACK.  289 

EECTUS  CAPITIS  This  is  an  interspinal  muscle,  but  smaller  than 
POSTICUS  MINOR.  the  preceding.  Arising  from  the  posterior  tubercle 
of  the  first  vertebra,  it  expands  as  it  ascends,  and  is  inserted  into 
the  occipital  bone  between  the  inferior  curved  ridge  and  the  fora- 
men magnum.  The  action  of  the  two  preceding  muscles  is  to  raise 
the  head.  They  are  supplied  with  nerves  from  the'posterior  branch 
of  the  suboccipital. 

OBLIQUUS  This  arises  from  the  spinous  process  of  the  second 

INFERIOR.  cervical  vertebra,  and  is  inserted  into  the  transverse 

process  of  the  first.  Its  action  is  to  rotate  the  first  upon  the  second 
vertebra  :  in  other  words,  to  turn  the  head  round  to  the  same  side. 
It  is  supplied  with  a  nerve  by  the  great  occipital  (posterior  division 
of  the  second  cervical),  which  curves  up  under  its  lower  border. 

OBLIQUUS  This  muscle  arises  from  the  transverse  process 

SUPERIOR.  of  the  atlas,  and,  ascending  obliquely  inwards,  is 

inserted  in  the  interval  between  the  curved  ridges  of  the  occipital 
bone.  Its  action  is  to  draw  the  occiput  towards  the  spine. 

SUBOCCIPITAL  Observe  that  the  obliqui  (superior  and  inferior) 

TRIANGLE.  and  the  rectus  capitis  posticus  major  form  what 

is  called  the  suboccipital  triangle.  The  outer  side  is  formed  by  the 
obliquus  superior  ;  the  inner,  by  the  rectus  capitis  posticus  major  ; 
the  lower,  by  the  obliquus  inferior.  Within  this  triangle  may  be 
seen  the  arch  of  the  atlas,  the  vertebral  artery  lying  in  a  groove  on 
its  upper  surface,  and  the  posterior  occipito-atloid  ligament.  Be- 
tween the  artery  and  the  bone  appears  the  posterior  division  of  the 
suboccipital  nerve,  which  here  sends  branches  to  the  recti  postici, 
the  obliqui,  and  the  complexus :  that  is  to  say,  it  supplies  the 
muscles  which  form  the  triangle,  and  the  complexus  that  covers  it. 

EECTUS  CAPITIS  This  small  muscle  extends  between  the  trans- 
LATERALIS.  verse  process  of  the  first  vertebra  and  the  eminentia 

jugularis  of  the  occiput ;  but,  since  this  eminence  is  the  transverse 
process  of  the  occipital  vertebra,  the  muscle  should  be  considered 
as  an  intertransverse  one.  Its  nerve  comes  from  the  anterior 
division  of  the  suboccipital. 

NERVES  OF  THE  Th^  posterior  branches  of  the  spinal  nerves  sup- 
BACK.  ply  the  muscles  and  skin  of  the  back.  They  pass 

backwards  between  the  transverse  processes  of  the  vertebrae,  and 

u 


290  NERVES    OF   THE   BACK. 

divide  into  external  and  internal  branches.  The  general  plan  upon 
which  these  nerves  are  arranged  is  the  same  throughout  the  whole 
length  of  the  spine  ;  but,  since  there  are  certain  peculiarities  de- 
serving of  notice  in  particular  situations,  we  must  examine  each 
region  separately. 

CEKVICAL  The  posterior  division  of  the  first  cervical  nerve 

EEGION.  (the  suboccipital)  passes  between  the  arch  of  the 

atlas  and  the  vertebral  artery ;  it  then  enters  the  suboccipital 
triangle,  and  divides  into  branches  which  supply  the  muscles  :  one, 
which  passes  downwards  to  supply  the  inferior  oblique,  and  also 
sends  downwards  a  branch  to  communicate  with  the  second  cervical 
nerve ;  another  passes  upwards  to  supply  the  recti  capitis  major 
and  minor  ;  another  supplies  the  obliquus  superior  ;  another  enters 
the  com  plexus ;  and,  lastly,  a  cutaneous  branch  is  sometimes  given 
off  which  accompanies  the  occipital  artery,  and  is  distributed  to  the 
back  of  the  scalp. 

The  posterior  branch  (the  great  occipital)  of  the  second  cervical 
nerve  is  the  largest  of  the  series,  and  emerges  between  the  arches  of 
the  atlas  and  axis.  It  turns  upwards  beneath  the  inferior  oblique 
muscle,  passes  through  the  complexus,  and  runs  with  the  occipital 
artery  to  the  back  of  the  scalp. 

The  posterior  divisions  of  the  six  lower  cervical  nerves  divide 
into  external  and  internal  branches.  The  external  are  small,  and 
terminate  in  the  splenius,  and  the  continuation  of  the  erector  spinse 
—viz.,  the  trachelo-mastoid,  the  transversalis  colli,  and  the  cervicalis 
ascendens.  The  internal,  by  far  the  larger,  proceed  towards  the 
spinous  processes  of  the  vertebrae ;  those  of  the  third,  fourth,  and 
fifth  lie  between  the  complexus  and  the  semispinalis,1  and  after 
supplying  the  muscles  terminate  in  the  skin  over  the  trapezius  ; 
those  of  the  sixth,  seventh,  and  eighth  lie  between  the  semispinalis 
and  the  multifidus  spinae,  to  which  they  are  distributed,  and  do  not 
as  a  rule  give  off  any  cutaneous  branches. 

DORSAL  The  posterior  divisions  of  the  spinal  nerves  in 

EEGION.  this  region  come  out  between  the  transverse  pro- 

1  The  posterior  branches  of  the  second,  third,  and  fourth  nerves  are  generally 
connected,  beneath  the  complexus,  by  branches  in  the  form  of  loops.  This  consti- 
tutes ih&  posterior  cervical  plexus  of  some  anatomists. 


NERVES   OF   THE   BACK.  291 

cesses  and  the  tendons  attached  to  them.  They  soon  divide  into 
external  and  internal  branches.  The  external  pass  obliquely  over 
the  levatores  costarum,  between  the  ilio-costalis  and  the  longissimus 
dorsi ;  and  successively  increase  in  size  from  above  downwards. 
The  upper  six  terminate  in  the  erector  spinae  and  the  levatores  cos- 
tarum ;  the  lower  six,  after  supplying  these  muscles,  pass  through 
the  latissimus  dorsi,  and  become  the  cutaneous  nerves  of  the  back. 
The  internal  successively  decrease  in  size  from  above  downwards. 
They  run  towards  the  spine  between  the  semispinalis  dorsi  and  the 
multifidus  spinse.  The  upper  six,  after  giving  branches  to  the 
muscles,  perforate  the  trapezius  and  become  cutaneous  nerves.  The 
lower  ones  terminate  in  the  muscles  of  the  vertebral  groove. 

LUMBAR  The  general  arrangement  of  the  nerves  in  this 

REGION.  region  resembles  that  of  the  dorsal.     Their  external 

branches,  after  supplying  the  erector  spinae,  become  cutaneous  and 
terminate  in  the  skin  over  the  buttock.  The  internal  branches 
supply  the  multifidus  spinae. 

The  posterior  divisions  of  the  spinal  nerves  in 
SACRAL  REGION.  .          \  .         -nrM.1.  .0.  *.•          e  ^ 

this  region  are  small.      With  the  exception  or  the 

last,  they  come  out  of  the  spinal  canal  through  the  foramina  in  the 
back  of  the  sacrum.  The  upper  two  or  three  divide  into  external 
and  internal  branches.  The  internal  terminate  in  the  multifidus 
spinae ;  the  external  become  cutaneous  and  supply  the  skin  of  the 
gluteal  region.  The  last  two  sacral  nerves  proceed,  without  divi- 
ding, to  the  integument. 

The  coccygeal  nerve  is  exceedingly  small,  and,  after  joining  a 
small  branch  from  the  last  sacral,  terminates  in  the  skin  over  the 
coccyx. 

ARTERIES  OF  The   arteries  which  supply  the  back  are  : — 1 . 

THE  BACK.  Small   branches    from    the    occipital ;    2.    Small 

branches  from  the  vertebral;  3.  The  deep  cervical;  4.  The  pos- 
terior branches  of  the  intercostal  and  lumbar  arteries. 

The  occipital  artery  furnishes  several  small  branches  to  the 
muscles  at  the  back  of  the  neck ;  one,  larger  than  the  rest,  the 
arteria  princeps  cervicis,  descends  beneath  the  complexus,  and 
generally  inosculates  with  the  deep  cervical  artery,  and  with  small 
branches  from  the  vertebral. 

r  2 


FIG.  (59. 


a,  a,  Small  occipital  nerve 
from  the  cervical  plexus  ; 

1,  external      muscular 
branches  of  the  first  cer- 
vical nerve  and  union  by 
a  loop  with  the  second  ; 

2,  the  rectus  capitis  posti- 
cus  major,  with  the  great 
occipital    nerve    passing 
round,  the  short  muscles 
and    piercing   the    corn- 
plexus  ;     the      external 
branch    is    seen    to    the 
outside ;  2',  the  great  occi- 
pital ;  3,  external  branch 
of  the  posterior  primary 
division    of     the     third 
nerve ;    3',    its    internal 
branch,  or  third  occipital 
nerve  ;   4',  5',  6',   7',  8', 
internal  branches  of  the 
several        corn  spending 
nerves  on  the  left  side ; 
the  external  branches  of 
these   nerves  proceeding 
to  muscles  are  displayed 
on  the  right  side  :  d  1  to 
d  6,  and  thence  to  d  12,  ex- 
ternal muscular  branches 
of  the  posterior  primary 
divisions   of    the   twelve 
dorsal  nerves  on  the  right 
side  ;  d  I',  to  d  6',  the  in- 
ternal cutaneous  branches 
of  the  six  upper   dorsal 
nerves  on  the  left  side ; 
d  T  to  d  12',  cutaneous 
branches  of  the  six  lower 
dorsal  uerves  from  the  ex- 
ternal branches  ;  I,  I,  ex- 
ternal branches  of  the  pos- 
terior primary  branches 
of  several  lumbar  nerves 
on  the  right  side  piercing 
the   muscles,    the   lower 
descending  over  the  glu- 
teal  region ;  V,  I',  the  same 
more  superficially  on  the 
left  side';  *,  t,  on  the  right 
side,  the  issue  and  union 
by  loops  of  the  posterior 
primary  divisions  of  four 
sacral  nerves  ;  i',  s',  some 
of    these    distributed    to 
the  skin  on  the  left  side. 


DIAGKAM    OF    THE    CUTANEOUS    NERVES    OF    THE    BACK. 


PRE VERTEBRAL    MUSCLES.  293 

The  vertebral  artery  runs  along  the  groove  in  the  arch  of  the 
atlas,  and,  before  perforating  the  posterior  occipito-atloid  liga- 
ment to  enter  the  skull,  distributes  small  branches  to  the  adjacent 
muscles. 

The  deep  cervical  artery  is  the  posterior  branch  of  the  first 
intercostal  artery  (from  the  subclavian).  It  passes  backwards 
between  the  transverse  process  of  the  last  cervical  vertebra  and 
the  first  rib  :  it  then  ascends  between  the  complexus  and  the 
semispinalis  colli,  and  anastomoses  with  the  princeps  cervicis. 

The  posterior  branches  of  the  intercostal  and  lumbar  arteries 
accompany  the  corresponding  nerves,  and  are  in  all  respects 
similar  to  them  in  distribution.  Each  sends  a  small  branch  into 
the  spinal  canal  (intraspinal),  and  small  branches  to  the  vertebra. 

The  veins  correspond  to  the  arteries. 

PREVEKTEBKAL  We    have,   lastly,    to   examine  three    muscles, 

MUSCLES.  situated  in  front  of  the  spine  :  namely,  the  longus 

colli,  the  rectus  capitis  anticus  major,  and  the  rectus  capitis  anticus 
minor.  In  order  to  have  a  complete  view  of  the  two  latter,  a 
special  dissection  should  be  made,  before  the  head  is  removed  from 
the  first  vertebra. 

This  muscle  is  situated  in  front  of  the  spine, 
and  extends  from  the  third  dorsal  vertebra  to  the 
atlas.  For  convenience  of  description  it  is  divided  into  three  sets 
of  fibres,  of  which  one  extends  longitudinally  from  the  body  of 
one  vertebra  to  that  of  another ;  the  two  others  extend  obliquely 
between  the  transverse  processes  and  the  bodies  of  the  vertebrae. 

The  longitudinal  portion  of  the  muscle  arises  from  the  bodies 
of  the  three  upper  dorsal  and  the  three  lower  cervical  vertebrae, 
and  is  inserted  into  the  bodies  of  the  second,  third  and  fourth 
cervical  vertebrae. 

The  superior  oblique  portion,  arising  from  the  anterior  tubercles 
of  the  transverse  processes  of  the  third,  fourth,  and  fifth  cervical 
vertebrae,  ascends  inwards,  and  is  inserted  into  the  front  part  or 
body  of  the  atlas.  The  inferior  oblique  portion  proceeds  from  the 
bodies  of  the  three  upper  dorsal  vertebrae,  and  passing  upwards 
and  outwards,  is  inserted  into  the  transverse  processes  of  the  fifth 
and  sixth  cervical  vertebrae.  The  action  of  this  muscle,  taken  as  a 


294 


PRE VERTEBRAL   MUSCLES. 


whole,  must  be  to  bend  the  cervical  region  of  the  spine.    Its  nerves 
come  from  the  lower  cervical  nerves. 

RECTUS  CAPITIS  This  muscle  arises  by  tendinous  slips  from  the 
ANTICUS  MAJOR.  anterior  tubercles  of  the  transverse  processes  of 
the  third,  fourth,  fifth,  and  sixth  cervical  vertebras,  and,  ascending 

FIG.  70. 


DIAGRAM    OF    THE    PEEVEETEBEAL    MUSCLES. 


1-7.  The  bodies  of  the  cervical  vertebrae  : 
below  ore  the  bodies  of  the  three 
upper  dorsal  vertebrae. 

a.  Bectus  capitis  lateralis. 

6.  Rectus  capitis  anticns  major. 

c.  Bectus  capitis  anticus  minor. 


d.  Intertransverse  muscle. 

e.  Scalenus  anticus. 
/.  Scalenus  medius. 
g.  Longus  colli. 

h.  Scalenus  posticus. 


obliquely  inwards,  is  inserted  into  the  basilar  process  of  the  occipital 
bone,  in  front  of  the  foramen  magnum. 

RECTUS  CAPITIS  This  muscle  arises  from  the  front  of  the  root  of 
ANTICUS  MINOR.  the  transverse  process  of  the  atlas,  and  is  inserted 
into  the  basilar  process  of  the  occipital  bone,  nearer  to  the  foramen 
magnum  than  the  preceding  muscle.  The  action  of  the  recti 


LIGAMENTS   OF   THE   SPINE.  295 

muscles  is  to  bend  the  head  forwards.  They  are  supplied  with 
nerves  from  the  anterior  division  of  the  suboccipital,  and  from  the 
deep  cervical  plexus. 

LIGAMENTS   OF   THE    SPINE. 

The  vertebras  are  connected  by  their  intervertebral  fibre-carti- 
lages, by  ligaments  in  front  of  and  behind  their  bodies,  and  by 
ligaments  which  extend  between  their  arches  and  their  spines. 
Their  articular  processes  have  capsular  ligaments,  and  synovial 
membranes. 

ANTERIOR  COM-  This  is  a  strong  broad  band  of  longitudinal 
MON  LIGAMENT.  fibres  which  extends  along  the  front  of  the  bodies 
of  the  vertebrae,  from  the  axis  to  the  sacrum.  The  ligament  is 
broader  below  than  above,  thickest  in  the  dorsal  region,  and  its 
fibres  are  more  firmly  adherent  to  the  intervertebral  cartilages  and 
to  the  borders  of  the  vertebrae,  than  to  the  middle  of  the  bones. 
The  fibres  are  not  all  of  equal  length  ;  the  more  superficial  extend 
from  one  vertebra  to  the  fourth  or  fifth  below  it ;  those  a  little 
deeper  pass  from  one  vertebra  to  the  second  or  thir;l  below  it ; 
while  the  deepest  of  all  proceed  from  vertebra  to  vertebra.  Above, 
it  is  attached  to  the  axis  by  a  pointed  process,  where  it  is  con- 
nected with  the  longus  colli,  and  it  is  thicker  over  the  bodies  of 
the  vertebra  than  over  the  intervertebral  cartilages,  thus  filling  up 
the  concavities  of  the  bodies  and  rendering  the  surface  more  smooth 
and  even. 

POSTERIOE  COM-  This  extends  longitudinally,  in  a  similar  man- 
MON  LIGAMENT.  ner  to  the  anterior  common  ligament,  within  the 
spinal  canal,  along  the  posterior  surface  of  the  bodies  of  the 
vertebrae,  from  the  axis  to  the  sacrum.  It  is  broader  above  than 
below,  and,  like  the  anterior  ligament,  is  thickest  in  the  dorsal 
region,  and  is  more  intimately  connected  with  the  intervertebral 
fibro-cartilages  than  with  the  bodies  of  the  vertebrae.  It  sends 
up  a  prolongation  to  the  anterior  border  of  the  foramen  magnum 
continuous  with  the  apparatus  ligamentosus. 

INTEBSPINOUS  These  bands  of  ligamentous  fibres  fill  up  the 

LIGAMENTS.  intervals  between  the  spines  of  the  dorsal  and 


296  LIGAMENTS   OF  THE   SPINE. 

lumbar   vertebras.     They   are    the   most    marked   in   the   lumbar 
SUPRASPINOUS        region.     Those  fibres  which    connect   the   apices 
LIGAMENT.  of  the  spines,  being  stronger  than  the  rest,  are 

described  as  a  separate  ligament  under  the  name  of  supraspinous. 
It  extends  from  the  spinous  process  of  the  seventh  cervical  to  the 
spine  of  the  sacrum  ;  and  is  strongest  in  the  lumbar  region.  Their 
use  is  to  limit  the  flexion  of  the  spine. 

LIGAMENTS  These   are  called,  on  account  of  their  colour, 

BETWEEN  THE  ligamenta   subflava.     To    obtain    a  good  view   of 

ARCHES  OF  THE  them,  the  arches  of  the  vertebrae  should  be  re- 
moved with  a  saw,  and  the  ligaments  should  be 
seen  from  within,  since  viewed  from  without  they  are  to  a  large 
extent  hidden  by  the  overlapping  laminae.  They  pass  between  the 
laminae  of  the  contiguous  vertebrae,  from  the  axis  to  the  sacrum ; 
none  existing  between  the  occiput  and  the  atlas,  or  between  the 
atlas  and  the  axis.  Each  ligament  consists  of  two  halves  which 
are  attached  to  the  corresponding  half  laminae  above  and  below  on 
each  side.  They  are  composed  of  yellow  elastic  tissue,  the  fibres 
being  arranged  vertically,  and  their  strength  increases  with  the 
size  of  the  vertebrae.  This  elasticity  answers  a  double  purpose  :  it 
not  only  permits  the  spine  to  bend  forwards,  but  materially  assists 
in  restoring  it  to  its  curve  of  rest.  They  economise  muscular  force, 
like  the  ligamentum  nuchae  in  animals. 

INTERVERTE-  This   substance,  placed  between  the  bodies  of 

BRAL  FIBRO-  the  vertebrae,  is  by  far  the  strongest  bond  of  con- 

CARTILAGE.  nection  between  them,  and  fulfils  most  important 

purposes  in  the  mechanism  of  the  spine.  Its  peculiar  structure  is 
adapted  to  break  shocks,  and  to  render  the  spine  flexible  and 
resilient.  To  see  the  structure  of  an  intervertebral  fibro-cartilage, 
a  horizontal  section  must  be  made  through  it.  It  is  firm  and 
resisting  near  the  circumference,  but  soft  and  pulpy  towards  the 
centre.  The  circumferential  portion  is  composed  of  concentric 
layers  of  fibro-cartilage,  placed  vertically.  These  layers  are 
attached  by  their  edges  to  the  vertebrae ;  they  gradually  decrease 
in  number  from  the  circumference  towards  the  centre ;  and  the 
interstices  between  them  are  filled  by  soft  pulpy  tissue.  The 
central  portion  is  composed  almost  entirely  of  this  pulpy  tissue ; 


INTERVERTEBRAL   FIBRO-CARTILAGES.  297 

and  it  bulges  when  no  longer  under  pressure.  Thus  the  bodies 
of  the  vertebras,  in  their  motions  upon  each  other,  revolve  upon 
an  elastic  cushion  tightly  girt  all  round  by  bands  of  fibrous  tissue. 
These  motions  are  regulated  by  the  articular  processes. 

Dissect  an  intervertebral  substance  layer  after  layer  in  front, 
and  you  will  find  that  the  circumferential  fibres  extend  obliquely 
between  the  vertebrae,  crossing  each  other  like  the  branches  of  the 
letter  X  (fig.  72). 

The  thickness  of  the  intervertebral  cartilages  is  not  the  same 
in  front  and  behind.  It  is  this  difference  in  their  thickness,  more 
than  that  in  the  bodies  of  the  vertebrae,  which  produces  the  several 
curves  of  the  spine.  In  the  lumbar  and  cervical  regions  they  are 
thicker  in  front ;  in  the  dorsal  region,  behind. 

The  structure  of  the  intervertebral  cartilages  explains  the  well- 
known  fact  that  a  man  becomes  shorter  after  standing  for  some  hours  ; 
and  that  he  regains  his  usual  height  after  rest.  The  difference  between 
the  morning  and  evening  stature  amounts  to  more  than  half  an  inch. 

It  also  explains  the  fact  that  a  permanent  lateral  curvature  of  the 
spine  may  be  produced  (especially  in  the  young)  by  the  habitual  practice 
of  leaning  to  this  or  that  side.  Experience  proves  that  the  cause  of 
lateral  curvature  depends  more  frequently  upon  some  alteration  in  the 
structure  of  the  fibro-cartilages  than  upon  the  bones.  From  an  exami- 
nation of  the  bodies  of  one  hundred  and  thirty-four  individuals  with 
crooked  spines,  it  was  concluded  that,  in  two-thirds,  the  bones  were 
perfectly  healthy  ;  that  the  most  frequent  cause  of  curvature  resided 
in  the  intervertebral  substances,  these  being,  on  the  concave  side  of  the 
curve,  almost  absorbed,  and,  on  the  convex  side,  preternatu rally  deve- 
loped. As  might  be  expected  in  these  cases,  the  muscles  on  the  convex 
side  become  lengthened,  and  degenerate  in  structure.1 

LIGAMENTUM  This  ligament  is  a  thin  fibrous  septum  inter- 

NUCH;E.  mingled  with  elastic  tissue,  situated  in  the  middle 

line,  and  extends  from  the  spinous  processes  of  the  cervical  ver- 
tebrae to  the  external  occipital  protuberance.  It  forms  an  inter- 
muscular  septum  down  the  back  of  the  neck,  and  may  be  regarded 
as  the  continuation  upwards  of  the  supraspinous  ligament. 

CAPSULAB  Each  joint  between  the  articular  processes  has 

LIGAMENTS.  a  synovial  membrane  surrounded  by  loose  liga- 

1  On  this  subject  see  Hildebrandt's  Anatomic,  B.  ii.  s.  155. 


298  LIGAMENTS   BETWEEN   OCCIPITAL   BONE   AND   ATLAS. 

mentous  fibres,  forming  a  capsular  ligament  which  is  longest  in 
the  cervical  vertebras,  thus  allowing  free  movement  in  this  region. 
The  surfaces  of  the  bones  are  crusted  with  cartilage. 

INTEKTKANS-  These  are  thin  bands  of  fibres  which  pass  be- 

VEESE  LIGAMENTS,  tween  the  transverse  processes  of  the  vertebras. 
They  are  rudimentary  in  the  cervical  region,  and  are  sometimes 
absent. 

MOVEMENTS  OP  Though  but  little  movement  is  permitted  be- 

THE  SPINE.  tween  any  two  vertebras  (the  atlas  and  axis  ex- 

cepted),  yet  the  collective  motion  between  them  all  is  considerable. 
The  spine  can  be  bent  forwards,  backwards,  or  on  either  side  ;  it 
also  admits  of  slight  rotation.  In  consequence  of  the  elasticity  of 
the  intervertebral  cartilages  and  the  ligamenta  subflava,  it  returns 
spontaneously  to  its  natural  curve  of  rest  like  an  elastic  bow.  Its 
mobility  is  greatest  in  the  cervical  region,  on  account  of  the  thick- 
ness of  the  fibro-cartilages,  the  small  size  of  the  vertebras,  the 
oblique  direction  of  their  articulations,  and,  above  all,  the  horizontal 
position  and  the  shortness  of  their  spines.  In  the  dorsal  region 
there  is  very  little  mobility,  on  account  of  the  vertical  direction  of 
the  articular  processes,  and  the  manner  in  which  the  arches  and 
the  spines  overlap  each  other.  In  the  lumbar  region,  the  spine 
again  becomes  more  moveable,  on  account  of  the  thickness  of  the 
intervertebral  cartilages,  and  the  horizontal  direction  of  the  spinous 
processes. 

LIGAMENTS  BE  ^e  occiput  is  connected  to  the  atlas  by  the 

TWEEN  THE  Occipi-  following  ligaments  :  viz.  two  anterior  occipito- 
TAL  BONE  AND  atloid,  a  posterior  occipito-atloid,  two  lateral 

THE  ATLAS.  occipito-atloid,  and  two  capsular  ligaments. 

The  two  anterior  ligaments  are  composed  of  a  superficial  and  a 
deep  portion  ;  the  superficial  part  is  a  strong  rounded  cord  which 
passes  from  the  basilar  process  above,  to  the  tubercle  on  the  ante- 
rior arch  of  the  atlas  below  ;  the  deep  portion  is  membranous,  and 
passes  from  the  anterior  margin  of  the  foramen  magnum  to  the 
front  arch  of  the  atlas. 

The  posterior  ligament  extends  in  a  similar  manner  from  the 
posterior  border  of  the  foramen  magnum  to  the  posterior  arch  of 
the  atlas.  It  is  thin,  and  superiorly  becomes  blended  with  the 


LIGAMENTS   BETWEEN   OCCIPITAL   BONE   AND   AXIS. 


299 


dura  mater,  and  is  pierced  by  the  vertebral  artery  and  the   sub- 
occipital  nerve. 

The  two  lateral  ligaments  pass  from  the  jugular  eminences  of 
the  occiput,  downwards  and  outwards  to  the  transverse  processes  of 
the  atlas. 

The  capsular  ligaments  extend  from  the  margin  of  the  condyles 
of  the  occipital  bone  to  the  upper  articular  borders  of  the  atlas. 

The  movements  which  take  place  between  the  occipital  bone 
and  the  atlas  are  flexion  and  extension,  as  in  nodding  forwards  and 
backwards ;  and  lateral  movement,  as  in  inclining  the  head  side- 
ways. 

FIG.  71. 


POST?  COMMON    LICT 


DIAGRAM   OF   THE    ODONTOID   AND   TRANSVERSE   LIGAMENTS. 

LIGAMENTS  These  are  the  most  important ;  and  to  see  them, 

BETWEEN  THE  the  spinal  canal  must  be  exposed  by  removing  the 

OCCIPITAL  BONE         posterior  arches  of  the  upper  cervical  vertebrae,  and 

AND  THE  AXIS.  j.1  •  T  i    •    i      •       i 

tne  posterior  common  ligament,  which  is  here  very 
thick  and  strong.  It  ascends  from  the  posterior  surface  of  the 
axis,  then  passes  over  the  odontoid  and  transverse  ligaments,  and 
is  attached  to  the  basilar  process  of  the  occipital  bone.  It  is  called 
the  occipito-axial  ligament,  or  the  apparatus  ligamentosus  colli. 

ODONTOID  OR  The  odontoid  or  check  ligaments  (fig.    71)  are 

CHECK  LIGAMENTS,     two  very  strong  ligaments,  which   proceed  from 
the  sides  of  the  odontoid  process  to  the  tubercles  on  the  inner 


300  ATLO-AXIAL    LIGAMENTS. 

sides  of  the  condyles  of  the  occiput.  Their  use  is  to  limit  the 
rotation  of  the  head.  A  third  or  middle  odontoid  ligament  passes 
from  the  apex  of  the  odontoid  process  to  the  margin  of  the  foramen 
magnum.  It  is  sometimes  called  the  ligamentum  suspefoorium. 

ARTICULATION  Tllis  Joint  forms  a  lateral  ginglvmus  or  diar- 

BETWEEN  THE  throsis  rotatoria,  and  is  maintained  by  the  follow- 

ATLAS  AND  THE  ing  ligaments  :  two  anterior  atlo-axial,  a  posterior 
atlo-axial,  two  capsular,  and  a  transverse. 

The  two  anterior  ligaments  consist  of  a  superficial  and  a  deep 
portion :  the  superficial  is  a  rounded  ligament  passing  from  the 
tubercle  of  the  atlas  to  the  base  of  the  odontoid  process ;  the  deep 
passes  as  a  membranous  layer  from  the  anterior  arch  of  the  atlas 
to  the  body  of  the  axis. 

The  posterior  ligament  extends  from  the  posterior  arch  of  the 
atlas  to  the  upper  border  of  the  lamina  of  the  axis. 

The  capsular  ligaments  are  thin  loose  ligamentous  sacs  connect- 
ing the  borders  of  the  articular  surfaces. 

The  transverse  ligament  (fig.  71)  passes  transversely  behind 
the  odontoid  process,  and  is  attached  to  the  tubercles  on  the  inner 
sides  of  the  articular  processes  of  the  atlas.  From  the  centre  of 
this  ligament  a  few  fibres  pass  upwards,  to  be  attached  to  the 
basilar  process,  and  some  downwards  to  the  body  of  the  axis,  giving 
it  a  cruciform  appearance.  Thus  it  forms  with  the  atlas  a  ring, 
into  which  the  odontoid  process  is  received.  If  this  transverse 
ligament  be  divided,  we  observe  that  the  odontoid  process  is  covered 
with  cartilage  in  front  and  behind,  and  is  provided  with  two 
synovial  membranes. 

The  ribs  articulate  by  their  heads  with  the  bodies  of  the  dorsal 
vertebrse ;  by  their  necks  and  tubercles  with  the  transverse  pro- 
cesses of  the  vertebrae,  and  by  their  cartilages  with  the  sternum  in 
front. 

The  head  of  each  rib  presents  two  articular  sur- 
ARTICULATIONS  .  r 

OF  THE  HEADS  OF  faces,  corresponding  to  the  bodies  of  two  vertebras. 
THE  EIBS  WITH  There  are  two  distinct  articulations,  each  provided 

THE  BODIES  OF  with  a  separate  synovial  membrane.  The  ligaments 
THE  VERTEBRAE. 

are — 

1 .  An  anterior  costo-central  or  stellate,  which  connects  the  front 


COSTO-VERTEBRAL   LIGAMENTS. 


of  the  head  of  the  rib  with  the  sides  of  the  bodies  of  two  vertebra; 
and  the  intervening  fibre-cartilage  (fig.  72).  It  is  composed  of  three 
fasciculi  of  fibres  which  radiate  from  the  rib,  one  of  which  passes 
upwards  to  be  attached  to  the  body  of  the  vertebra  above ;  the  lower 
one  passes  to  the  body  of  the  vertebra  below  ;  while  the  intermediate 
one  passes  horizontally  forwards  to  the  intervertebral  disc. 

In  the  three  lower  ribs  the  fasciculi  are  not  separately  distin- 
guishable, although  the  fibres  pass  upwards  to  the  vertebree  and 
downwards  to  the  vertebra  with  which  the  rib  articulates. 

Some  anatomists  describe  a  capsular  ligament  surrounding  the 
articulation ;  the  fibres  are  very  thin,  and  form  part  of  the  costo- 
central  ligament. 

FIG.  72. 


1,  1,  1.    Superior    costo- 
transverse  ligaments. 


2,  2,  2.  Anterior  costo-con- 
tral  or  stellate  ligaments. 


COSTO-VEKTEBEAL    LIGAMENTS. 


2.  An  interarticular  ligament  which  passes  across  the  joint  from 
the  ridge  on  the  head  of  the  rib  to  the  iutervertebral  cartilage.  It 
divides  the  articulation  into  two  joints  which  do  not  communicate 
with  each  other.  It  is  absent  in  the  three  lower  articulations. 

The  ligaments  connecting  these  bones  are  the 
capsular,  the  anterior,  middle  and  posterior  costo- 
transverse. 

The  capsular  ligament  surrounds  the  articular 
surfaces  of  the  tubercle  of  the  rib  and  the  transverse 
process  of  its  corresponding  vertebra,  and  has  a 
synovial  membrane.     It  is  absent  in  the  eleventh  and  twelfth  ribs. 
The  anterior  or  superior  costo-transverse  ligament  ascends  from 


ABTICULATIONS 
OF  THE  NECK  AND 
TUBERCLE  OF  THE 

KlBS  WITH  THE 

TRANSVERSE  PRO- 
CESSES. 


302 


COSTO-STERNAL   LIGAMENTS. 


the  upper  border  of  the  neck  of  the  rib  to  the  lower  border  of  the 
transverse  process  above  it.  It  is  continuous  externally  with  the 
aponeurosis  covering  the  external  intercostal  muscle.  The  first  and 
twelfth  ribs  have  no  anterior  costo-trans verse  ligament  (fig.  72). 

The  middle  costo-transverse  ligament  is  an  interosseous  one,  and 
connects  the  adjacent  surfaces  of  the  neck  of  the  rib,  and  the  trans- 
verse process.  It  is  badly  developed  in  the  eleventh  and  twelfth 
ribs  (fig.  73). 

The  posterior  costo-transverse  ligament  passes  from  the  apex  of 
the  transverse  process  to  the  summit  of  the  tubercle  of  the  rib.  It 
is  wanting  in  the  eleventh  and  twelfth  ribs  (fig.  73). 

FIG.  73. 


DIAGRAM   SHOWING   THE    LIGAMENTS   CONNECTING   THE    KIB   WITH    THE    VERTEBRA. 


1.  The  anterior  costo-ccntral  ligament. 

2.  The  interosseous,  or  middle  costo-transverse 

ligament. 


3.  The  posterior  costo-transverse  ligament. 

4.  The  synovial  membrane  between  the  rib  and 

the  body  of  the  vertebra. 


CONNECTION 
BETWEEN  THE 
CARTILAGES  OF 

THE  ElBS  AND 

STERNUM. 


The  anterior  extremities  of  the  ribs  are  concave, 
and  receive  the  cartilages  of  the  ribs  ;  this  junction 
is  maintained  by  the  periosteum.  The  cartilages 
of  all  the  true  ribs  are  received  into  slight  con- 
cavities on  the  side  of  the  sternum,  and  are  se- 
cured by  anterior,  posterior,  upper,  and  lower  ligaments.  There  is 
a  synovial  membrane  between  the  cartilage  of  each  rib  and  the 
sternum,  except  that  of  the  first,  and  usually  at  each  articulation 
the  synovial  membrane  is  separated  into  two  by  an  interarticular 
ligament. 

The  costal  cartilages  from  the  sixth  to  the  tenth  are  connected  by 


TEMPORO-MAXILLARY   ARTICULATION.  303 

ligamentous  fibres.  There  are  intercostal  synovial  membranes  in 
front  between  the  adjacent  borders  of  the  sixth,  seventh,  eighth, 
and  ninth  costal  cartilages. 

MOVEMENTS  OF  The  movements  permitted  between  the  heads  of 

THE  BIBS.  the  ribs  and  the  bodies  of  the  vertebrae  are  those 

of  elevation  and  depression,  and  those  of  rotation  forwards  and 
backwards ;  the  centre  of  these  movements  being  at  the  interarticu- 
lar  ligament.  Between  the  tubercles  and  the  transverse  processes 
there  is  the  movement  of  an  arthrodial  nature ;  and  between  the 
costal  cartilages  and  the  sternum,  that  of  elevation  and  depression. 

The  movement  of  the  first  rib  is  very  slight ;  that  of  the  second 
is  freer ;  and  mobility  of  the  ribs  gradually  increases  from  above 
downwards. 

ARTICULATION  The  condyle  of  the  lower  jaw  articulates  with 

OF  THE  LOWER  the  glenoid  cavity  of  the  temporal  bone,  and  forms 
JAW-  an  arthrodial  joint.  The  joint  is  provided  with  an 

interarticular  fibre-cartilage,  with  external  and  internal  lateral  and 
capsular  ligaments,  and  two  synovial  membranes  (fig,  74). 

The  external  lateral  ligament  extends  from  the  zygoma  and  its 
tubercle ;  its  fibres  pass  downwards  and  backwards  to  the  outer 
surface  and  posterior  border  of  the  neck  of  the  jaw. 

The  internal  lateral  ligament — a  long,  thin,  flat  band — extends 
from  the  spinous  process  of  the  sphenoid  bone  to  the  inner  border 
of  the  dental  foramen. 

The  capsular  ligament  consists  of  a  few  scattered  fibres  attached 
above  to  the  margin  of  the  glenoid  cavity,  below  to  the  neck  of  the 
jaw. 

The  interarticular  fibro-cartilage  is  a  thin  plate  of  an  oval  form, 
and  thicker  at  the  margin  than  at  the  centre.  It  is  placed  hori- 
zontally, and  its  upper  surface  is  concavo-convex  from  before  back- 
wards ;  its  lower  surface  is  concave.  It  is  connected  on  the  outer 
side  to  the  external  lateral  ligament,  and  on  the  inner  side  some  of 
the  fibres  of  the  external  pterygoid  muscle  are  inserted  into  it. 

There  are  two  synovial  membranes — an  upper  and  a  lower — for 
the  joint.  The  larger  and  looser  of  the  two  is  situated  between  the 
glenoid  cavity  and  the  fibro-cartilage.  The  lower  is  interposed 
between  the  fibro-cartilage  and  the  condyle  of  the  jaw.  They 


304 


TEMPORO-MAXILLARY    ARTICULATION. 


sometimes  communicate  through  a  small  aperture  in  the  centre  of 
the  fibro-cartilage. 

The  form  of  the  articulation  of  the  lower  jaw  admits  of  move- 
ment, upwards  and  downwards,  forwards,  backwards,  and  from  side 
to  side.  A  combination  of  these  movements  takes  place  in  masti- 
cation :  during  this  act  the  condyles  of  the  jaw  describe  an  oblique 
rotatory  movement  in  the  glenoid  cavity.  The  purposes  served  by 
the  fibro-cartilage  in  this  joint  are  : — first,  it  follows  the  condyle, 

FIG.  74. 


Section  through  the  glenoid  cavity 
Interarticular  fibro-cartilage      .    . 


Internal  lateral  ligament  .    .     .    .  _ 


TRANSVERSE  SECTION  TO  SHOW  THE  LIGAMENTS  AND  THE  FIBRO-CARTILAGE  OF  THE 
JOINT  OF  THE  LOWER  JAW.  THE  DOTTED  LINES  REPRESENT  THE  TWO  SYNOVIAL 
MEMBRANES. 

and  interposes  a  convenient  socket  for  all  its  movements  :  second, 
being  elastic,  it  breaks  shocks  ;  for  shocks  here  would  be  almost 
fatal,  considering  what  a  thin  plate  of  bone  the  glenoid  cavity  is, 
and  that  just  above  it  is  the  brain.  Its  nerves  are  derived  from 
the  auriculo-temporal,  and  the  masseteric  branches  of  the  inferior 
maxillary. 

The  stylo-hyoid  and  stylo-maxillary  ligaments  have  been  pre- 
viously described. 


305 


DISSECTION  OF  THE   UPPER  EXTREMITY. 

THE  subject  should  be  placed  on  its  back,  and,  the  thorax  being 
raised  by  a  block  placed  under  the  shoulders,  the  arm  is  to  be  ex- 
tended to  a  right  angle  with  the  trunk  and  slightly  rotated  out- 
wards. A  narrow  board  must  be  placed  under  the  arm  to  keep  it 
in  position,  and  the  hand,  with  the  palm  upwards,  is  to  be  firmly 
encircled  by  string  to  the  board. 

SURFACE  Before  commencing  the  dissection  of  the  arm, 

MARKING.  the  student  should  carefully  examine  with  the  eye 

and  the  finger  the  various  inequalities  of  the  surface  of  the  skin, 
which  are  caused  by,  or  are  landmarks  of,  important  subjacent 
structures. 

Beginning  in  the  middle  line,  we  notice  a  broad  shallow  groove 
in  front  of  the  sternum  between  the  sternal  origins  of  the  pectoralis 
major ;  about  two  inches  below  the  upper  border  of  the  sternum  is 
a  prominent  transverse  bony  ridge  (angulus  sterni),  which  cor- 
responds to  the  junction  of  the  first  and  second  portions  of  the 
sternum. 

The  clavicle  may  be  easily  traced,  convex  as  to  its  sternal  half, 
and  concave  in  its  outer  half;  not  placed  quite  horizontally,  but 
inclined  upwards  in  the  present  position  of  the  limb,  and  articula- 
ting externally  with  the  prominent  acromion  process.  Extending 
obliquely  downwards  and  outwards,  from  the  middle  of  the  clavicle, 
is  a  groove,  marking  the  separation  between  the  contiguous  borders 
of  the  deltoid  and  pectoralis  major,  and  in  which  may,  by  deep  pres- 
sure, be  felt  the  coracoid  process.  Another  groove,  passing  outwards 
from  the  sterno-clavicular  joint,  indicates  the  interval  between  the 
sternal  and  clavicular  attachments  of  the  pectoralis  major.  The  upper 
arm  below  the  acromion  is  rounded,  the  convexity  being  caused  by 
the  greater  and  lesser  tuberosities  of  the  humerus.  In  the  more 

x 


306  CUTANEOUS  NERVES  OF  THE  CHEST. 

common  forms  of  dislocations  of  the  humerus,  this  roundness  is  lost, 
and  a  depression  takes  its  place.  Between  the  thorax  and  the  arm 
there  is  a  deep  hollow — the  axilla — which  varies  according  to  the 
position  of  the  arm  to  the  side.  Its  front  border  is  formed  by  the 
pectoralis  major,  and  its  hinder  border  by  the  latissinms  dorsi  ;  and 
if  the  fingers  be  pushed  up  into  this  space,  the  head  of  the  humerus 
can  be  easily  felt.  The  free  border  of  the  pectoralis  major  muscle 
corresponds  with  the  fifth  rib,  and  below  this  can  be  distinguished 
the  lower  digitations  of  the  serratus  magnus  with  the  external 
oblique. 

The  student  must  now  make  three  incisions 
through  the  skin :  the  first,  along  the  middle  of 
the  whole  length  of  the  sternum  ;  the  second,  along  the  lower 
border  of  the  clavicle,  and  down  along  the  front  of  the  upper  arm 
for  four  inches  ;  the  third,  from  the  ensiform  cartilage,  backwards 
to  the  posterior  border  of  the  axilla. 

The  skin  should  now  be  taken  up  with  the  forceps  at  the  upper 
and  inner  angle,  and  when  the  skin  has  been  so  far  reflected  as  to 
enable  the  fingers  to  take  it  up,  lay  aside  the  forceps  and  use  the 
fingers  in  their  place.  The  skin  should  be  carefully  dissected  from 
the  subjacent  layer  of  subcutaneous  fascia  and  fat.  In  doing  so, 
notice  the  thin,  pale  fibres  of  the  broad  subcutaneous  muscle  of  the 
neck — platysma  my  aides  (fig.  13). 

Beneath  this  subcutaneous  fascia  and  fat  there  is  the  strong 
deep  fascia  which  closely  invests  the  muscles,  and  in  the  axilla  it 
forms  a  dense  fascia  which  passes  from  the  pectoralis  major  to  the 
latissimus  dorsi. 

CUTANEOUS  The  numerous  nerves  which  run  through  the 

NEKVES.  subcutaneous   tissue   to  the  skin  and  mammary 

gland  must  be  carefully  dissected  out.  They  are  derived  from 
various  sources  :  some,  branches  of  the  superficial  cervical  plexus, 
descend  over  the  clavicle  ;  others,  branches  of  the  intercostal  nerves, 
come  through  the  intercostal  spaces  close  to  the  sternum,  each  with 
a  small  artery ;  a  third  series,  also  branches  of  the  intercostal  nerves, 
come  out  on  the  side  of  the  chest,  and  run  forwards  over  the  outer 
border  of  the  pectoralis  major. 

The  supra-clavicular   nerves,  which  arise  from  the  third  and 


CUTANEOUS  NERVES  OF  THE  CHEST.  307 

fourth  cervical  nerves,  descend  over  the  clavicle,  and  are  subdivided, 
according  to  their  direction,  into  sternal,  clavicular,  and  acromial 
branches  (diagram,  p.  66).  The  inner  or  sternal  cross  the  inner 
end  of  the  clavicle  to  supply  the  skin  over  the  upper  part  of  the 
sternum.  The  middle  or  clavicular  pass  over  the  middle  of  the  cla- 
vicle, and  supply  the  integument  over  the  front  of  the  chest  and 
the  mammary  gland.  The  outer  or  acromial  branches  cross  over 
the  outer  end  of  the  clavicle,  and  distribute  their  filaments  to  the 
skin  of  the  shoulder. 

Near  the  sternum  are  found  the  anterior  cutaneous  branches  or 
terminal  filaments  of  the  intercostal  nerves.  After  piercing  the  in- 
ternal intercostal  and  pectoralis  major  muscles,  each  nerve  sends  an 
inner  filament  to  the  skin  over  the  sternum,  and  an  outer  larger 
one,  which  supplies  the  skin  over  the  pectoral  muscle.  Those  of 
the  third  and  fourth  intercostal  supply  also  the  mammary  gland. 

Branches  of  the  internal  mammary  artery,  for  the  supply  of  the 
mammary  gland,  accompany  these  nerves.  During  lactation  they 
increase  in  size,  ramifying  tortuously  over  the  surface  of  the  gland. 
They  are  occasionally  as  large  as  the  radial  at  the  wrist. 

The  lateral  cutaneous  branches  of  the  intercostal  nerves  come  out 
between  the  digitations  of  the  serratus  magnus  on  the  side  of  the 
chest,  and  divide  into  anterior  and  posterior  branches.  The  anterior 
branches  curve  round  the  free  border  of  the  pectoralis  major,  and 
then  supply  the  skin  over  that  muscle  and  the  mamma.  The  pos- 
terior branches  supply  the  skin  of  the  back  of  the  chest. 

Dissect  off  the  superficial  fascia  and  fat  with  the 

DlSSFCTION 

mammary  gland.  Thus  you  will  expose  the  strong 
deep  fascia  which  is  closely  attached  to  the  pectoralis  major  and 
deltoid  muscles.  It  is  continuous,  above,  with  the  fascia  of  the 
neck ;  below,  with  that  of  the  arm.  At  the  axilla  it  becomes  denser, 
where  it  passes  from  the  pectoral  to  the  latissimus  dorsi  muscles. 

Reflect  this  fascia  from  the  pectoralis  major  by  dissecting 
parallel  with  the  course  of  its  fibres.  The  muscle  having  been 
fully  exposed,  observe  its  shape,  the  course  of  its  fibres,  their  origin 
and  insertion.1 

1  Sometimes  we  find  a  thin  little  muscle  running  perpendicularly  in  front  of 
the  inner  part  of  the  pectoralis  major.  This  is  the  rectus  sternalis  or  sternalis 


308  PECTORALIS   MAJOR. 

PECTOKALIS  The  pectoralis  major   is   the   large    triangular 

MAJOK.  muscle  in  the  front  of  the  chest.     It  arises  from 

the  anterior  surface  of  the  sternal  half  of  the  clavicle,  from  the  front 
of  its  own  half  of  the  sternum,  from  the  cartilages  of  all  the  true 
ribs  except  the  last,  and  from  the  aponeurosis  of  the  external  oblique 
muscle  of  the  abdomen.  From  this  extensive  origin  the  fibres 
converge  towards  the  arm,  the  upper  ones  passing  downwards  and 
outwards,  the  middle  ones  transversely  outwards,  and  the  lower 
fibres  upwards  and  outwards ;  they  terminate  in  a  flat  tendon, 
about  two  inches  in  breadth,  which  is  inserted  into  the  anterior 
margin  of  the  bicipital  groove  of  the  humerus.  The  arrangement 
of  its  fibres,  as  well  as  the  structure  of  its  tendon,  is  peculiar.  The 
lower  fibres,  which  form  the  boundary  of  the  axilla,  are  folded  be- 
neath the  rest,  and  terminate  upon  the  upper  part  of  the  tendon — 
i.e.  nearer  to  the  shoulder-joint ;  the  upper  fibres,  which  arise  from 
the  clavicle,  and  are  frequently  separated  from  the  main  body  of 
the  muscle  by  a  slight  interval,  descend  in  front  of  the  lower,  and 
terminate  upon  the  lower  part  of  the  tendon.  Consequently  the 
upper  and  lower  fibres  of  the  muscle  cross  each  other  previously  to 
their  insertion. 

The  object  of  this  arrangement  is  to  enable  all  the  fibres  to  act 
simultaneously  when  the  arm  is  extended. 

The  upper  part  of  the  tendon  sends  off  a  fibrous  prolongation, 
which  binds  down  the  long  head  of  the  biceps,  and  is  attached  to 
the  great  tuberosity  of  the  humerus ;  another  tendinous  expansion 
is  prolonged  backwards  to  the  tendon  of  the  deltoid  muscle ;  and  a 
third  passes  downwards  to  be  intimately  connected  with  the  fascia 
of  the  upper  arm. 

The  chief  action  of  the  pectoralis  major  is  to  draw  the  humerus 
towards  the  chest,  as  in  placing  the  hand  on  the  opposite  shoulder, 
or  in  pulling  an  object  towards  the  body.  When  the  arm  is  raised 
and  made  the  fixed  point,  the  muscle  assists  in  raising  the  trunk, 
as  in  climbing.  Thus  too,  on  emergency,  it  can  act  as  an  auxiliary 
muscle  of  inspiration. 

Between  the  pectoralis  major  and  the  deltoid,  the  great  muscle- 

brutorum.     It  arises  inferiorly  by  a  tendinous  expansion  from   the   reotus  ab- 
dominis,  and  is  connected  above  to  the  tendon  of  the  sterno-mastoid. 


INFRA- CLAVICULAR  REGION.  309 

covering  the  shoulder,  is  an  interval  varying  in  extent  in  different 
subjects,  but  always  more  marked  towards  the  clavicle.  It  contains 
a  small  artery — the  thoracica  humeraria — and  the  cephalic  vein, 
•which  ascends  on  the  outer  side  of  the  arm,  and  empties  itself  into 
the  axillary.  This  interval  is  the  proper  place  to  feel  for  the  cora- 
coid  process.  In  doubtful  injuries  about  the  shoulder,  this  point 
of  bone  is  a  good  landmark  in  helping  the  surgeon  to  arrive  at  a 
correct  diagnosis. 

The  pectoralis  major  is  supplied  with  nerves  by  the  anterior 
thoracic  branches  of  the  brachial  plexus ;  with  blood,  by  the  long 
and  short  thoracic  branches  of  the  axillary  artery. 

DISSECTION  Reflect   the   clavicular   part    of  the    pectoralis 

ANATOMY  OP  THE  major  by  detaching  it  from  the  clavicle,  and  turn 
INFKA-CLAVICULAR  it  downwards  ;  in  doing  so,  notice  a  small  nerve, 
EEGION.  ^  external  anterior  thoracic,  which  enters  the 

under  surface  of  this  part  of  the  muscle.  Beneath  the  portion 
thus  reflected,  part  of  the  pectoralis  minor  will  be  exposed.  In 
this  triangle — bounded,  above,  by  the  clavicle  ;  below,  by  the  upper 
border  of  the  sternal  origin  of  the  pectoralis  major ;  and,  on  the 
outer  side,  by  the  deltoid — is  an  important  space  in  which  the 
relative  position  of  the  following  objects  must  be  carefully  ex- 
amined : — 

COSTO-COBACOID          «•  A  strong  ligamentous  expansion,  called  the 
MEMBRANE.  costo-coracoid   membrane,  extends    from    the  car- 

tilage of  the  first  rib  to  the  coracoid  process.  Between  these 
points  it  is  attached  to  the  clavicle,  and  forms  a  complete  investment 
for  the  subclavius  muscle.  Its  lower  crescent-shaped  edge  arches 
over,  and  protects  the  axillary  vessels  and  nerves  ;  from  this  edge 
is  prolonged  downwards  a  funnel-shaped  fascia,  which  covers  the 
axillary  vessels,  forming  the  anterior  portion  of  their  sheath ;  the 
posterior  being  formed  by  a  prolongation  of  the  deep  cervical 
fascia.  The  front  portion  of  this  sheath  is  perforated  by  the 
cephalic  vein,  the  thoracica  acromialis  artery  and  vein,  the  ante- 
rior thoracic  nerves,  and  the  superior  thoracic  artery.  This  fascia 
must  be  removed. 

b.  The  subclavius  muscle  enclosed  in  its  fibrous  sheath. 

c.  The  axillary  vein,  artery,  and  brachial  plexus  of  nerves. 


810  INFRA-CLAVICULAR   REGION. 

d.  Two  arteries,  the  superior  or  short  thoracic  and  the  thoracica 
acromialis. 

e.  The  termination  of  the  cephalic  vein  in  the  axillary. 

/.  Two  nerves,  the  anterior  thoracic,  which  descend  from  the 
brachial  plexus  below  the  clavicle,  and  cross  in  front  of  the  axillary 
vessels  to  supply  the  pectoral  muscles. 

This  muscle  lies  between  the  clavicle  and  the 

first  rib.  It  arises  from  the  first  rib  by  a  short 
round  tendon  at  the  junction  of  the  bone  and  cartilage  in  front  of 
the  costo- clavicular  ligament,  and  is  inserted  into  the  groove  on 
the  under  surface  of  the  clavicle  as  far  outwards  as  the  coraco- 
clavicular  ligament.  Its  nerve  comes  from  the  fifth  and  sixth 
cervical  nerves.  Its  action  is  to  depress  the  clavicle,  and  prevent 
its  too  great  elevation. 

EELAT   E  POSI  ^n  ^e  infra-clavicular  space  before  us  are  the 

TION  OF  THE  AXIL-  great  vessels  and  nerves  of  the  axilla  in  the  first 
LAKY  VESSELS  AND  part  of  their  course.  They  lie  at  a  great  depth 

from  the  surface.  They  are  surrounded  by  a 
sheath  of  fascia,  which  descends  with  them  beneath  the  clavicle. 
Their  relations  with  regard  to  each  other  are  as  follows :  The 
axillary  vein  lies  in  front  of  the  artery,  and  rather  to  its  thoracic 
side.  The  brachial  plexus  of  nerves  is  situated  above  the  artery, 
and  on  a  posterior  plane.  The  plexus  consists  of  two,  or  some- 
times three,  large  cords,  which  result  from  the  union  of  the 
anterior  branches  of  the  four  lower  cervical,  and  the  first  dorsal , 
nerves.  The  course 'and  relations  of  the  axillary  artery  will  be 
examined  subsequently. 

SUPERIOR  These   are   two   branches   which    arise   from    the 

THORACIC  AND  axillary  artery  in  the  first  part  of  its  course,  above 

ACROMIO-THORACIC  the  pectoralis  minor.  The  superior  thoracic  fre- 
ARTERIES.  quently  arises  in  common  with  the  acromio-thoracic, 

and  passing  along  the  upper  border  of  the  pectoralis  minor,  descends 
between  this  muscle  and  the  pectoralis  major,  supplying  both  and  ana- 
stomosing with  the  intercostal  and  internal  mammary  arteries.  The 
thoracica  acromialis  is  given  off  just  above  the  pectoralis  minor,  and 
shortly  divides  into  three  sets  of  branches :  viz.  two  or  three  small 
thoracic  branches  to  the  serratus  magnus  and  pectoral  muscles ;  the 
thoracica  Jmmeraria,  which  descends  with  the  cephalic  vein,  in  the 


INFRA-CLAVICULAR   REGION.  311 

interval  between  the  pectoralis  major  and  deltoid,  and  ramifies  in  both  ; 
and,  lastly,  the  acromial  branch,  which  passes  over  the  coracoid  process 
to  the  under  surface  of  the  deltoid,  which  it  supplies,  and  communicates 
with  the  posterior  circumflex,  a  branch  of  the  axillary,  and  the  supra- 
scapular,  a  branch  of  the  subclavian.  A  constant  though  small  branch, 
the  clavicular,  runs  along  the  anterior  aspect  of  the  subclavius.  All 
these  arteries  are  accompanied  by  veins,  which  most  frequently  empty 
themselves  into  the  cephalic,  but  occasionally  into  the  axillary  vein. 

The  cephalic  vein  is  one  of  the  principal  cuta- 
CEPHALIC  VEIN.  .  „    , ,  ^  .  , , 

neous  veins   of   the    arm.     Commencing   on   the 

back  of  the  thumb  and  forefinger,  it  runs  up  the  radial  side  of  the 
forearm,  in  front  of  the  elbow-joint ;  thence  ascending  along  the 
outer  edge  of  the  biceps,  it  runs  up  the  interval  between  the  pec- 
toralis major  and  deltoid,  pierces  the  costo-coracoid  membrane, 
crosses  over  the  axillary  artery,  and  finally  empties  itself  into  the 
axillary  vein.1 

ANTERIOR  THO-  These  nerves  come  from  the  brachial  plexus 
RACIC  NERVES.  below  the  clavicle  to  supply  the  pectoral  muscles. 
There  are  generally  two — an  external  and  an  internal — one  for 
each  pectoral  muscle.  The  external,  the  more  superficial,  arises 
from  the  outer  cord  of  the  brachial  plexus,  passes  over  the  axillary 
artery  and  vein,  pierces  the  costo-coracoid  membrane,  and  supplies 
the  pectoralis  major  on  its  under  aspect :  it  communicates  with 
the  next  nerve  by  a  filament  which  forms  a  loop  on  the  inner  side 
of  the  artery ;  the  internal,  and  smaller  branch,  comes  from  the 
internal  cord,  and  descends  between  the  axillary  artery  and  vein 
(occasionally  through  the  vein)  to  supply  the  pectoralis  minor  on 
its  under  surface. 

DIFFICULTY  OF  From  this  view  of  the  relations  of  the  axillary 

TYING  THE  FIRST  artery  in  the  first  part  of  its  course,  some  idea 
PABT  OF  THE  AXIL-  may  \)Q  formed  of  the  difficulty  of  passing  a 
ligature  round  it  in  this  situation.  In  addition 
to  its  great  depth  from  the  surface,  varieties  sometimes  occur  in  the 
position  of  the  nerves  and  veins,  which  render  the  operation  still 

1  The  cephalic  vein,  in  some  cases,  runs  over  the  clavicle  to  join  the  external 
jugular  ;  or  there  may  be  a  communication  (termed  jugulo-cephalic)  between  these 
veins. 


312  DISSECTION   OF  THE   AXILLA. 

more  embarrassing.  For  instance,  the  anterior  thoracic  nerves 
may  be  more  numerous  than  usual,  and  form  by  their  mutual 
communication  a  plexus  around  the  artery.  A  large  nerve  is 
often  seen  crossing  obliquely  over  the  artery,  immediately  below 
the  clavicle,  to  form  one  of  the  roots  of  the  median  nerve.  The 
cephalic  vein  may  ascend  higher  than  usual,  and  open  into  the 
subclavian ;  and  as  it  receives  large  veins  corresponding  to  the 
thoracic  axis,  a  concourse  of  veins  would  be  met  with  in  front  of 
the  artery.  Again,  it  is  by  no  means  uncommon  to  find  a  deep- 
seated  vein,  the  supra-scapular,  crossing  over  the  artery  to  join 
the  axillary  vein. 


DISSECTION   OF   THE  AXILLA. 

SEBACEOUS  On  the  under  surface  of  the  skin  of  the  axilla, 

GLANDS.  near  the  roots  of  the  hairs,  are  numerous  sebaceous 

glands.  They  are  of  a  reddish-brown  colour,  and  rather  larger 
than  a  pin's  head. 

AXTLLABY  This  dense  fascia,  which  lies  immediately  be- 

FASCIA.  neath  the  skin  of  the  axilla,  is  a  continuation  of 

the  general  fascia!  investment  of  the  muscles.  It  closes  in  and 
forms  the  floor  of  the  cavity  of  the  axilla.  Externally,  it  is 
strengthened  by  fibres  from  the  tendons  of  the  pectoralis  major 
and  latissimus  dorsi,  and  is  continuous  with  the  fascia  of  the  arm  ; 
internally,  it  is  prolonged  on  the  side  of  the  chest,  over  the  serratus 
magnus  muscle ;  in  front  and  behind,  it  divides,  so  as  to  enclose 
between  its  layers  the  muscles  which  form  the  boundaries  of  the 
axilla.  Thus  the  anterior  layer  encloses  the  two  pectoral  muscles, 
and  is  connected  with  the  coracoid  process,  the  costo-coracoid 
ligament,  and  the  clavicle ;  the  posterior  layer  encloses  the  latis- 
simus dorsi,  and  passes  backwards  to  the  spine. 

A  subcutaneous  artery,  sometimes  of  considerable  size,  is  often 
found  in  the  substance  of  the  axillary  fascia.  It  generally  arises 
from  the  brachial,  or  from  the  lower  part  of  the  axillary  artery,  and 
runs  across  the  floor  of  the  axilla  towards  the  lower  edge  of  the  pecto- 
-ralis  major.  It  is  not  a  named  branch,  but  should  be  remembered, 


BOUNDARIES   OF  THE   AXILLA.  313 

as  it  would  occasion  much,  haemorrhage  if  wounded  in  opening  an 
abscess. 

DISSECTION  AND  Reflect  the  axillary  fascia,  to  display  the 
CONTENTS  OF  THE  boundaries  and  the  contents  of  the  axilla.  The 
AXILLA.  dissection  of  this  space  is  difficult,  and  must  be 

done  cautiously.  Bear  in  mind  that  the  trunk  blood-vessels  and 
nerves  run  through  the  upper  and  outer  part  of  the  axilla ;  that 
the  long  thoracic  artery  runs  along  the  anterior  border,  and  the 
subscapular  artery  along  the  posterior.  Commence  dissecting, 
therefore,  in  the  middle;  break  down  with  the  handle  of  the 
scalpel  the  loose  connective  tissue,  fat,  and  lymphatic  glands, 
which  occupy  the  cavity.  You  will  soon  discover  some  cutaneous 
nerves  coming  out  between  the  ribs,  and  then  crossing  the  axillary 
space.  These  nerves  are  the  posterior  lateral  cutaneous  brandies 
of  the  intercostal  nerves ;  they  perforate  the  intercostal  spaces  be- 
tween the  digitations  of  the  serratus  magnus,  midway  between 
the  sternum  and  the  spine,  and  divide  into  anterior  and  posterior 
branches.  The  anterior  turn  over  the  pectoralis  major,  to  supply 
the  skin  on  the  front  of  the  chest  and  the  mammary  gland.  The 
posterior  pass  backwards  over  the  latissimus  dorsi,  and  are  distri- 
buted to  the  skin  covering  this  muscle  and  the  scapula. 

INTEECOSTO-  The  posterior  lateral  branch  of  the  second  inter- 

HUMERAL  NEBVES.  costal  nerve  requires  a  special  description.  It  is 
larger  than  the  others,  and  is  called  the  intercosto-lmmeral  because 
it  supplies  the  integuments  of  the  arm.  It  comes  through  the 
second  intercostal  space,  traverses  the  upper  part  of  the  axilla, 
where  it  receives  a  branch  of  the  lesser  internal  cutaneous  nerve 
(nerve  of  Wrisberg),  and,  piercing  the  fascia,  terminates  in  fila- 
ments, which  are  distributed  to  the  skin  on  the  inner  side  and 
back  of  the  arm,  as  low  as  the  internal  condyle.  The  correspond- 
ing branch  of  the  third  intercostal  is  also  an  intercosto-lmmeral 
nerve.  It  receives  a  branch  from  the  second,  and  runs  a  similar 
course.  The  distribution  of  these  nerves  accounts  for  the  pain 
down  the  arm  which  is  sometimes  experienced  in  pleurisy. 

BOUNDABIES  OF  The  axilla  is  a  conical  space,  of  which  the  apex. 

THE  AXILLA.  is  beneath  the  clavicle,  and  the  base  between  the 

pectoralis  major  and  the  latissimus  dorsi.     Obviously  it  varies  in ./ 


314  PECTORALIS   MINOR. 

capacity  according  to  the  position  of  the  arm  to  the  side.  On  the 
inner  side,  it  is  bounded  by  the  four  upper  ribs,  with  their  corre- 
sponding intercostal  muscles  and  the  serratus  magnus  ;  on  the 
outer,  by  the  humerus,  covered  by  the  coraco-brachialis  and  biceps ; 
in  front,  by  the  pectoral  is  major  and  minor ;  behind,  by  the  latis- 
simus  dorsi,  teres  major,  and  subscapularis.  Its  anterior  and 
posterior  boundaries  converge  from  the  chest,  so  that  the  axilla 
becomes  narrower  towards  the  arm.  With  a  full  view  of  the  axilla 
before  you,  bear  in  mind  that  pus  may  burrow  under  the  pectoral 
muscles,  or  under  the  scapula,  or  that  it  may  run  up  beneath  the 
clavicle  and  point  in  the  neck,  if  the  abscess  be  allowed  to  remain 
unopened. 

AXILLARY  LYMPH-       The  axillary  glands  form  a  continuous  chain, 
ATIC  GLANDS.  beneath   the    clavicle,  with   the  cervical    glands. 

They  are  from  ten  to  twelve  in  number,  of  a  reddish-brown  colour, 
and  variable  size.  Most  of  them  lie  near  the  axillary  vessels  ; 
others  are  embedded  in  the  loose  tissue  of  the  axilla ;  sometimes 
one  or  two  small  ones  are  observed  along  the  lower  border  of  the 
pectoralis  major.  They  are  supplied  with  blood  by  a  branch — 
thoracica  alaris — of  the  axillary  artery,  and  by  branches  from  the 
thoracic  and  subscapular  arteries. 

These  glands  receive  the  lymphatics  from  the  arm,  from  the 
front  and  side  of  the  chest,  and  from  the  outer  half  of  the  mam- 
mary gland.  It  is  these  glands  which  frequently  become  enlarged 
in  cancer  of  the  mammary  gland.  From  these  glands  the  efferent 
lymphatics  pass  along  with  the  subclavir.n  artery  and  terminate,  on 
the  right  side,  in  the  right  lymphatic  duct ;  and,  on  the  left  side, 
in  the  thoracic  duct. 

Now  cut  through  the  pectoralis  maior,  about 
DISSECTION.  A 

the  middle,  and  turn  the  inner  part  of  the  muscle 

towards  the  sternum,  and  the  outer  part  towards  the  arm.  The 
pectoralis  minor  is  thus  exposed,  together  with  the  ramifications  of 
the  short  and  long  thoracic  arteries.  Preserve  the  arteries,  as  far 
as  possible,  in  connection  with  the  main  trunks. 

PECTOBALIS  This  triangular  muscle  arises   from  the   third, 

MINOK.  fourth,  and  fifth  ribs,  near  the  costal  cartilages, 

and  from  the  thick  fascia  over  the  intercostal  spaces.     The  fibres 


AXILLARY   ARTERY.  315 

run  obliquely  upwards  and  outwards,  and  converge  to  a  strong 
tendon,  which  is  inserted  into  the  anterior  surface  of  the  coracoid 
process.  The  tendon  is  connected  to  that  of  the  coraco-brachialis 
and  biceps  by  a  strong  fascia,  which  forms  a  protection  for  the 
subjacent  axillary  vessels  and  nerves.  The  action  of  this  muscle  is 
to  draw  the  scapula  downwards  and  forwards.  Its  nerve  is  derived 
from  the  internal  anterior  thoracic. 

Having  examined  the  muscles  which  form  the 

anterior  boundary  of  the  axilla,  we  pass  now  to 

the  course  and  relations  of  the  axillary  artery  and  its  branches. 

To  have  a  clear  view,  reflect  the  subclavius  from  its  insertion,  and 

cut  the  pectoralis  minor  through  its  middle. 

AXILLABY  AR-  This  artery,  the  continuation  of  the  subclavian, 

TERY,  ITS  COURSE  takes  the  name  of  axillary  at  the  outer  border  of 
AND  RELATIONS.  ^g  grs^  j-j^  j^  then  passes  downwards  and  out- 
wards, through  the  upper  part  of  the  axilla,  beneath  the  two  pec- 
toral muscles,  and  along  the  inner  border  of  the  coraco-brachialis, 
as  far  as  the  lower  border  of  the  tendon  of  the  teres  major,  beyond 
which  it  is  continued  under  the  name  of  the  brachial.  Its  course 
is  divided  for  convenience  of  description  into  three  parts  :  the  first 
lies  above  the  pectoralis  minor ;  the  second  behind  that  muscle  ; 
and  the  third  below  it. 

In  the  first  part  of  its  course,  the  artery  is  covered  by  the  pec- 
toralis major  and  the  costo-coracoid  membrane,  the  subclavius,  and 
is  crossed  by  the  cephalic  and  acromio-thoracic  veins.  On  its  inner 
side,  and  slightly  in  front,  is  the  axillary  vein  ;  on  its  outer  side  is 
the  brachial  plexus  of  nerves  ;  behind  it,  are  the  first  intercostal 
space,  the  second  digitation  of  the  serratus  magnus,  and  the  pos- 
terior thoracic  nerve  (external  respiratory  of  Bell). 

In  the  second  part  of  its  course,  it  lies  behind  the  pectoralis 
major  and  minor;  on  its  inner  side  is  the  axillary  vein,  still  slightly 
anterior,  but  separated  from  the  artery  by  the  inner  cord  of  the 
brachial  plexus ;  on  its  outer  side  is  the  outer  cord  of  the  brachial 
plexus ;  and  behind  it,  is  the  posterior  cord  of  the  plexus,  and  also 
a  quantity  of  loose  connective  tissue  which  separates  it  from  the 
subscapularis  muscle.  The  inner  head  of  the  median  nerve  is  often 
in  front  of  the  artery  in  this  part  of  its  course. 


316  AXILLARY   ARTERY. 

In  the  third  part,  in  front  of  the  artery,  are  the  pectoralis  major, 
the  two  roots  of  the  median  nerve,  converging  like  the  letter  V ; 
and  lower  down  is  the  skin  and  the  fascia  of  the  arm ;  on  the  outer 

FIG.  75. 


DIAGRAM    OF    AXILLA. 

1.  Axillary  artery.  8.  Superior  prof unda  a. 

2.  Brachial  artery.  9.  Posterior  thoracic  nerve. 

3.  Thoracica  humeraria  a.  10.  Long  subscapular  n. 

4.  Superior  thoracic  a.  11.  Median  n. 

5.  Subscapular  a.  12.  Cephalic  vein. 

6.  Dorsalis  scapulae  a.  13.  Muscujp-cutaueous  n. 

7.  Posterior  circumflex  a.                                    14.  Teres  major. 

side  are  the  coraco-brachialis,  the  musculo-cutaneous  and  median 
nerves ;  on  the  inner  side  are  the  axillary  vein,  the  ulnar,  and  the 


BRANCHES    OF   THE    AXILLARY    ARTERY. 


317 


two  internal  cutaneous  nerves ;  behind  it  are,  in  succession,  the 
subscapularis,  the  latissimus  dorsi,  the  teres  major,  and  the 
musculo-spiral  and  circumflex  nerves. 

BRANCHES  OF  The  number  and  origin  of  these  branches  often 

THE  AXILLARY  vary,  but  their  general  course  is  in  most  cases 

ARTERY.  similar,  and  they  usually  arise  in  the  following 

order : — 

a.  The   superior   thoracic   arises  above   the  pectoralis   minor,  and 
divides  into  branches,  which  have  been  already  described  (p.  310). 

b.  The  acromial  thoracic   also  arises   above   the   pectoralis   minor, 
and  gives  off  numerous  branches  already  described  (p.  310). 

c.  The  alar  thoracic,  variable  in  its  origin,  supplies  the  lymphatic 
glands  and  the  connective  tissue  of  the  axilla. 


PLAN    OF    THE    BRANCHES    OF    THE    AXILLARY    ARTERY. 


1.  Thoracic  axis,  giving  off— 

2.  Short  thoracic. 

3.  Thoracica  acromialis. 

4.  Thoracica  humeraria. 
5.  Long  thoracic. 


6.  Subscapular. 

7.  Dorsalis  scapula?. 

8.  Anterior  circumflex. 

9.  Posterior  circumflex. 


d.  The  inferior  or  long  thoracic  artery  (external  mammary)  runs 
along  the  lower  border  of  the  pectoralis  minor  to  the  side  of  the  chest. 
It  supplies   the   mammary  gland,   the  serratus  maggus  and  pectoral 
muscles,   and  maintains  a  free   anastomosis  with  the  short  thoracic, 
internal  mammary,  and  intercostal  arteries. 

e.  The  subscapular  is  the  largest  branch  of  the  axillary  •  it  arises 
opposite  the  lower  border  of   the   subscapularis,  and,  after  running  a 
short'  course  of  about  an  inch  and  a  half,  divides  into  an  anterior  and 
posterior  branch. 

The  anterior  branch  runs  along  the  anterior  edge  of  the  subscapu- 


318 


BRANCHES    OF    THE    AXILLARY    ARTERY. 


laris  towards  the  lower  angle  of  the  scapula.  Its  numerous  branches 
supply  the  subscapularis,  latissimus  clorsi,  serratus  magnus,  and  teres 
major,  and  anastomose  with  the  intercostal  and  thoracic  arteries,  and 
with  the  posterior  scapular  (a  branch  of  the  subclavian). 

The  posterior  branch  (dorsalis  scapulae)  runs  to  the  back  of  the 
scapula,  through  a  triangular  space,  bounded  in  front  by  the  long  head 
of  the  triceps;  below,  by  the  teres  major  ;  and,  above,  by  the  subscapu- 
laris and  teres  minor  (diagram,  p.  318).  It  gives  off  a  small  branch 
which  enters  the  subscapular  fossa  beneath  the  subscapularis,  supplying 
it,  and  anastomosing  with  the  suprascapular  and  posterior  scapular 
arteries.  On  the  back  of  the  scapula  it  divides  into  two  branches  :  one 

FIG.  77. 


1.  Subscapularis. 

2.  Teres  major. 

3.  Long  head  of  triceps. 

4.  Square  space  for  post. 

circumflex  a.  and  n. 


5.  Triangular  space  for  dor- 

salis scapulas  a. 

6.  Space  for  musculo-spiral 

n.,  and   superior    pro- 
funda  a. 


DIAGRAM    OF    THE    ORIGINS    OF    THE    TRICEPS. 

runs  in  the  groove  on  the  axillary  border  of  the  scapula,  lying  beneath 
the  teres  minor,  and  ramifies  in  the  infraspinous  fossa  between  the  bone 
and  the  infraspinatus  ;  the  other  runs  down  between  the  teres  minor 
and  major  on  their  dorsal  aspects,  and  passes  to  the  inferior  angle  of 
the  scapula,  anastomosing  with  the  posterior  and  suprascapular  arteries. 
The  subscapular  vein  empties  itself  into  the  axillary  vein. 

f.  The  posterior  circumflex  artery  arises  from  the  back  of  the  axillary 
artery,  and  is  as  large  as  the  subscapular,  close  to  which  it  is  given  off  ] 
or  both  may  arise  by  a  common  trunk  from  the  axillary.  It  passes 
backwards,  with  its  corresponding  veins  and  nerve,  through  a  quadri- 
lateral space,  bounded  above  by  the  subscapularis  and  teres  minor, 
below  by  the  teres  major,  externally  by  the  neck  of  the  humerus,  and 


BRACHIAL    PLEXUS    OF    NERVES.  319 

internally  by  the  long  head  of  the  triceps  (fig.  77).  It  then  winds 
round  the  back  of  the  neck  of  the  humerus,  and  is  chiefly  distributed  to 
the  under  surface  of  the  deltoid. 

Besides  the  deltoid,  the  posterior  circumflex  artery  supplies  the  long 
head  of  the  triceps,  the  head  of  the  humerus,  and  the  shoulder- joint. 
It  inosculates  above  with  the  acromio- thoracic  and  suprascapular 
arteries,  below  with  the  ascending  branch  of  the  superior  profunda  (a 
branch  of  the  brachial),  and  in  front  with  the  anterior  circumflex 
artery.  Should  you  not  find  the  posterior  circumflex  artery  in  its 
normal  position,  look  for  it  (as  a  branch  of  the  brachial)  below  the 
tendon  of  the  teres  major. 

g.  The  anterior  circumflex  artery,  much  smaller  than  the  posterior, 
runs  in  front  of  the  neck  of  the  humerus,  above  the  tendon  of  the 
latissimus  dorsi.  It  passes  directly  outwards  beneath  the  coraco- 
brachialis  and  short  head  of  the  biceps,  close  to  the  bone,  and  terminates 
in  the  under  surface  of  the  deltoid,  where  it  inosculates  with  the 
posterior  circumflex. 

The  anterior  circumflex  artery  sends  a  small  branch  which  runs 
with  the  long  tendon  of  the  biceps  up  the  groove  of  the  humerus,  and 
is  called,  on  that  account,  the  bicipital  artery.  It  supplies  the  shoulder- 
joint  and  the  neck  of  the  humerus. 

If  the  axillary  were  tied  below  the  pectoralis  minor,  the  colla- 
teral circulation  would  be  established  by  the  suprascapular,  and  its 
branches  anastomosing  with  the  subscapular,  the  dorsalis  scapulae, 
and  the  posterior  circumflex ;  the  posterior  scapular  with  the  dor- 
salis scapulas  and  subscapular  arteries.1 

The  axillary  vein  is  formed  by  the  continuation 
upwards  of  the  basilic  vein,  and  extends  from  the 
lower  border  of  the  teres  major  to  the  outer  border  of  the  first  rib. 
It  receives  the  venae  comites  of  the  brachial  artery  near  the  lower 
border  of  the  subscapularis.  It  receives  the  subscapular  and  the 
other  veins  corresponding  to  the  branches  of  the  axillary  artery, 
with  the  exception  of  the  circumflex,  which  usually  join  either 
the  subscapular  or  one  of  the  venae  comites.  The  axillary  near  its 
termination  also  receives  the  cephalic  vein. 

1  The  axillary  artery  varies  much  as  to  the  branches  it  gives  off  :  occasionally 
(1  in  33)  it  gives  off  the  radial  artery ;  more  rarely  (1  in  72)  it  gives  off  the  ulnar  ; 
and  more  rarely  still  (1  in  506)  it  gives  off  the  interosseous  artery. 


BRACHIAL  PLEXUS  OF  NERVES. 


The  axillary  vein  in  the  upper  part  of  its  course  lies  in  front  of 
the  artery,  and  close  to  its  sternal  side ;  in  the  lower  two-thirds  of 
its  course,  the  vein  lies  still  to  the  sternal  side  of  the  artery,  but  is 
separated  from  it  by  some  of  the  nerves  of  the  brachial  plexus. 

AXILLARY  OR  This  plexus  is  formed  by  the  anterior  trunks  of 

BRACHIAL  PLEXUS      the  four  lower  cervical  and  first*dorsal  nerves,  and 
receives  also  a  small  communicating  branch  from 

FIG.  78. 


OF  NERVES. 


THE    BRACHIAL   PLEXUS    OF    NERVES. 


c  4-8.  The  five  lower  cervical  nerves. 
D  1.  The  first  dorsal  nerve. 
9.  The  rhomboid  nerve— to  rhomboidei 
major  and  minor. 

10.  The  supra-scapular  nerve— to  supra 

and  infra  spinati. 

11.  The  nerve  to  the  subclavius. 

12.  Outer  anterior  thoracic    nerve — to 

pectoralis  major. 

13.  Inner  anterior  thoracic    nerve — to 

pectoralis  minor. 


14, 15, 16.  The  sutscapular  nerves — to  subscapu- 
laris,  latissimus  clorsi,  and  teres  major. 

17.  Lesser  internal  cuianeous  nerve. 

18.  Musculo-cutaneous  nerve. 

19.  Musculo- spiral  nerve. 

20.  Median  nerve. 

21.  Circumflex  nerve— to  deltoid  and  teres 

minor. 

22.  Ulnar  nerve. 

23.  Internal  cutaneous  nerve. 

24.  External  respiratory  nerve  of  Bell,  or 

posterior  thoracic. 


the  fourth  cervical  nerve.  The  plexus  is  broad  at  the  lower  part 
of  the  neck,  where  it  emerges  between  the  anterior  and  middle 
scalene  muscles  ;  but  it  gradually  contracts  as  it  descends  beneath 


BRACHIAL  PLEXUS  OF  NERVES.  321 

the  clavicle  into  the  axilla,  and  on  a  level  with  the  coracoid  process 
distributes  its  large  branches  to  the  upper  limb. 

The  arrangement  of  the  cervical  nerves  in  the  formation  of  the 
plexus  is  variable,  often  not  alike  on  both  sides.1  The  most  fre- 
quent disposition  is  this — the  fifth  and  sixth  cervical  unite  at  the 
outer  border  of  the  scalenus  medius  to  form  an  upper  cord ;  the 
eighth  and  the  first  dorsal  form  between  the  scaleni  muscles  a  lower 
cord  ;  the  seventh  cervical  runs  alone,  as  a  middle  cord,  for  a  short 
distance.  Each  of  these  nerves  divides,  just  external  to  the  outer 
border  of  the  scalenus  medius,  into  an  anterior  and  a  posterior 
branch  ;  the  anterior  branches  given  oif  from  the  fifth,  sixth,  and 
seventh  cervical  form  the  outer  cord  of  the  plexus  ;  the  anterior 
branches  given  off  from  the  eighth  cervical  and  the  first  dorsal  form 
the  inner  cord  ;  while  the  posterior  branches  of  all  the  nerves — viz., 
the  fifth,  sixth,  seventh,  eighth  cervical,  and  the  first  dorsal — unite 
to  form  the  posterior  cord. 

At  first  these  cords  are  placed  on  the  outer  side  of  the  axillary 
artery,  but  behind  the  pectoralis  minor  they  are  situated  one  on  the 
outer  side  of,  one  on  the  inner  side  of,  and  one  behind,  the  axillary 
artery. 

The  brachial  plexus  gives  off  some  branches  above  the  clavicle, 
which  were  dissected  with  the  neck  (p.  125).  Below  the  clavicle, 
it  gives  off  the  following  : — 

From  the  outer  cord  proceed  an  anterior  thoracic  branch,  the 
musculo-cutaneous,  and  the  outer  head  of  the  median  ;  from  the 
inner  cord  proceed  the  inner  anterior  thoracic  nerve,  the  inner 
head  of  the  median,  the  ulnar,  the  internal  cutaneous,  and  the 
lesser  internal  cutaneous  ;  from  the  posterior  cord  proceed  the  three 
subscapular  nerves,  the  circumflex,  and  the  musculo-spiral. 

The  anterior  thoracic  nerves  have  been  described  (p.  311). 
SUBSCAPULAR  The  three  subscapular  nerves  are  found  on  the 

NEKVES.  surface  of  the  subscapularis.     They  come  from  the 

posterior  cord  of  the  brachial  plexus,  and  supply,  respectively,  the 
latissimus  dorsi,  teres  major,  and  subscapularis.  The  nerve  to  the 
latissiinus  dorsi  (long  subscapular  nerve)  runs  with  the  anterior 

1  Frequently  the  second  dorsal  nerve  sends  upwards  a  communicating  filament 
to  the  first  dorsal  nerve.     (Journal  of  Anatomy,  vol.  xi.  p.  539.) 


322  LATISSIMUS   DORSI. 

branch  of  the  subscapular  artery  to  the  lower  border  and  inner 
surface  of  the  muscle. 

The  nerve  to  the  teres  major  is  either  a  branch  of  the  preceding, 
or  comes  separately  from  the  posterior  cord.  It  lies  nearer  to  the 
hunierus  than  the  long  subscapular.  It  gives  off  also  a  small  branch 
to  the  anterior  border  of  the  subscapularis. 

The  nerve  to  the  subscapulans  arises  from  the  posterior  cord, 
higher  than  the  others,  and  enters  the  muscle  not  far  from  its  upper 
border  in  company  with  a  small  artery. 

CIRCUMFLEX  The  circumflex  nerve  accompanies  the  posterior 

NERVE.  .     circumflex  artery.     This  large  nerve  comes  from  the 

posterior  cord,  and,  after  giving1  a  small  filament  to  the  shoulder- 
joint,  passes,  with  its  companion  artery,  through  the  quadrilateral 
space  (p.  318)  to  the  under  surface  of  the  deltoid.  Here  the  nerve 
divides  into  an  upper  and  a  lower  branch.  The  upper  supplies  the 
anterior  part  of  the  deltoid  and  the  skin  over  it ;  the  lower  supplies 
the  back  part  of  the  deltoid,  and  gives  the  nerve  to  the  teres  minor,1 
upon  which  nerve  sometimes  a  little  gangliform  swelling  can  be 
seen :  it  enters  the  under-  aspect  of  the  middle  of  this  muscle. 
After  furnishing  these  muscular  branches,  the  nerve  turns  round 
the  posterior  border  of  the  deltoid,,  and  diverges  in  filaments  which 
supply  the  skin  over  the  back  of  this  muscle  and  over  the  long 
head  of  the  triceps. 

LATISSIMUS  This  broad,  flat  muscle  forms  the  posterior  mar- 

DORSI.  gin  of  the  axilla.     It  arises  from  the  external  lip 

of  the  crest  of  the  ilium,  from  an  aponeurosis  attached  to  the  spinous 
processes  of  the  six  lower  dorsal,  of  all  the  lumbar,  and  of  the  sacral 
vertebrae  and  their  supraspinous  ligament,  and  by  fleshy  digitations 
from  the  three  or  four  lower  ribs,  interdigitating  with  those  of  the 
external  oblique  ;  in  some  cases,  as  it  passes  over  the  inferior  angle 
of  the  scapula,  it  has  an  additional  origin  from  the  angle.  Its  fibres 
converge  from  this  large  origin,  and  the  muscle  is  inserted  into  the 
bottom  of  the  bicipital  groove  of  the  humerus  by  a  broad  flat  tendon, 
which  curves  round  the  lower  border  of  the  teres  major.  The 
axillary  vessels  and  nerves  lie  upon  the  tendon  close  to  its  in- 

1  This  branch  to  the  teres  minor  is  said  to  be  constant  in  all  mammalia  that 
have  been  examined  in  reference  to  this  point. 


MUSCLES   ATTACHED   TO   THE   SCAPULA.  323 

sertion.  Its  nerve  is  the  long  subscapular  branch  from  the  poste- 
rior cord  of  the  brachial  plexus,  and  it  enters  the  muscle  close  to  its 
anterior  border,  in  company  with  a  large  branch  of  the  subscapular 
artery. 

This  muscle  lies  behind,  and  to  the  inner  side 

of  the  latissimus  dorsi,  is  closely  connected  with 
it,  and  assists  in  forming  the  posterior  boundary  of  the  axilla.  It 
arises  from  the  oval  surface  on  the  dorsal  aspect  of  the  lower  angle 
of  the  scapula,  and  from  the  fibrous  septa  between  it  and  the  teres 
minor  and  infraspinatus,  and  is  inserted  by  a  broad  flat  tendon, 
about  two  inches  in  length,  behind  the  latissimus  dorsi,  into  the 
posterior  margin  of  the  bicipital  groove  of  the  humerus.  The 
tendon  extends  below  that  of  the  latissimus  dorsi,  and  a  bursa  or 
sac,  lubricated  with  serum,  intervenes  between  the  two  tendons. 
The  action  of  this  and  the  preceding  muscle  is  to  draw  the  humerus 
inwards  and  backwards.  Its  nerve  is  the  middle  subscapular,  and 
lies  along  the  dorsalis  scapulae  artery. 

This  muscle  arises  from  the  posterior  two-thirds 

of  the  subscapular  fossa  of  the  scapula,  with  the 
exception  of  the  angles,  neck,  and  the  posterior  border,  and  from 
the  intermuscular  septa  attached  to  the  bony  ridges.  Its  fibres 
converge  to  a  strong  tendon,  which  passes  under  the  axillary 
vessels  and  nerves,  over  the  inner  side  of  the  shoulder-joint,  and  is 
inserted  into  the  lesser  tuberosity  of  the  humerus,  and  into  the 
neck  of  the  humerus  for  an  inch  below  it.  The  tendon  of  the 
muscle  is  intimately  connected  with  the  capsular  ligament  of  the 
shoulder-joint,  and  between  the  base  of  the  coracoid  process  and 
the  tendon  is  a  bursa,  which  communicates  with  the  joint.  Its 
action  is  to  rotate  the  humerus  inwards,  and  when  the  arm  is 
raised  to  draw  it  to  the  side.  Its  nerves  come  from  the  upper  and 
middle  subscapular  nerves. 

SEEKATUS  This  muscle  covers  the  side  of  the  chest  like  a 

MAGNUS.  girth.     It    arises    from   the   front    of  the    outer 

surfaces  of  the  eight  upper  ribs  by  nine  slips  or  digitations,  the 
second  rib  having  two.  Its  fibres  converge,  and  are  inserted  into 
the  posterior  border  of  the  scapula  in  the  following  manner :  the 
first  two  digitations  are  attached  into  the  upper  angle  of  the 

Y   2 


324  DISSECTION   OF   THE    UPPER   ARM. 

scapula ;  the  third  and  fourth  digitations  along  nearly  the  whole 
length  of  the  posterior  border  ;  the  remainder  are  inserted  into  the 
inferior  angle.  Its  action  is  to  draw  the  scapula  forwards  ;  but  of 
this  more  hereafter.  It  is  supplied  by  the  following  nerve,  which 
is  seen  on  its  outer  surface. 

POSTERIOR  THO-  ^n^s  nerve  supplies  the  serratus  magnus  only. 
EACIC  OK  EXTEE-  It  comes  from  the  fifth  and  sixth  cervical  nerves  ; 
NAL  BESPIRATORY  and,  after  passing  through  the  scalenus  medius, 
NEBVE  OF  BELL.  rnng  1^^  the  axillary  vessels,  along  the  outer 
surface  of  the  serratus  magnus,  each  digitation  receiving  a  sepa- 
rate filament.1 


DISSECTION   OP   THE   UPPEK  ARM. 

SURFACE  In  front  of  the  upper  arm  may  be  distinguished 

MAEKING.  the  long  prominence  of  the  biceps  muscle,  and 

lower  down  at  the  bend  of  the  elbow  its  tendon  may  be  easily  felt. 
The  bend  of  the  elbow,  in  muscular  subjects,  presents  a  triangular 
depression,  with  its  boundaries  formed  on  the  inner  side  by  the 
pronator  teres,  and  on  the  outer  side  by  the  supinator  longus. 
Superficially  in  this  space  the  subcutaneous  veins  can  be  recog- 
nised, of  which  a  fuller  description  will  be  entered  into  later  on. 
On  the  inner  side  of  the  elbow,  the  internal  condyle  of  the  humerus 
is  very  prominent,  and  behind  this,  is  the  olecranon ;  between  these 
is  a  hollow  in  which  may  be  felt  the  ulnar  nerve.  The  olecranon 
is  situated  nearer  the  internal  than  the  external  condyle,  which  is 
visible  on  the  outer  side ;  below  this,  is  a  dimple  which  corresponds 
with  the  head  of  the  radius. 

Continue  the  incision  down  the  inner  side  of 

the  arm  as  far  as  two  inches  below  the  elbow,  and 

then  make  a  transverse  incision  from  the  inner  to  the  outer  side  of 

the  forearm.     Reflect  the  skin,  and  trace  out  the  cutaneous  nerves, 

and  the  numerous  veins  in  front  of  the  elbow. 


1  It  may  be  asked  why  this  nerve  is  called  the  external  respiratory.  It  was  so 
named  by  Sir  C.  Bell,  who  considered  the  serratus  magnus  as  the  external  respira- 
tory muscle,  co-operating  with  the  diaphragm  or  internal  respiratory  muscle. 


CUTANEOUS    NERVES    OF   THE    ARM. 


325 


CUTANEOUS 
NERVES. 


On  the  inner  side  of  the  arm  are  the  intercosto- 
humeral,  the  internal  cutaneous  branch  of  the 
musculo-spiral,  the  internal  cutaneous,  and  the  lesser  internal 
cutaneous  (nerve  of  Wrisberg)  nerves  ;  on  the  outer  side  are  the 
cutaneous  branches  of  the  circumflex,  the  external  cutaneous 

FIG.  79. 


1.  Acromial 

branches 

Vperfi 

2.  Clavicular    vica 

branches  J 


of    the    su- 
perficial cer- 
1  plexus. 


3.  Cutaneous    branches   of 

the  circumflex  nerve. 

4.  Branches  of  the  internal 

cutaneous  nerve. 


5.  External          cutaneous 

branch    of    the    mus- 
culo-spiral nerve. 

6.  Internal  cutaneous  nerve. 

7.  Its    posterior    cutaneous 

branch. 

8.  The  cutaneous  branch  of 

the  mnsculo-cutaneous 
nerve. 


DISTRIBUTION    OF   CUTANEOUS   NERVES    TO    THE    FRONT    OF    THE    SHOULDER 
AND   ARM. 

branches  of  the  musculo-spiral,  and  lower  down  is  the  musculo- 
cutaneous  nerve. 

The  filaments  of  the  intercosto-Jmmeral  nerves  (p.  313)  descend  along 
the  inner  and  posterior  part  of  the  arm  as  far  as  the  olecranon,  and 
communicate  with  the  internal  cutaneous  branch  of  the  musculo-spiral 
nerve. 

The  internal  cutaneous  nerve  perforates  the  fascia,  with  the  basilic 
vein  about  the  middle  of  the  arm,  and  divides  into  an  anterior  and  a 


326  CUTANEOUS  NERVES   OF  THE   ARM. 

posterior  branch  ;  the  anterior  passes  down  in  front  of  the  arm  (as  a 
rule  beneath  the  median  basilic  vein),  and  supplies  the  skin  as  far  as 
the  wrist,  communicating  with  a  cutaneous  branch  of  the  ulnar  nerve  ; 
the  posterior  winds  round  to  the  back  of  the  forearm  behind  the  internal 
condyle  as  far  as  the  wrist,  and  communicates  above  the  elbow  with 
the  nerve  of  Wrisberg,  and  above  the  wrist  with  the  dorsal  branch  of 
the  ulnar  nerve. 

The   lesser  internal  cutaneous   (nerve  of  Wrisberg)  perforates  the 

FIG.  80. 


Basilic  vein     .    .    .    . IK  I  lp — Cephalic  vein. 

Median  basilic  vein  .    .  -H/fSf-'  X^C^BL Median  cephalic  vein. 

Deep  median  vein    .    _  • 

Median  vein. 


SUPERFICIAL  VEINS  AND  NEKVES  AT  THE  END  OF  THE  LEFT  ELBOW. 

fascia  about  the  lower  third  of  the  arm,  and  supplies  the  skin  over  the 
internal  condyle  and  the  olecranon.  This  nerve,  as  it  lies  close  to  the 
axillary  vein,  communicates  with  the  first  or  second  intercosto-humeral 
nerve. 

The  internal  cutaneous  branch  of  the  rmisculo- spiral  nerve  pierces 
the  fascia,  and  supplies  the  skin  of  the  inner  and  posterior  aspect  of  the 
middle  of  the  arm  as  far  as  the  olecranon. 

The  c^ltaneous  branches  of  the  circ^^.mflex  nerve  pierce  the  fascia  over 


VEINS   IN   FRONT   OF   THE   ELBOW.  327 

the  insertion  of  the  deltoid,  and  supply  the  skin  of  the  upper  half  of  the 
arm  on  its  outer  side. 

The  external  cutaneous  branches  of  the  musculo- spiral  nerve  are  two 
in  number  :  the  upper  and  smaller  accompanies  the  cephalic  vein  in  the 
lower  half  of  the  arm  ;  the  lower  may  be  traced  down  the  outer  and 
back  part  of  the  forearm  nearly  as  far  as  the  wrist,  where  it  joins  the 
posterior  branch  of  the  musculo-cutaneous  nerve. 

On  the  outer  side  of  the  tendon  of  the  biceps,  the  cutaneous  branch 
of  the  musculo-cutaneous  nerve  perforates  the  fascia,  and  divides  into 
many  filaments,  which  supply  the  skin  of  the  outer  part  of  the  fore- 
arm. 

DISPOSITION  or  Attention  should  now  be  directed  to  the  dis- 

VKINS  IN  FKONT  OF  position  of  the  veins  in  front  of  the  elbow.  In 
THE  ELBOW.  cleaning  these  veins,  take  care  not  to  divide  the 

branches  of  the  internal  and  external  cutaneous  nerves  which  pass 
over  and  under  them. 

The  following  is  the  ordinary  -arrangement  of  the  superficial 
veins  at  the  bend  of  the  elbow  (fig.  80).  On  the  outer  side  is  the 
radial ;  on  the  inner  side  is  the  ulnar  vein,  formed  by  the  junction 
of  the  anterior  and  posterior  ulnar  cutaneous  veins  ;  in  the  centre 
is  the  median,  which  divides  into  two  branches,  the  external  of 
which,  uniting  with  the  radial  to  form  the  cephalic  vein,  is  called 
the  median  cephalic ;  the  internal,  uniting  with  the  ulnar  to 
form  the  basilic,  is  named  the  median  basilic.  Near  its  bifur- 
cation, the  median  vein  communicates  by  a  branch  (mediana  pro- 
funda)  with  the  deep  veins  which  accompany  the  arteries  of  the 
forearm. 

Trace  the  cephalic  vein  up  the  arm.  It  runs  along  the  outer 
border  of  the  biceps  to  the  groove  between  the  pectoralis  major 
and  the  deltoid,  and  dipping  down  between  these  two  muscles, 
terminates  in  the  axillary  vein  immediately  above  the  pectoralis 
minor. 

The  basilic  vein,  the  largest  of  the  veins  of  the  upper  arm, 
ascends  along  the  inner  side  of  the  arm  with  the  internal  cutaneous 
nerve.  Near  the  middle  of  the  arm,  it  perforates  the  fascia,  and 
empties  itself  either  into  the  internal  vena  comes  of  the  brachia. 
artery,  or  into  the  axillary  vein. 


328  MyscuLAR  FASCIA  OF  THE  ARM. 


RELATION  OF  ^ne  principal  branches  of  the  cutaneous  nerves 

THE  CUTANEOUS  pass  beneath  the  veins  :  that  is  to  say,  as  a  rule, 
NEKVES  AND  VEINS  the  internal  cutaneous  passes  behind  the  median 
basilic  vein,  and  the  external  cutaneous  behind 
the  median  cephalic  :  but  it  should  be  remembered  that  many 
small  filaments  cross  in  front  which  are  exposed  to  injury  in 
venesection. 

EELATION  OF  Since  the  median  basilic  vein  is  larger  than  the 

MEDIAN  BASILIC  median  cephalic,  and,  on  account  of  the  strong 
VEIN  TO  BKA-  fascia  beneath,  more  easily  compressible,  it  is 

usually  chosen  for  venesection;  its  position,  there- 
fore, in  reference  to  the  brachial  artery,  becomes  important.  The 
vein  is  only  separated  from  the  artery  by  the  semilunar  fascia, 
derived  from  the  tendon  of  the  biceps.  This  fascia  is  in  some 
subjects  remarkably  thin.  Sometimes  the  artery  lies  above  the 
fascia,  in  contact  with  the  vein.  In  choosing,  therefore,  this  vein 
for  venesection,  there  is  a  risk  of  wounding  the  artery  ;  hence  the 
practical  rule,  to  bleed  either  from  the  median  cephalic,  or  from 
the  median  basilic  above  the  situation  where  it  crosses  the  brachial 
artery. 

LYMPHATIC  Immediately  above  the  internal  condyle,  in  the 

GLANDS.  neighbourhood  of  the  basilic  vein,  we  find  one  or 

two  small  lymphatic  glands.  Others  may  be  found  higher  up  along 
the  inner  side  of  the  arm.  A  gland  is  occasionally  met  with  at  the 
bend  of  the  elbow  ;  but  never  below  this  joint.  These  little  glands 
are  the  first  which  are  liable  to  become  tender  and  enlarged  after 
a  poisoned  wound  of  the  hand. 

MUSCULAR  The  fascia  which  invests  the  muscles  of  the 

FASCIA  AND  ITS  upper  arm  is  a  continuation  of  the  fascia  of  the 
CONNECTIONS.  trunk  and  the  axilla.  This  membrane  varies  in 

density:  thus  it  is  thin  over  the  biceps,  stronger  on  the  inner  side 
of  the  arm,  to  protect  the  brachial  vessels  and  nerves,  and  strongest 
over  the  triceps.  At  the  upper  part  of  the  arm  it  is  connected 
with  the  coracoid  process  and  the  clavicle  ;  it  is  strengthened  at 
the  axilla  by  an  expansion  from  the  tendons  of  the  pectoralis  major 
and  latissimus  dorsi  ;  posteriorly,  it  is  attached  to  the  spine  of 
the  scapula.  The  fascia  surrounds  the  brachial  vessels  with  a 


THE    BICEPS.  329 

sheath,  and  furnishes  partitions  which  separate  the  muscles  from 
each  other.  Of  these  partitions,  the  most  marked  are,  the  external 
and  internal  intermuscular  septa,  which  divide  the  muscles  on  the 
anterior  from  those  on  the  posterior  surface  of  the  upper  arm. 
These  septa  are  attached  to  the  condyloid  ridges  of  the  humerus 
and  to  the  condyles.  The  internal  intermuscular  septum,  the 
stronger  of  the  two,  begins  at  the  insertion  of  the  teres  major,  and 
is  connected  with  tendinous  insertion  of  the  coraco-brachialis  ;  it 
separates  the  triceps  extensor  from  the  brachialis  anticus,  to  both 
of  which  it  affords  attachment  to  their  muscular  fibres.  It  is 
pierced  by  the  ulnar  nerve  and  the  inferior  profunda  and  anastomotic 
arteries.  The  external  intermuscular  septum  commences  from  the 
insertion  of  the  deltoid,  and  separates  the  brachialis  anticus,  the 
supinator  longus,  and  the  extensor  carpi  radiali&  longior  in  front, 
from  the  triceps  extensor  behind,  to  all  of  which  muscles  it  affords 
attachment.  It  is  pierced  by  the  musculo-spiral  nerve  and  the 
superior  profunda  artery. 

At  the  lower  part  of  the  upper  arm,  the  fascia  is  remarkably 
strong,  especially  where  it  covers  the  brachialis  anticus,  and  the 
brachial  vessels,  and  is  continued  over  the  muscles  on  the  inner 
side  of  the  forearm.  At  the  back  of  the  elbow,  the  fascia  is 
attached  to  the  tendon  of  the  triceps,  and  the  olecranon. 

Now  remove  the  fascia  corresponding  to  the 
incisions  through  the  skin,  in  order  to  see  the 
muscles  on  the  front  of  the  arm — namely,  the  biceps,  the  coraco- 
brachialis,  and  the  brachialis  anticus.  The  long  rounded  muscle  in 
front  is  the  biceps ;  the  muscle  attached  with  it  to  the  coracoid 
process  is  the  coraco-brachialis ;  and  the  broad  flat  muscle  covering 
the  lower  end  of  the  humerus  is  the  brachialis  anticus. 

The  biceps,  as  its  name  implies,  arises  by  two 
heads — a  long  and  a  short.  The  short  head  arises 
from  the  tip  of  the  coracoid  process  of  the  scapula,  by  a  thick,  flat 
tendon  in  common  with  a  slender  muscle  on  its  inner  side,  called 
the  coraco-brachialis.  The  long  head  arises  from  the  upper  border 
of  the  glenoid  fossa  of  the  scapula  and  the  glenoid  ligament,  by  a 
long,  rounded  tendon,  which,  traversing  the  shoulder-joint,  passes 
over  the  head  of  the  humerus ;  there  pierces  the  capsular  ligament, 


330  THE    BICEPS. 

and  descends  in  the  groove  between  the  two  tuberosities.  The 
tendon  is  retained  in  the  groove  by  a  fibrous  bridge  derived  from 
the  capsule  of  the  joint,  and  connected  with  the  tendon  of  the  pec- 
toralis  major.  Divide  this  bridge,  and  see  that  the  synovial  mem- 
brane of  the  joint  is  reflected  round  the  tendon,  and  accompanies  it 
for  about  two  inches  down  the  groove,  thus  forming  a  synovial  fold. 
The  object  of  this  is  to  facilitate  the  play  of  the  tendon,  and  to 
carry  little  arteries  (from  the  anterior  circumflex)  for  its  supply. 
The  two  heads  unite  about  the  middle  of  the  arm,  and  form  a  single 
muscle,  which  terminates  on  a  strong  flat  tendon  of  considerable 
length ;  this  dips  down  into  the  triangular  space  at  the  bend  of 
the  elbow,  and,  after  a  slight  twist  upon  itself,  is  inserted  into  the 
posterior  part  of  the  tubercle  of  the  radius.  The  anterior  part  of 
the  tubercle,  over  which  the  tendon  plays,  is  crusted  with  cartilage,, 
and  a  bursa  intervenes  to  diminish  friction.  The  most  internal 
fibres  of  the  muscle  are  inserted  into  a  strong  broad  aponeurosis, 
which  is  prolonged  from  the  inner  border  of  the  tendon  to  the 
fascia  on  the  inner  side  of  the  forearm.  This  aponeurosis,  called 
the  semilunar  fascia  of  the  biceps,  .protects  the  brachial  vessels  and 
the  median  nerve  at  the  bend  of  the  elbow. 

The  action  of  the  biceps  is  twofold.  1.  It  is  a  flexor  of  the 
forearm.  2.  It  is  a  powerful  supinator  of  the  forearm,  in  conse- 
quence of  its  insertion  into  the  posterior  part  of  the  tubercle  of  the 
radius.  Its  power  of  supination  is  greatest  when  the  forearm  is 
half  bent,  because  its  tendon  is  then  inserted  at  a  right  angle. 
Why  does  the  long  tendon  pass  through  the  shoulder-joint  ?  It 
acts  like  a  strap,  and  confines  the  head  of  the  hunierus  in  its  proper 
centre  of  motion.1  But  for  this  tendon,  the  head  of  the  bone,  when 
the  deltoid  acts,  would  be  pulled  directly  upwards  and  strike  against 
the  under  surface  of  the  acromion.  When  the  tendon  is  ruptured, 
or  dislocated  from  its  groove,  a  man  can  move  his  arm  backwards 
and  forwards,  but  he  cannot  raise  the  smallest  weight.2  The 

1  Another  action  of  the  long  tendon  of  the  triceps  would  seem  to  be  that  of  an 
internal  rotator  of  the  humerus  when  that  bone  is  rotated  externally.   The  marked 
prominence  of  the  internal  tuberosity  and  the  groove  on  its  outer  aspect  would 
favour  this  view. 

2  See  a  preparation  in  the  Museum  of  St.  Bartholomew's  Hospital. 


BKACHIALIS   ANTICUS.  331 

biceps  is  supplied  with  blood  by  a  branch  from  the  brachial,  which 
runs  into  the  middle  of  its  inner  side,  and  divides  into  ascending 
and  descending  branches.  Its  nerve  comes  from  the  musculo- 
cutaneous. 

COEACO-  This  thin  muscle  is  situated  at  the  upper  part 

BKACHIALIS.  of  the  arm,  and  runs  parallel  to  the  inner  border 

of  the  short  head  of  the  biceps.  It  arises  by  fleshy  fibres  from  the 
point  of  the  coracoid  process,  in  common  with  the  short  head  of 
the  biceps,  and  from  a  fibrous  septum  which  lies  between  them. 
The  muscle  descends  backwards  and  outwards,  and  terminates  on 
a  flat  tendon,  which  is  inserted  into  the  inner  side  of  the  middle  of 
the  humerus,  between  the  brachialis  anticus  and  the  inner  head  of 
the  triceps.  Its  action  is  to  draw  the  humerus  forwards  and  in- 
wards— e.g.  in  bringing  the  gun  up  to  the  shoulder.  It  is  supplied 
by  a  branch  from  the  musculo-cutaneous  nerve  which  pierces  it. 

Concerning  the  coraco-brachialis,  remember  :  1 .  That  the  mus- 
culo-cutaneous nerve  runs  through  it;  2.  That  its  inner  fleshy 
border  is  the  guide  to  the  axillary  artery  in  the  last  part  of  its 
course ;  3.  That  the  brachial  artery  lies  upon  its  flat  tendon  of  in- 
sertion, and  can  here  be  effectually  compressed  by  the  finger  or  the 
tourniquet. 

The  coraco-brachialis  and  biceps  are  covered  at  their  upper  part 
by  the  deltoid  and  pectoralis  major.  The  head  of  the  humerus 
rolls  beneath  the  coraco-brachialis  and  short  origin  of  the  biceps  ; 
and  a  large  bursa  is  interposed  between  these  muscles  and  the 
tendon  of  the  subscapularis,  which  covers  the  head  of  the  bone. 

BRACHIALIS  This  broad  muscle  covers  the  lower  half  of  the 

ANTICCS.  humerus,  and  is  partially  concealed  by  the  biceps. 

Between  the  two  muscles  is  the  musculo-cutaneous  nerve,  which 
supplies  them  both. 

It  arises  from  the  humerus  by  a  fleshy  digitation  on  either  side 
of  the  tendon  of  the  deltoid  ;  from  the  lower  half  of  the  front  and 
inner  surfaces  of  the  bone,  and  from  the  intermuscular  septa.  The 
muscle,  becoming  thicker  and  broader,  covers  the  front  of  the  cap- 
sule of  the  elbow-joint,  to  which  it  is  more  or  less  attached,  and 
terminates  on  a  tendon,  which  is  inserted  in  a  'pointed  manner 
into  the  anterior  surface  of  the  coronoid  process  of  the  ulna.  Its 


332  BRACHIAL   AETERY. 

action  is  to  bend  the  forearm.  Its  nerves  come  from  the  musculo- 
cutaneous',  and  it  usually  receives  in  addition  a  small  branch  from 
the  musculo-spiral. 

Now  examine  the  course  and  relations  of  the  brachial  vessels 
and  nerves. 

COURSE  AND  BE-  Th®  brachial  artery — the  continuation  of  the 
IATIONS  or  THE  axillary — takes  its  name  at  the  lower  border  of 
BRACHIAL  ARTERY.  foe  teres  majOr.  It  runs  down  the  anterior  and 
the  inner  side  of  the  arm,  along  the  inner  border  of  the  coraco- 
brachialis  and  biceps,  to  about  an  inch  below  the  elbow,  where  it 
divides,  near  the  coronoid  process  of  the  ulna,  into  the  radial  and 
ulnar  arteries. 

Thus  its  direction  corresponds  with  a  line  drawn  from  the 
deepest  part  of  the  axilla  to  the  middle  point  between  the  condyles 
of  the  humerus. 

In  the  upper  part  of  its  course  it  lies  on  the  long  and  inner 
heads  of  the  triceps  (from  the  long  head  it  is  separated  by  the 
musculo-spiral  nerve  and  superior  profunda  artery)  ;  in  the  middle, 
it  lies  on  the  tendon  of  the  coraco-brachialis ;  in  the  lower  part,  on 

the  brachialis  anticus. 

• 

In  front  of  the  artery  are  the  internal  cutaneous  nerve,  the 
median  basilic  and  basilic  veins ;  the  median  nerve,  which  crosses 
obliquely  over  the  artery,  being  on  its  outer  side  near  the  axilla,  and 
on  its  inner  side  near  the  elbow ;  and  lastly,  the  artery  is  more 
or  less  overlapped,  in  the  first  part  of  its  course,  by  the  coraco- 
brachialis,  lower  down  by  the  fleshy  belly  of  the  biceps ;  the  inner 
borders  of  these  muscles,  in  their  respective  situations,  being  the 
best  guides  to  the  artery. 

On  the  outer  side  of  the  artery  are,  the  median  nerve,  the  coraco- 
brachialis,  and  biceps. 

On  the  inner  side  are,  at  first,  the  ulnar  nerve,  the  internal 
cutaneous  nerves ;  and,  below,  the  median  nerve. 

The  artery  is  accompanied  by  two  veins  (vence  comites)  and  the 
median  nerve,  all  of  which  are  invested  in  a  common  sheath  of 
fascia. 

The  ulnar  nerve  runs  along  the  inner  side  of  the  artery  as  far 
as  the  middle  of  the  arm.  Below  this  point,  the  nerve  leaves  the 


BRANCHES  OF  THE  BRACHIAL  ARTERY.  333 

artery,  and  passes  through  the  internal  intermuscular  septum  to  get 
behind  the  internal  condyle. 

About  the  middle  of  the  humerus,  the  artery  lies  for  nearly  two 
inches  on  the  tendon  of  the  coraco-brachialis,  and  is  so  close  to  the 
bone  that  it  can  be  effectually  compressed,  provided  the  pressure 
be  made  in  the  proper  direction — namely,  outwards.  Here,  too,  it 
is  crossed  by  the  median  nerve. 

At  the  bend  of  the  elbow  the  artery  is  crossed  by  the  seinilunar 
fascia  from  the  biceps.  It  enters  a  triangular  space,  bounded  by 
the  pronator  radii  teres  internally,  and  by  the  supinator  radii  longus 
externally.  It  sinks  into  this  space,  with  the  tendon  of  the  biceps 
to  its  outer  side,  and  the  median  nerve  to  its  inner ;  all  three  rest 
upon  the  brachialis  anticus!  To  compress  the  artery  here,  pressure 
should  be  made  directly  backwards.  Opposite  the  coronoid  process 
of  the  ulna  it  divides  into  the  radial  and  ulnar  arteries. 

Two  veins,  of  which  the  internal  is  the  larger,  lie  in  close  con- 
tact with  the  brachial  artery,  and  communicate  at  frequent  intervals 
by  transverse  branches.  Near  the  axilla  they  join  and  form  the 
axillary  vein. 

BRANCHES  OF  The  brachial  artery  gives  off  four  branches,  all 

BKACHIAL  ARTERY,  from  its  inner  side  :  namely,  the  superior  profunda, 
the  inferior  profunda,  the  nutrient  artery,  and  the  anastomotica 
magna.  It  also  distributes  muscular  branches  to  the  coraco- 
brachialis  and  biceps,  which  are  given  off  from  its  outer  side. 

a.  The  profunda  superior  arises  from  the  inner  and  back  part  of 
brachial  artery,  immediately  below  the  tendon  of  the  teres  major.1  It 
winds  round  the  back  of  the  humerus,  between  the  outer  and  inner 
heads  of  the  triceps,  accompanied  by  the  musculo-spiral  nerve,  and,  a 
little  above  the  middle  of  the  arm,  divides  into  two  branches,  which 
run  for  some  distance  on  either  side  of  the  nerve.  One  of  these  runs  in 
the  substance  of  the  triceps  muscle,  with  the  nerve  to  the  anconeus,  as 
far  as  the  olecranon,  and  anastomoses  with  the  posterior  ulnar  recur- 
rent, the  interosseous  recurrent,  and  anastomotica  magna  arteries  :  the 
other  branch  accompanies  the  musculo-spiral  nerve  to  the  outer  side  of 

1  If  the  profunda  be  not  in  its  usual  place,  look  for  it  above  the  tendon  of  the 
latissimus  dorsi,  where  it  will  probably  be  given  off  from  a  common  trunk  with  the 
posterior  circumflex. 


334 


BRANCHES    OF   THE    BRACHIAL    ARTERY. 


the  arm,  where  it  perforates  the  external  intermuscular  septum.  It 
then  descends  deep  in  the  interval  between  the  brachialis  anticus  and 
supinator  radii  longus,  and  terminates  in  numerous  ramifications,  some 
of  which  pass  in  front  of  the  external  condyle,  others  behind  it,  to 
inosculate  with  the  radial  and  interosseous  recurrent  arteries. 

Fia.  81. 


Superior  profunda  .    .    .    , 


Interosseous  recurrent  .    .. 


Radial  recurrent    .    .    .    . 


Posterior  interosseons     .    . 


— Inferior  profunda. 


Anastomotica  magna. 

Anterior  ulnar  recurrent. 
Posterior  ulnar  recurrent. 

Common  interosseous. 
Anterior  interosseous. 


PLAN    OF    THE    CHIEF  BRANCHES    OF    THE    BRACHIAL   ARTERY   AND    THE    ARTERIAL 
INOSCULATIONS   ABOUT    THE    RIGHT    ELBOW-JOINT. 

Before  its  division,  the  superior  profunda  sends  several  branches  to 
the  deltoid,  coraco-brachialis,  and  the  triceps,  some  of  which  inosculate 
with  the  circumflex.  These  assist  in  establishing  a  collateral  cir- 
culation when  the  brachial  artery  is  ligatured  above  the  origin  of  the 
profunda. 

b.  The  profunda  inferior  arises  from  the  brachial,  opposite  to  the 


BRANCHES  OF  THE  BRACHIAL  ARTERY.  335 

insertion  of  the  coraco-brachialis,  or  sometimes  by  a  common  trunk 
with  the  superior  profuiida.  It  runs  with  the  ulnar  nerve  on  the  inner 
head  of  the  triceps  (which  it  supplies),  passes  through  the  internal 
intermuscular  septum,  and  then  descends  to  the  interval  between  the 
internal  condyle  and  the  olecranon,  inosculating  with  the  posterior  ulnar 
recurrent  and  anastomotica  magna  arteries.  It  also  sends  a  small 
branch  down  in  front  of  the  internal  condyle  to  anastomose  with  the 
anterior  ulnar  recurrent. 

c.  The  nutrient  artery  of  the  humerus  arises  sometimes  from  the 
brachial,  sometimes  from  the  inferior  profunda.     It  pierces  the  tendon 
of  the  coraco-brachialis,  runs  obliquely  downwards  through  the  bone, 
and   in   the  medullary   canal   divides   into  ascending  and  descending 
branches,    which   anastomose   with  the  nutrient   vessels  of   the  bone 
derived  from  the  periosteum. 

d.  The  anastomotica  magna  arises  from  the  inner  side  of  the  brachial, 
about  two  inches  above  the  elbow,  runs  tortuously  inwards  transversely 
across  the  brachialis  anticus,  and  divides  into  branches,  some  of  which 
pass  in  front  of  the  internal"  condyle,  anastomosing  with  the  anterior 
ulnar  recurrent   artery ;    another   passes  behind  the  internal  condyle 
by  piercing  the  intenial  intermuscular-  septum,  and  anastomoses  with 
the  inferior  profunda  and  posterior  ulnar  recurrent  arteries  ;  and  one 
branch  forms  an  arch,  above  the  olecranon  fossa,  with  the  superior 
profunda. 

e.  Numerous  mitscular  branches  arise  from  the  outer  side  of  the 
brachial  artery  :  one  of  these,  the  bicipital,  more  constant  than  the 
rest,  supplies  the  biceps  ;  another  runs  transversely  beneath  the  coraco- 
brachialis  and  biceps,  over  the  insertion  of  the  deltoid,  supplying  this 
muscle  and  the  brachialis  anticus- 

The  two  veins  which  accompany  the  brachial 
artery  are  continuations  of  the  deep  radial  and 
ulnar  veins.  The  internal  is  usually  the  larger,  and  generally 
receives  the  veins  corresponding  to  the  principal  branches  of  the 
artery.  In  their  course  they  are  connected  at  intervals  by  trans- 
verse branches  either  in  front  of,  or  behind  the  artery.  Near  the 
subscapularis,  the  vena  comes  externa  crosses  obliquely  in  front  of 
the  axillary  artery  to  join  the  vena  comes  interna,  which  then  takes 
the  name  of  axillary. 

Now  trace  the  great  nerves  of  the  upper  arm,  which  proceed 
from  the  brachial  plexus  near  the  tendon  of  the  subscapularis  : 


336  NERVES    OF   THE    UPPER    ARM. 

namely,  the  median,  the  musculo-cutaneous,  the  ulnar,  and  the 
musculo-spiral  nerves. 

The  median  nerve,  so  called  from  the  course  it 
takes  along  the  front  of  the  arm  and  the  forearm, 
arises  by  two  roots,  which  converge  in  front  of  the  axillary  artery 
(p.  321).  The  external  root  is  derived  from  the  outer  cord,  in  com- 
mon with  the  musculo-cutaneous  ;  the  internal  from  the  inner  cord, 
in  common  with  the  ulnar  and  internal  cutaneous.  In  its  course 
down  the  arm,  the  nerve  is  situated  at  first  on  the  outer  side  of 
the  brachial  artery,  between  it  and  the  coraco-brachialis ;  about 
the  middle  of  the  arm  the  nerve  crosses  obliquely  over  (in  some 
cases  under)  the  vessel,  so  that  at  the  bend  of  the  elbow  it  is  found 
on  the  inner  side  of  the  artery,  lying  upon  the  brachialis  anticus, 
and  covered  by  the  semilunar  fascia  from  the  biceps.1 

As  a  summary  of  the  distribution  of  the  median  nerve,  we  may 
say  that  it  supplies  the  two  pronators  and  all  the  flexors  of  the 
forearm  (except  the  flexor  carpi  ulnaris  and  the  ulnar  half  of  the 

1  I  have  observed  the  following  varieties  relating  to  the  median  nerve,  and  its 
course  in  regard  to  the  artery. 

a.  The  roots  may  be  increased  in  number  by  one  on  either  side  of  the  artery  ; 
or  the  internal  root  may  be  deficient. 

b.  They  may  vary  in  their  position  with  regard  to  the  artery  :  both  may  be 
situated  behind  the  vessel ;  or  one  behind,  and  the  other  in  front  of  it. 

c.  The  nerve,  formed  in  the  usual  manner,  may  be  joined  lower  down  by  a  large 
branch  from  the  external  cutaneous ;  such  a  case  presents  a  junction  of  two  large 
nerves  in  front  of  the  brachial  artery,  in  the  middle  of  the  arm. 

d.  The  nerve  in  many  cases  crosses  under,  instead  of  over  the  artery. 

e.  The  nerve  sometimes  runs  parallel  and  external  to  the  artery ;  or  it  may 
run  parallel  to,  and  in  front  of,  the  artery. 

In  one  hundred  arms  the  relative  position  of  the  nerve  to  the  artery  in  its 
course  down  the  arm  was  as  follows  : — 

In  72,  the  nerve  took  the  ordinary  course. 
„  20,  the  nerve  crossed  obliquely  under  the  artery. 
,,     5,  the  nerve  ran  parallel  and  superficial  to  the  artery. 
,,     3,  the  nerve  ran  parallel  and  external  to  the  artery. 

These  varieties  of  the  median  nerve  are  of  practical  importance,  for  this 
reason  :  whenever  in  the  operation  of  tying  the  brachial  artery,  we  do  not  find  the 
nerve  in  its  normal  position,  we  may  expect  to  find  some  irregular  distribution  of 
the  arteries — e.g.  a  high  division  of  the  brachial,  or  even,  which  I  have  often  seen, 
a  '  vas  aberrans  '  coming  from  the  upper  part  of  the  brachial,  and  joining  either 
the  radial  or  ulnar  arteries. 


MUSCULO-CUTANEOUS   AND    ULNAE  NERVES.  337 

flexor  profundus  digitorum)  ;  the  muscles  of  the  ball  of  the  thumb, 
the  two  radial  lumbricales,  both  sides  of  the  thumb,  fore  and  middle 
fingers,  and  the  radial  side  of  the  ring  finger,  on  their  palmar 
aspect. 

MORCULO-CUTA-  This  nerve  (often  called  the  external  cutaneous 

NEOUS  NERVE.  or  perforans  Casserii)  arises  in  common  with  the 

external  root  of  the  median,  from  the  external  cord  of  the  brachial 
plexus  behind  the  pectoralis  minor,  and  is  situated  on  the  outer 
side  of  the  axillary  artery.  It  perforates  the  coraco-brachialis 
obliquely,  and  then  runs  down  between  the  biceps  and  the  bra- 
chialis  anticus  to  the  outer  side  of  the  arm.  A  little  above  the 
elbow-joint,  between  the  tendon  of  the  biceps  and  the  supinator 
radii  longus,  the  nerve  pierces  the  deep  fascia  and  becomes  subcu- 
taneous ;  then  passing  under  the  median  cephalic  vein,  it  divides 
into  an  anterior  and  a  posterior  branch,  for  the  supply  of  the  inte- 
guments of  the  forearm. 

The  musculo-cutaneous  nerve,  in  the  upper  part  of  its  course, 
sends  branches  to  the  coraco-brachialis  and  the  short  head  of  the 
b'iceps,  and,  as  it  descends  between  the  biceps  and  the  brachialis 
anticus,  it  supplies  both.  Consequently,  if  the  nerve  were  divided 
in  the  axilla,  the  result  would  be  inability  to  bend  the  arm.1  This 
nerve  also  sends  small  filaments  to  supply  the  elbow-joint. 

This  nerve  arises  from  the  inner  cord  of  the 
ULXAB  NERVE.  .  .  . 

brachial  plexus,  m  common  with  the  internal  cuta- 
neous and  the  inner  head  of  the  median.  It  descends  along  the 
inner  side  of  the  brachial  artery,  as  far  as  the  insertion  of  the 
coraco-brachialis.  The  nerve  then  diverges  from  the  artery,  run- 
ning obliquely  over  the  inner  head  of  the  triceps,  perforates  the 
internal  intermuscular  septum,  and  runs  with  the  inferior  profunda 
artery,  behind  the  internal  condyle. 

1  In  some  instances  the  musculo-cutaneous  nerve  descends  on  the  inner  side 
of  the  coraco-brachialis  without  perforating  the  muscle  ;  in  these  cases  it  often 
sends  a  larger  branch  than  usual  to  the  median  nerve. 

The  trunk  of  the  musculo-cutaneous  nerve  may  come  from  the  median  at  any 
point  between  the  axilla  and  the  middle  of  the  arm.  In  some  subjects  the  nerve 
is  absent ;  all  its  branches  are  then  supplied  by  the  median,  which  is  larger  than 
usual.  Such  anomalies  are  easily  explained  by  the  fact  of  the  two  nerves  having 
a  common  origin. 

Z 


338  MUSCULO-SPIRAL   NERVE. 

The  distribution  of  the  nerve  is  to  the  elbow-joint,  to  the  flexor 
carpi  ulnaris,  to  half  the  flexor  profundus  digitornm,  to  all  the  in- 
terosseous  muscles  of  the  hand,  to  both  sides  of  the  little  finger,  to 
the  ulnar  side  of  the  ring  finger,  on  their  dorsal  and  palmar  aspects, 
to  the  muscles  of  the  ball  of  the  little  finger,  to  the  wrist-joint,  to 
the  two  ulnar  lumbricales,  and,  lastly,  to  the  adductor  pollicis,  and 
the  inner  head  of  the  flexor  brevis  pollicis. 

Previous  to  the  examination  of  the  musculo-spiral  nerve,  we 
should  examine  the  great  muscle  which  occupies  the  whole  of  the 
posterior  part  of  the  humerus — viz.  the  triceps  extensor  cubiti. 

TRICEPS  EXTEN-         This  muscle  has  three  distinct  origins,  named, 
SOB  CUBITI.  from  their  position,  the  external,  the  internal,  and 

the  middle  or  long  heads  (p".  318).  The  middle  or  long  head  arises  by 
a  flat  tendon  from  the  inferior  border  of  the  scapula,  close  to  the 
glenoid  cavity,  and  in  connection  with  the  glenoid  and  capsular 
ligaments.  The  external  head  arises  from  the  humerus,  beginning 
in  a  pointed  form  immediately  below  the  insertion  of  the  teres 
minor,  from  the  posterior  surface  between  this  and  the  musculo- 
spiral  groove,  and  from  the  external  intermuscular  septum.  The 
internal  head  arises  from  the  humerus  below  the  insertion  of  the 
teres  major,  from  the  posterior  surface  of  the  bone  below  the  mus- 
culo-spiral groove,  and  from  the  internal  intermuscular  septum. 
The  three  heads  unite,  near  the  middle  of  the  arm,  to  form  a  single 
fleshy  mass,  which  covers  the  posterior  part  of  the  elbow-joint,  and 
is  inserted  by  a  thick  tendon  into  the  summit  and  sides  of  the  ole- 
cranon.  There  is  a  bursa  between  the  tendon  and  the  olecranon, 
which  is  sometimes  multilocular.  Each  head  is  supplied  by  a 
separate  branch  from  the  musculo-spiral  nerve.1 

MUSCULO-SPIBAL         This,  the  largest  of  the  brachial  nerves,  arises, 
NEKVE.  in  common  with  the  circumflex,  from  the  posterior 

cord  of  the  axillary  plexus  (p.  320).  It  descends  at  first  behind  the 
axillary  artery,  and  then  behind  the  brachial  artery ;  it  subsequently 
winds  obliquely  round  the  posterior  part  of  the  humerus,  between 
the  external  and  internal  heads  of  the  triceps,  in  company  with  the 
superior  profunda  artery.  About  the  lower  third  of  the  outer  side 

1  The  subanconcus,  a  small  muscle  situated  beneath  the  triceps,  will  be 
described  later  on. 


DISSECTION   OF   THE   FRONT   OF  THE   FOREARM.  339 

of  the  arm,  the  nerve  perforates  the  external  intermuscular  septum, 
and  then  runs  deeply  embedded  between  the  brachialis  anticus  and 
the  supinator  radii  longus. 

The  nerve  gives  off  branches  on  the  inner  side  of  the  humerus, 
to  the  inner  and  long  heads  of  the  triceps,  and  the  internal  cuta- 
neous branch. ;  on  the  back  of  the  humerus,  to  the  external  head  of 
the  triceps  and  the  anconeus ;  on  the  outer  side  of  the  humerus, 
to  the  supinator  radii  longus.  the  extensor  carpi  radialis  longior, 
and  the  brachialis  anticus  (usually)  ;  lastly,  after  perforating  the 
septum,  it  gives  off  the  upper  and  lower  external  cutaneous 
branches. 

A  little  above  the  elbow-joint  the  nerve  divides  into  its  two 
principal  branches — the  radial,  which  accompanies  the  radial  artery 
along  the  forearm,  and  the  posterior  interosseous,  which  perforates 
the  supinator  brevis,  and  supplies  the  muscles  on  the  back  of  the 
forearm. 

To  sum  up  the  muscular  distribution  of  this  nerve,  we  may  say 
that  it  supplies  all  the  extensors  of  the  forearm,  wrist,  thumb,  and 
fingers ;  and  all  the  supinators  except  one — namely,  the  biceps 
(supplied  by  the  musculo-cutaneous  nerve). 


DISSECTION   OF  THE   FRONT   OF   THE   FOREARM. 

SURFACE  The  front  of  the  forearm  presents,  at  the  bend 

MARKING.  of  the  elbow,  a  triangular  depression,  from  which 

there  extends  down  to  the  wrist  a  groove  which  corresponds  to  the 
radial  artery ;  on  the  inner  side  is  another  groove,  increasing  in 
depth  towards  the  wrist,  indicating  the  course  of  the  ulnar  artery. 
The  head  of  the  radius  can  be  easily  felt  on  the  outer  side,  below 
the  external  condyle  of  the  humerus,  and  in  the  lower  third  the 
bone  becomes  again  defined,  terminating  below  in  the  styloid  process, 
beyond  which  is  the  prominence  of  the  tubercle  of  the  scaphoid. 
The  border  of  the  ulna  can  be  felt  on  the  inner  side  of  the  forearm, 
in  the  lower  half,  and  it  ends  at  the  wrist  in  an  ill-defined  styloid 
process,  which  does  not  descend  as  low  as  the  corresponding  pro- 
cess of  the  radius.  The  lower  part  of  the  forearm  presents,  an  inch 

z  2 


340     CUTANEOUS  VEINS  AND  NERVES  OF  THE  FOREARM. 

beyond  the  wrist-joint,  a  transverse  furrow,  which  corresponds 
with  the  border  of  the  annular  ligament. 

Prolong  the  incision  down  to  the  wrist,  and,  at 

DISSECTION.  .  .  °    . 

its  termination,  make  another  transversely.     Re- 
flect the  skin,  and  dissect  the  subcutaneous  veins  and  nerves. 

CUTANEOUS  On  the  inner  side   is  the  anterior  ulnar  vein, 

VEINS.  which  commences  on  the  front  of  the  wrist,  and 

is  then  continued  upwards  on  the  inner  side  of  the  forearm  as  far 
as  the  elbow,  where  it  is  joined  by  the  posterior  ulnar  vein  to  form 
the  common  ulnar  vein.  This  vein  communicates  with  the  median 
vein  by  numerous  branches  (p.  326). 

The  veins  on  the  back  of  the  hand  commence  at  the  extremi- 
ties of  the  fingers,  run  up  between  the  knuckles,  and  unite  on  the 
back  of  the  hand,  forming  an  arch  with  its  concavity  upwards. 
The  posterior  ulnar  vein  arises  from  this  arch  by  a  branch  (vena 
salvatella)  situated  over  the  fourth  interosseous  space,  and  runs  up 
on  the  back  of  the  forearm,  towards  the  inner  condyle,  to  join  the 
anterior  ulnar  vein. 

The  radial  vein,  situated  on  the  outer  side  of  the  forearm,  com- 
mences on  the  back  of  the  hand  from  the  venous  arch,  runs  up  the 
radial  side  of  the  front  of.  the  forearm  to  the  elbow,  where,  after 
receiving  the  median  cephalic,  it  becomes  the  cephalic  vein. 

Running  up  in  front  of  the  middle  of  the  forearm  is  the  median 
vein  ;  it  communicates  in  the.  forearm  with  the  radial  and  ante- 
rior ulnar  veins,  and  near  the  bend  of  the  elbow  it  is  joined  by  a 
deep  branch — mediana  profunda — after  which  it  divides  into  two 
branches,  an  outer  or  median  cephalic,  which  joins  the  cephalic, 
and  an  inner  or  median  basilic,  which  joins  the  basilic  (fig.  80). 

CUTANEOUS  On  the  radial  side  of  the  forearm,  as  low  down 

NEBVES.  as  the  wrist,  are  found  the  terminal  filaments  of 

the  anterior  branch  of  the  musculo-cutaneous  nerve,  which,  about 
the  middle  of  the  forearm,  sends  a  posterior  branch  backwards  to 
supply  the  posterior  and  lower  part  of  the  forearm  as  low  as  the 
wrist,  communicating  with  the  radial  and  external  cutaneous 
branch  of  the  musculo-spiral.  At  the  lower  part  of  the  front 
of  the  forearm,  one  or  more  of  these  filaments  are  situated  over 
the  radial  artery,  and  one  branch  passes  to  the  palm  to  supply 


DEEP    FASCIA    OF   THE    FOREARM.  341 

the  skin  over  the  muscles  of  the  ball  of  the  thumb ;  it  commu- 
nicates with  the  palmar  branch  of  the  median  and  with  the  radial 
nerve. 

In  front  of  the  upper  part  of  the  forearm  are  some  filaments  of 
the  external  cutaneous  branch  of  the  musculo-spiral  nerve  ;  on  the 
outer  and  back  part  of  the  forearm,  near  the  elbow,  the  lower 
external  cutaneous  branch  of  the  musculo-spiral  runs  down  as  far 
as  the  wrist  to  supply  the  skin. 

At  the  lower  third  of  the  radial  side  of  the  forearm,  the  radial 
nerve  becomes  superficial,  and  turns  over  the  radius  to  supply  the 
back  of  the  hand  and  fingers. 

On  the  ulnar  side  the  anterior  division  of  the  internal  cuta- 
neous nerve  descends  as  far  as  the  wrist ;  its  posterior  branch 
passing  to  the  back  of  the  forearm  to  supply  it  as  far  as  the  middle. 
Near  the  styloid  process  of  the  ulna,  the  dorsal  branch  of  the  ulnar 
nerve  perforates  the  fascia  to  reach  the  back  of  the  hand. 

DEEP  FASCIA  OP  The  muscles  of  the  forearm  are  enveloped  by  a 

THE  FOKEAEM.  dense  shining  aponeurosis,  continuous  with  that 

of  the  arm.  Its  thickness  increases  towards  the  wrist,  that 
the  tendons,  in  this  situation,  may  be  kept  in  their  position.  It 
is  composed  of  fibres  which  cross  each  other  obliquely,  and  is 
attached,  above,  to  the  condyles  of  the  humerus  and  olecranon ; 
internally,  to  the  ridge  on  the  posterior  part  of  the  ulna.  At  the 
back  of  the  wrist,  it  forms  the  posterior  annular  ligament,  and  in 
front,  it  is  continuous  with  the  anterior  annular  ligament.  Above, 
the  fascia  is  strengthened  by  fibres  from  the  tendons  of  the  biceps 
and  brachialis  anticus.  The  aponeurotic  expansion  from  the  inner 
edge  of  the  tendon  of  the  biceps  is  exceedingly  strong.  It  braces 
the  muscles  on  the  inner  side  of  the  forearm,  and  interlaces  at 
right  angles  with  the  fibres  of  the  fascia  attached  to  the  internal 
condyle.  The  under  surface  of  the  fascia  gives  origin  to  the  mus- 
cular fibres  in  the  upper  part  of  the  forearm,  and  furnishes  septa 
which  separate  the  muscles,  and  form  surfaces  for  their  origin. 
The  fascia  is  perforated  at  various  parts  for  the  passage  of  the 
cutaneous  vessels  and  nerves  of  the  forearm. 

Remove  the  fascia  from  the  muscles  by  incisions 
corresponding   to    those  for  reflecting  the    skin  ; 


342  MUSCLES  OF  THE  FOREARM. 

taking  care  of  the  cutaneous  branches  of  the  median  and  ulnar 
nerves  close  to  the  wrist. 

TRIANGLE  AT  At  the  bend  of  the  elbow  is  a  triangular  space, 

THE  ELBOW.  with  its  base  towards  the  humerus  ;  on  the  inner 

side  this  space  is  bounded  by  the  pronator  teres  ;  on  the  outer,  by 
the  supinator  radii  longus.  In  it  are  the  following  objects  which 
must  be  carefully  dissected: — 1.  In  the  centre  is  the  brachial 
artery  (with  its  companion  veins)  dividing  into  the  radial  as  its 
outer,  and  into  the  ulnar  as  its  inner  branch ;  2,  on  the  outer  side 
of  the  artery  is  the  tendon  of  the  biceps ;  3,  on  the  inner  side  is 
the  median  nerve  ;  4,  the  musculo-spiral  nerve  on  the  outer  side 
is  partly  concealed  by  the  supinator  longus ;  5,  the  radial  recurrent 
artery  >  6,  the  anterior  ulnar  recurrent ;  7,  the  common  interos- 
seous  branch  of  the  ulnar  artery  ;  8,  the  vena  mediana  profunda. 

MUSCLES  OF  The  muscles  of  the  forearm  are  arranged  in  two 

THE  FOBEARM.  groups  :  one,  consisting  of  supinators  and  exten- 

sors, is  attached  to  the  outer  condyloid  ridge  and  condyle;  the 
other,  consisting  of  pronator  and  flexors,  is  attached  to  the  inner 
condyle.  The  inner  group  should  be  examined  first.  They  arise 
by  a  common  tendon,  and  are  arranged  in  the  following  order : 
pronator  teres ;  flexor  carpi  radialis  ;  palmaris  longus  ;  flexor  sub- 
limis  digitorum,  and  flexor  carpi  ulnaris. 

PRONATOR  This  muscle  forms  the  inner  boundary  of  the 

RADII  TERES.  triangular  space  at  the  elbow.     It  arises  by  two 

heads  ;  one,  from  the  anterior  surface  of  the  internal  condyle,  from 
the  common  tendon,  from  the  fascia  of  the  forearm,  and  from  the 
septum  between  it  and  the  flexor  carpi  radialis ;  the  other,  by  a 
small  tendinous  origin  from  the  inner  border  of  the  coronoid  pro- 
cess of  the  ulna.  From  these  two  origins,  between  which  the 
median  nerve  passes,  the  muscle  proceeds  obliquely  downwards 
and  outwards  across  the  forearm,  and  is  inserted  by  a  flat  tendon 
into  a  rough  surface  on  the  outer  and  back  part  of  the  middle 
third  of  the  radius.  In  amputating  the  forearm,  it  is  very  desir- 
able to  save  the  insertion  of  this  muscle,  that  the  stump  may  have 
a  pronator.  its  nerve  comes  from  the  median. 

FLEXOR  CARPI  This  muscle,  situated  on  the  ulnar  side  of  the 

EADIALIS.  preceding  muscle,  arises  by  the  common  tendon 


MUSCLES  OF  THE  FOREARM. 


343 


from  the  internal  condyle,  from  the  intermuscular  septa,  and  from 
the  fascia  of  the  forearm.  The  fleshy  fibres  terminate  a  little 
above  the  middle  of  the  forearm,  in  a  flat  tendon,  which  runs  in  a 


FIG.  82. 


1.  Biceps. 

2.  Brachialis  anticus. 
3    Sapinator  longus. 

4.  Pronator  radii  teies. 

5.  Flexor  carpi  radialis. 

6.  Palmaris  longus. 

7.  Flexor  carpi  ulnaris. 


8.  Flexor  sublimis  digitorum. 

9.  Flexor  longus  pollicis. 

10.  Extensor  ossis  metacarpi  and 

the  primi  internodii  pollicis. 

11.  Triceps. 

12.  Radial  artery. 

13.  Ulnar  artery. 


DIAGRAM    OF    THE    MUSCLES    OF    THE    FRONT    OF    THE    FOREABM. 

separate  sheath  outside  the  anterior  annular  ligament  of  the  wrist, 
passes  through  a  groove  in  the  os  trapezium,  bridged  over  by  fibrous 
tissue  and  lined  by  a  synovial  membrane,  and  is  inserted  into  the 
base  of  the  metacarpal  bone  of  the  index  finger.  The  outer  border 


344  MUSCLES  OF  THE  FOEEARM. 

of  its  tendon  is  the  guide  to  the  radial  artery  in  the  lower  half  of 
the  forearm.  Its  nerve  comes  from  the  median.1 

PALMARIS  This   slender  muscle  arises  from  the   common 

LONGUS.  tendon    at  the  internal   condyle,  from  the  inter- 

rnuscular  septa,  and  from  the  fascia  of  the  forearm.  About  the 
middle  of  the  forearm  it  terminates  in  a  flat  tendon,  which  de- 
scends along  the  middle  of  the  forearm  to  the  wrist,  lying  upon 
the  flexor  sublimis  digitorum ;  it  then  passes  over  the  anterior 
annular  ligament,  and  is  continued  into  the  palmar  fascia.  This 
muscle  is  a  tensor  of  the  palmar  fascia.2  Its  nerve  comes  from  the 
median. 

FLEXOK  CARPI  This  muscle  arises  by  two  heads  :  one  from  the 

ULNARIS.  internal    condyle,  the    common  tendon,  and   the 

intermuscular  septum ;  the  other  from  the  inner  edge  of  the 
olecranon  :  these  two  origins  form  an  arch,  under  which  the  ulnar 
nerve  and  the  posterior  ulnar  recurrent  artery  pass.  It  also  arises 
from  the  upper  two-thirds  of  the  posterior  edge  of  the  ulna, 
through  the  medium  of  the  aponeurosis,  which  is  common  to  this 
muscle,  the  flexor  profundus  digitorum,  and  the  extensor  carpi 
ulnaris.  The  tendon  appears  on  the  radial  side  of  the  muscle,  about 
the  lower  third  of  the  forearm,  and  receives  fleshy  fibres  on  its  ulnar 
side  as  low  as  the  wrist.  It  is  inserted  into  the  pisiform  bone, 
and  thence  by  a  strong  tendon  into  the  unciform  and  the  base  of 
the  fifth  metacarpal  bone.  Its  nerve  comes  from  the  ulnar. 

The  tendon  of  the  flexor  carpi  ulnaris  is  the  guide  to  the  ulnar 
artery,  which  lies  close  to  its  radial  side,  and  is  overlapped  by  it. 
As  it  passes  over  the  annular  ligament,  the  tendon  furnishes  a 
fibrous  expansion  to  protect  the  ulnar  artery  and  nerve. 

FLEXOR  SUBLI-  This  muscle  has  three  distinct  origins,  and  is 

MIS  DIGITORUM.         situated  beneath  those   previously  mentioned,  so 

1  A  muscle  is  not  infrequently  found  beneath  this  muscle,  called  by  Mr. 
Wood  the  flexor  carpi  radialis  brevis,  or  profundus.  It  arises  from  the  front  of  the 
radius  above  the  pronator  quadratus,  and  is  inserted  into  the  base  of  the  meta- 
carpal bone  of  the  middle  finger.  (Journ.  of  Anat.  and  Phys.,  p.  55,  Nov.  1866.) 

'*  The  palmaris  longus  is  absent  in  about  one  out  of  ten  subjects.  The  situa- 
tion of  its  muscular  portion  is  subject  to  variety  ;  sometimes  occupying  the  middle, 
sometimes  the  lower  third  of  the  forearm.  The  tendon  is  in  some  instances  wholly 
inserted  into  the  anterior  annular  ligament. 


MUSCLES   OF   THE   FOREARM.  345 

that,  in  order  to  expose  it  fully,  the  preceding  muscles  should  be 
reflected,  by  cutting  them  through  the  middle,  and  turning  the 
ends  upwards  and  downwards.  The  longer  origin  takes  place  from 
the  internal  condyle,  from  the  internal  lateral  ligament,  the  com- 
mon tendon,  and  the  intermuscular  septa  ;  the  second  origin  takes 
place  from  the  coronoid  process  of  the  ulna  above  the  pronator 
teres ;  the  third  origin,  by  tendinous  and  fleshy  fibres  from  the 
oblique  ridge  on  the  front  of  the  radius,  extending  from  the 
tubercle  to  about  an  inch  below  the  insertion  of  the  pronator  teres. 
This,  called  its  radial  origin,  is  partly  concealed  by  the  pronator 
teres.  The  muscle,  thus  formed,  passes  down  the  middle  of  the 
forearm,  and  divides  into  four  distinct  muscular  slips  :  from  these, 
four  tendons  arise,  which  pass  beneath  the  annular  ligament, 
arranged  in  two  pairs  ;  the  tendons  of  the  middle  and  ring  fingers 
being  placed  over  those  of  the  fore  and  little  fingers.  The  tendons 
pass  through  the  palm  to  the  fingers,  where  they  diverge  and  split 
to  allow  the  passage  of  the  deep  flexor  tendons,  and  are  inserted 
into  the  sides  of  the  second  phalanges  where  they  will  be  subse- 
quently traced.  Its  action  is,  therefore,  to  bend  the  second  joint 
of  the  fingers. 

The  muscles  described  as  arising  from  the  internal  condyle  are 
all  supplied  by  the  median  nerve,  except  the  flexor  carpi  ulnaris, 
which  is  supplied  by  the  ulnar. 

Having  finished  the  superficial  muscles  on  the  inner  side  of 
the  forearm,  notice  one  of  those  on  the  outer  side,  named  supi- 
nator  radii  longus,  before  tracing  the  vessels  and  nerves  of  the 
forearm. 

SUPINATOB  This  muscle  forms  the  external  boundary  of  the 

RADII  LONGUS.  triangular  spac"e  at  the  bend  of  the  elbow.  It 
arises  by  fleshy  fibres  from  the  upper  two-thirds  of  the  external 
condyloid  ridge  of  the  humerus,  commencing  a  little  below  the 
insertion  of  the  deltoid,  and  from  the  external  intermuscular 
septum.  The  muscular  fibres  terminate  about  the  middle  of  the 
forearm  in  a  flat  tend.cn,  which  is  inserted  into  the  outer  side  of 
the  base  of  the  styloid  process  of  the  radius.  The  inner  border  of 
the  muscle  is  the  guide  to  the  radial  artery  which  lies  between  this 
muscle  and  the  flexor  carpi  radialis.  It  supinates  the  hand,  but 


346  RADIAL    ARTERY. 

acts  much  more  powerfully  as  a  flexor  of  the  forearm.    It  is  supplied 
by  the  musculo-spiral  nerve. 

The  radial  artery,  the  smaller  division  of  the 
brachial,  runs  down  the  radial  side  of  the  forearm 
to  the  wrist,  where  it  turns  over  the  external  lateral  ligament  of 
the  carpus,  beneath  the  extensor  tendons  of  the  thumb,  and  sinks 
into  the  angle  between  the  first  and  second  metacarpal  bones  to 
form  the  deep  palmar  arch.  Thus,  its  course  corresponds  with  a 
line  drawn  from  the  middle  of  the  bend  of  the  elbow  to  the  front 
of  the  styloid  process  of  the  radius. 

In  the  upper  third  of  the  forearm,  the  artery  lies  deep  between 
the  pronator  teres  on  the  inner  and  the  supinator  longus  on  the 
outer  side  ;  the  fleshy  border  of  the  latter  overlaps  it  in  muscular 
subjects.  In  the  lower  two-thirds  of  the  forearm  the  artery  is 
more  superficial,  and  is  placed  between  the  tendons  of  the  supi- 
nator longus  on  the  outer  and  the  flexor  carpi  radialis  on  the  inner 
side.  In  its  course,  it  lies  successively  on  the  following  : — first, 
upon  the  tendon  of  the  biceps  ;  secondly,  upon  the  supinator  radii 
brevis  ;  thirdly,  upon  the  insertion  of  the  pronator  teres ;  fourthly, 
upon  the  radial  origin  of  the  flexor  sublimis  ;  fifthly,  upon  the 
flexor  longus  pollicis  ;  sixthly,  upon  the  pronator  quadratus,  and 
lastly,  upon  the  lower  end  of  the  radius.  The  artery  then  turns 
round  the  outer  side  of  the  wrist-joint,  lying  upon  the  external 
lateral  ligament,  and  covered  by  the  tendons  of  the  extensores  ossi 
metacarpi,  and  primi  internodii  pollicis,  some  cutaneous  veins  and 
branches  of  the  radial  nerve  ;  next,  it  lies  upon  the  trapezium  ;  it 
is  then  crossed  by  the  extensor  secundi  internodii  pollicis  ;  and, 
lastly,  passing  between  the  two  heads  of  the  first  dorsal  interosseous 
muscle,  it  enters  the  palm  to  form  the  deep  palmar  arch.  It  is 
accompanied  by  two  veins,  which  communicate  at  frequent  inter- 
vals, ard  join  the  venae  comites  of  the  brachial  artery  at  the  bend 
of  the  elbow. 

In  the  middle  third  of  its  course  the  artery  is  accompanied  by 
the  radial  nerve  (a  branch  of  the  musculo-spiral),  which  lies  to  its 
outer  side.  Below  this  point,  the  nerve  leaves  the  artery,  and 
passes,  under  the  tendon  of  the  supinator  longus,  to  the  back  of 
the  hand. 


BRANCHES  OF  THE  RADIAL  ARTERY.  347 

Thus,  in  the  situation  where  the  pulse  is  usually  felt,  the  radial 
nerve  no  longer  accompanies  the  artery ;  nevertheless,  the  vessel 
is  accompanied  by  a  branch  of  the  musculo-cutaneous  (or  external 
cutaneous),  which  lies  superficially  to  it. 

The  radial  artery  sends  off  in  the  forearm  the  following  branches, 
besides  offsets,  which  supply  the  muscles  on  the  outer  side  of  the 
forearm — 

a.  The  radial  recurrent  is  given  off  just  below  the  elbow  ;  it  ascends 
upon  the  supinator  brevis,  between  the  supinator  longus  and  the  bra- 
chialis  anticus,  to  supply  the  long  and  short  supinators  and  the  two 
radial  extensors.     It  runs  up  with  the  musculo- spiral  nerve,  and  forms 
a  delicate  inosculation  with  the  superior  profunda  (p.  333). 

b.  The  muscular  branches  which  are  given  off  to  the  muscles  on  the 
outer  side  of  the  forearm. 

c.  The  arteria  superficialis  voice,  arises  from  the  radial,  about,  half 
an  inch,  or  more,  above  the  lower  end  of  the  radius  :  it  runs  over  the 
anterior  annular  ligament,  above,  or  through,  the  origin  of  the  muscles 
of  the  ball  of  the  thumb,  into  the  palm  of  the  hand,  where  it  sometimes 
inosculates  with  the  superficial  branch  of  the  ulnar,  and  completes  the 
superficial  palmar  arch.1 

d.  The  anterior  carpal  artery  is  a  small  branch  of  the  radial,  which 
arises  close  to  the  lower  border  of  the  pronator  quadratus,  and  then  runs 
beneath  the  tendons,  and  supplies  the  anterior  surface  of  the  synovial 
membrane  and  bones  of  the  carpus,  anastomosing  with  the  anterior 
interosseous,  the  anterior  carpal  branch  of  the  ulnar,  and  the  recurrent 
carpal  branch  of  the  deep  palmar  arch. 

At  the  wrist  it  gives  off — 

e.  The  posterior  carpal  artery,  which   runs   beneath  the   extensor 
tendons,'  and  joins  the  corresponding  branch  of  the  ulnar  to  form  an 
arch ;  it  also  anastomoses  with  the  anterior  interosseous  artery  on  the 
back  of  the  wrist. 

The  radial  nerve,  a  branch  of  the  musculo-spiral, 
is  given  off  above  the  bend  of  the  elbow,  deep 

1  There  is  great  variety  in  the  size  and  origin  of  the  superficialis  volse  ;  some- 
times it  is  very  large,  arises  higher  than  usual,  and  runs  to  the  wrist  parallel  with 
the  radial ;  sometimes  it  is  very  small,  terminating  in  the  muscles  of  the  thumb  ; 
or  it  may  be  absent. 


348  ULNAR    ARTERY. 

between  the  supinator  radii  longus  and  brachialis  anticus ;  it 
descends  on  the  outer  side  of  the  radial  artery,  covered  by  the 
supinator  radii  longus.  In  the  upper  third  of  the  forearm,  the 
nerve  is  at  some  distance  from  the  artery  ;  in  the  middle  third,  it 
approaches  nearer  to  it,  lying  to  its  outer  side  j  but  in  the  lower 
third,  the  nerve  leaves  the  artery,  passes  underneath  the  tendon  of 
the  supinator  longus,  perforates  the  deep  fascia  on  the  outer  side 
of  the  forearm,  and  becomes  subcutaneous.  It  then  divides  into 
two  branches :  an  outer,  the  smaller,  which  supplies  the  skin  of 
the  ball  of  the  thumb,  and  communicates  with  the  anterior  branch 
of  the  musculo-cutaneous  nerve ;  and  an  inner,  which  generally 
supplies  both  sides  of  the  dorsal  aspects  of  the  thumb,  of  the  index 
and  middle  fingers,  and  of  the  radial  side  of  the  ring  finger. 

This  artery,  the  larger  of  the  two  divisions  of 
the  brachia],  comes  off  below  the  elbow,  runs 
obliquely  inwards  along  the  ulnar  side  of  the  forearm  to  the  wrist, 
passes  over  the  annular  ligament  near  the  pisiform  bone,  and,  enter- 
ing the  palm,  forms  the  superficial  palmar  arch,  by  inosculating 
with  the  superficialis  volas. 

In  the  upper  half  of  its  course  the  artery  describes  a  gentle 
curve  with  the  concavity  towards  the  radius,  and  lies  deep  beneath 
the  superficial  layer  of  muscles,  namely,  the  pronator  teres,  flexor 
carpi  radialis,  palmaris  longus,  and  flexor  sublimis  digitorum.  It 
is  also  crossed  in  its  upper  part  by  the  median  nerve.  In  the 
lower  part  of  its  course  it  comes  nearer  the  surface,  and  descends 
between  the  flexor  sublimis  and  flexor  carpi  ulnaris,  of  which  the 
tendon  partially  overlaps  it  at  the  wrist.  The  artery  lies  for  a 
short  distance  on  the  brachialis  anticus  ;  in  the  remainder  of  its 
course  it  lies  on  the  flexor  profundus  digitorum. 

The  ulnar  nerve  is  at  first  separated  from  the  artery  by  a  con- 
siderable interval :  about  the  middle  of  the  forearm  it  joins  the 
artery,  and  accompanies  it  in  the  rest  of  its  course,  lying  close  to 
its  inner  side.  Both  pass  over  the  anterior  annular  ligament  of 
the  carpus,  lying  close  to  the  pisiform  bone, — the  nerve  being 
nearer  to  the  ulnar  side  and  a  little  behind  the  artery.  A  strong 
expansion  from  the  tendon  of  the  flexor  carpi  ulnaris  protects  them 
in  this  exposed  situation. 


BRANCHES  OF  THE  ULNAR  ARTERY.  349 

Observe  that  the  ulnar  artery,  in  the  lower  third  of  its  course, 
lies  under  the  radial  border  of  the  tendon  of  the  flexor  carpi 
ulnaris,  which  is  the  surgical  guide  to  the  vessel.  The  artery  is 
accompanied  by  two  veins,  which  join  the  venas  comites  of  the 
brachial. 

The  ulnar  artery  gives  off  the  following  branches  in  the  fore- 
arm : — 

a.  The  anterior  and  posterior  ulnar  recurrent  arteries  arise  imme- 
diately below  the  elbow-joint, — sometimes  by  a  common  trunk.     The 
anterior  passes  upwards  between  the  brachialis  anticus  and  the  pronator 
teres,    and   inosculates  with  the  inferior  profunda   and   anastomotica 
magna.     The  posterior,  the  larger,  ascends  between  the  flexor  sublimis 
and  the  flexor  profundus  digitorum,  to  the  space  between  the  internal 
condyle  and  the  olecranon  :  it  then  passes  up  between  the  two  heads  of 
the  flexor  carpi  ulnaris,  where  it  inosculates  with  the  inferior  profunda, 
the  anastomotica  magna,  and,  above  the  olecranon,  with  the  posterior 
interosseous  recurrent  (p.  333). 

b.  The  common  interosseovis  artery  is  about  half  an  inch  long.     It 
arises  from  the  ulnar,  just  below  the  tubercle  of  the  radius,  and  soon 
divides  into  the  anterior  and  posterior  interosseous,  which  we  shall 
examine  presently. 

c.  The  'muscular  branches  which  supply  the  muscles  on  the  ulnar 
side  of  the  forearm. 

d.  The  carpal  branches  are  given  off  just  above  the  pisiform  bone  : 
the  posterior  carpal  runs  beneath  the  tendon  of  the  flexor  carpi  ulnaris 
and  the  extensor  tendons,  and  forms,  with  the  corresponding  branch  of 
the  radial  artery,  an  arch,  from  which  are  usually  given  off  the  second 
and  third  dorsal  interosseous  arteries  :  these  anastomose  with  the  per- 
forating arteries.     The  anterior  carpal  runs  in  front  of  the  carpus, 
beneath  the  flexor  tendons,  supplies  the  synovial  membrane  and  the 
ligaments,  and  anastomoses  with  the  anterior  carpal  from  the  radial. 

This  nerve  runs  behind  the  internal    condvle, 
ULNAK  NEKVE.        ,  .    .  „    .       a  "  . 

between  two  origins  of  the  flexor  carpi   ulnaris. 

In  its  course  down  the  ulnar  side  of  the  upper  part  of  the  forearm, 
the  nerve  is  still  covered  by  this  muscle,  and  lies  upon  the  flexor 
profundus  digitorum.  About  the  middle  of  the  forearm,  the  nerve 
joins  the  ulnar  artery,  and  runs  along  its  inner  side  over  the 
anterior  annular  ligament  into  the  palm. 


350  ULNAR  AND  MEDIAN  NERVES. 

The  ulnar  nerve  gives  off  the  following  branches  : — 

a.  The  articular  branches  to  the  joint  are  given  off  to  it,  immediately 
behind  the  elbow. 

b.  The  muscular  branches  are  distributed  to  the  flexor  carpi  ulnaris 
and  the  ulnar  half  of  the  flexor  profundus  digitorum,  and  are  given  off 
from  the  ulnar  a  short  distance  below  the  elbow. 

c.  A  cutaneoiis  branch  is  given  off  about  the  middle  of  the  forearm, 
one  filament  of  which,  called  the  palmar  ctitaneous  branch,  accompanies 
the  ulnar  artery  to  the  palm,  and  communicates  with  branches  from  the 
median  nerve. 

d.  The  dorsal  cutaneous  branch,  of  considerable  size,  is  given  off  from 
the  ulnar  about  two  inches  above  the  styloid  process  of  the  ulna  to  pass 
to  the  back  of  the  hand.     It  crosses  under  the  tendon  of  the  flexor 
carpi  ulnaris,  pierces  the  deep  fascia,  and,  immediately  below  the  styloid 
process  of  the  ulna,  appears  on  the  back  of  the  hand,  where  it  divides 
into  branches  which  supply  the  back  of  the  little  finger,  and  half  the 
ring  :  here  also  it  sends  a  branch  which  communicates  with  the  corre- 
sponding branch  of  the  radial  nerve. 

e.  Articular  branches  are  also  distributed  to  the  wrist-joint. 

This  nerve,  at  the  bend  of  the  elbow,  lies  on 
the  inner  side  of  the  brachial  artery  and  beneath 
the  bicipital  fascia.  It  then  passes  between  the  two  heads  of 
origin  of  the  pronator  teres,  and  descends  along  the  middle  of  the 
forearm,  between  the  flexor  sublimis  and  the  flexor  profundus 
digitorum.  At  the  lower  part  of  the  forearm,  it  becomes  more 
superficial,  lying  above  the  wrist  between  the  outer  tendon  of 
the  flexor  sublimis  and  the  inner  border  of  the  tendon  of  the 
flexor  carpi  radialis ;  beneath,  or  to  the  ulnar  side  of  the  palmaris 
longus,  and  having  in  front  of  it  the  skin  and  deep  fascia  ;  it 
then  enters  the  palm  beneath  the  anterior  annular  ligament,  and 
divides  into  five  branches  for  the  supply  of  the  thumb,  both  sides 
of  the  fore  and  middle  fingers,  and  the  radial  side  of  the  ring 
finger. 

Immediately  below  the  elbow,  the  median  nerve  sends  off: — 

a.  The  musctdar  branches  to  the  pronator  teres,  and  to  all  the  flexor 
muscles  of  the  forearm,  except  the  flexor  carpi  ulnaris  and  the  ulnar 
half  of  the  flexor  profundus,  which  are  supplied  by  the  ulnar  nerve. 


DEEP  MUSCLES  OF  THE  FOREARM.  351 

6.  The  anterior  interosseous  nerve,  also  a  branch  of  the  median,  runs 
with  the  anterior  interosseous  artery  on  the  interosseous  membrane, 
lying  on  its  radial  side,  between  the  flexor  longus  pollicis  and  flexor 
profundus  digitorum  :  it  supplies  both  these  muscles  and  the  proiiator 
quadratus. 

c.  The  palmar  cutaneoiis  branch  is  given  off  from  the  median  before 
it  passes  beneath  the  annular  ligament.  This  branch  passes  over  the 
ligament,  and  divides  into  numerous  filaments  to  supply  the  skin  of  the 
palm  and  the  ball  of  the  thumb,  communicating  with  the  cutaneous 
palmar  branches  of  the  ulnar,  the  external  cutaneous,  and  the  radial 
nerves. 

Now  reflect  the  superficial  layer  of  muscles,  to 
see  those  more  deeply  seated.     Preserve  the  prin- 
cipal vessels  and  nerves. 

The  deep-seated  muscles  are,  on  the  ulnar  side,  the  flexor  digi- 
torum profundus  ;  and,  on  the  radial  side,  the  flexor  longus  pollicis ; 
beneath  both,  near  the  wrist,  lies  a  transverse  muscle,  the  pronator 
quadratus.  On  the  interosseous  membrane,  between  the  first  two 
named  muscles,  run  the  anterior  interosseous  artery  and  nerve. 

FLEXOK  PRO-  This  is  the  thickest  muscle  of  the  forearm.     It 

FTJNDUS  DIGITO-  arises  from  the  upper  two-thirds  of  the  anterior 
EUMg  surface  of  the  ulna,  surrounding  the  insertion  of 

the  brachialis  anticus  above,  from  the  same  extent  of  its  internal 
surface,  from  the  aponeurosis  attached  to  the  posterior  edge  of  the 
ulna,  and  from  the  ulnar  two-thirds  of  the  interosseous  membrane. 
About  the  middle  of  the  forearm  the  muscle  is  inserted  into  four 
flat  tendons,  of  which  only  that  which  goes  to  the  index  finger  is 
separate  from  the  others  above  the  wrist.  These  tendons  lie  upon 
the  same  plane,  and  pass  beneath  the  annular  ligament,  under 
those  of  the  superficial  flexor,  into  the  palm,  where  they  diverge 
to  pass  to  their  respective  fingers.  On  the  first  phalanx  of  the 
fingers,  the  tendons  of  the  deep  flexor  perforate  those  of  the  super- 
ficial, and  are  inserted  into  the  bases  of  the  third  or  ungual  pha- 
langes. It  derives  its  nerves  from  the  interosseous  branch  of  the 
median  and  from  the  ulnar. 

FLEXOR  LONGUS         This  muscle  is  situated  on  the  front  surface  of 
POLLICIS.  the  radius,  outside  the  preceding.     It  arises  from 

the  front  surface  of  the  radius,  between  the  tubercle  and  the  oblique 


352  ANTERIOR  INTEROSSEOUS  ARTERY. 

ridge  above,  and  the  pronator  quadratus  below,  and  from  the  inter- 
osseous  membrane.1  Its  tendon,  which  begins  on  the  ulnar  side  of 
the  muscle,  proceeds  beneath  the  annular  ligament  to  the  base  of 
the  last  phalanx  of  the  thumb.  Its  nerve  comes  from  the  inter- 
osseous  branch  of  the  median. 

PRONATOR  This  square  muscle  arises  from  the  lower  fourth 

QUADRATUS.  of  the  ulna  and  from  a  strong  aponeurosis  which 

covers  its  anterior  surface  ;  its  fibres  pass,  some  transversely,  some 
obliquely  outwards,  and  are  inserted  into  the  lower  fourth  of  the 
anterior  surface  and  the  outer  border  of  the  radius.  It  pronates 
the  radius  on  the  ulna.  Its  nerve  proceeds  from  the  interosseous 
branch  of  the  median.  . 

ANTERIOR  Nearly   on    a  level  with    the  insertion  of  the 

INTEROSSEOUS  biceps,  the  ulnar  artery  gives  off  from  its  outer 

ARTERY.  g^e   ^he  common  interosseous,  which  runs    back- 

wards for  about  an  inch,  and  divides  into  the  anterior  and  posterior 
interosseous. 

The  anterior  interosseous  artery  runs  down  on  the  interosseous 
membrane,  lying  deeply  between  the  flexor  profundus  digitorum 
and  flexor  longus  pollicis.  At  the  upper  edge  of  the  pronator 
quadratus  it  divides  into  two  branches ;  one  of  which,  the  smaller, 
passes  beneath  the  muscle,  supplies  it  and  the  front  of  the  carpal 
bones,  communicating  with  the  anterior  carpal  arteries  from  the 
radial  and  ulnar ;  the  other,  the  more  important,  perforates  the 
interosseous  membrane,  and  helps  to  supply  the  muscles  on  the 
back  of  the  forearm . 

A  branch,  the  arteria  comes  nervi  mediani,  proceeds  from  the  anterior 
interosseous.  It  lies  in  close  contact  with  the  nerve,  sometimes  in  its 
very  centre  :  though  usually  of  small  size,  it  may  be  as  large  as  the 
ulnar  artery  itself,  and,  in  such  cases,  it  passes  under  the  annular  liga- 
ment with  the  nerve  to  join  the  palmar  arch.  This  is  interesting, 
because  it  helps  to  explain  the  recurrence  of  haemorrhage  from  a  wound 
in  the  palm,  even  after  the  radial  and  ulnar  arteries  have  been  tied. 

The  anterior  interosseous  artery  gives  off  branches  to  the  muscles  on 
each  side  ;  also  the  mitrient  arteries  which  enter  the  radius  and  ulna, 
near  the  centre  of  the  forearm,  to  supply  the  medullary  membrane  ; 
these  arteries  pass  upwards  towards  the  elbow. 

1  Sometimes  by  a  slip  from  the  coronoid  process. 


DISSECTION   OF  THE   PALM   OF  THE   HAND. 

ANTERIOR  IN-  ^his  nerve  is  a  branch  of  the  median  ;  it  gene- 

TEROSSEOUS  rally  runs  close  to  the  radial  side  of  the  artery, 

NEEVE-  and   supplies  the  flexor  longus  pollicis,  half  the 

flexor  profundus  digitorum,  and  the  pronator  quadratus. 


DISSECTION  OF  THE  PALM  OF  THE  HAND. 

SURFACE  On  the  ulnar  side  of  the  palm  of  the  hand  is 

MARKING.  a  round  long  eminence,  hypothenar,  which  corre- 

sponds with  the  muscles  of  the  ball  of  the  little  finger ;  and  on  the 
radial  side,  placed  obliquely  over  the  metacarpal  bone  of  the  thumb, 
is  another  eminence,  thenar,  which  is  caused  by  the  muscles  of  the 
ball  of  the  thumb.  Between  the  two  eminences,  at  the  wrist, 
is  a  slight  depression,  corresponding  'with  the  middle  of  the 
annular  ligament,  and  which  broadens  out  towards  the  fingers. 
The  palm  of  the  hand,  about  an  inch  from  the  clefts  of  the  fingers, 
presents  a  transverse  furrow,  which  corresponds  with  the  meta- 
carpo-phalangeal  articulations,  with  the  distal  limit  of  the  synovial 
sheaths  of  the  flexor  tendons,  with  the  divisions  of  the  palmar 
fascia  into  its  four  processes,  and  with  the  transverse  metacarpal 
ligament.  The  superficial  palmar  arch  may  be  indicated  by  a  line 
drawn  from  the  cleft  of  the  extended  thumb  across  the  palm  ;  the 
deep  palmar  arch  lies  half  an  inch  nearer  the  annular  ligament. 

Make  a  vertical  incision  along  the  centre  of  the 
palm,  and  a  transverse  one  along  the  bases  of  the 
fingers ;  from  this  transverse  cut  continue  vertical  incisions  along 
the  front  of  the  fingers,  and  reflect  the  skin ;  taking  care  not  to 
remove  a  small  cutaneous  muscle — the  palmaris  brevis — situated 
over  the  ball  of  the  little  finger,  and  also  two  small  cutaneous 
branches  of  the  median  and  ulnar  nerves,  which  are  found  in  the 
fat  of  the  palm. 

Observe  how  closely,  in  the  centre  of  the  palm,  the  skin  adheres 
to  the  palmar  fascia  beneath  it.  On  the  ball  of  the  little  finger 
and  the  distal  ends  of  the  metacarpal  bones,  the  subcutaneous 
structure  is  composed  of  a  dense  filamentous  tissue,  which  con- 
tains numerous  pellets  of  fat,  forming  an  elastic  pad.  A  similar 

A 'A 


354  PALMAR   FASCIA. 

padding  protects  the  palmar  surfaces  of  the  fingers.  These  cushions 
on  the  ends  of  the  fingers  defend  them  in  the  powerful  actions  of 
the  hand;  they  are  also  useful  in  subservience  to  the  nerves  of  touch. 

The  palm  is  supplied  with  nerves  by  three  small  branches — 
the  palmar  branch  of  the  median  passes  in  front  of  the  anterior 
annular  ligament  to  the  centre  of  the  palm ;  the  palmar  branch  of 
the  ulnar  supplies  the  inner  aspect  of  the  hand;  and  the  ante- 
rior branch  of  the  musculo-cutaneous  nerve  is  distributed  to  the 
skin  over  the  thenar  eminence.  The  terminal  branches  of  these 
cutaneous  nerves  communicate  with  each  other. 

PALMAEIS  This  small  cutaneous  muscle  is  situated  on  the 

BEEVIS.  inner  side  of  the  palm.     It  arises  from  the  inner 

edge  of  the  central  palmar  fascia  and  the  annular  ligament,  and  is 
inserted  into  the  skin  on  the  ulnar  border  of  the  palm.  Its  use  is 
to  support  the  pad  on  the  inner  edge  of  the  palm  :  it  acts  power- 
fully as  we  grasp;  it  raises  the  inner  edge  of  the  palm,  and  deepens 
the  hollow  of  it,  forming  the  so-called  '  cup  of  Diogenes.'  It  is 
supplied  by  the  ulnar  nerve. 

This  fascia  has  a  silvery  lustre,  and,  in  the 
centre  of  the  palm,  is  remarkably  dense  and 
strong.  It  is  divided  into  three  portions :  a  central,  by  far  the 
strongest ;  an  external,  covering  the  muscles  of  the  thumb ;  and 
an  internal,  covering  the  muscles  of  the  little  finger.  From  the 
deep  surface  of  the  fascia  two  septa  dip  down,  and  divide  the  palm 
into  three  separate  compartments ;  one  for  the  ball  of  the  thumb, 
a  second  for  that  of  the  little  finger,  and  a  third  for  the  centre  of 
the  palm. 

The  fascia  is  formed  by  a  prolongation  from  the  anterior  an- 
nular ligament.  It  is  also  strengthened  by  the  expanded  tendon 
of  the  palmaris  longus. 

The  central  portion  of  the  fascia  is  triangular,  with  the  apex 
at  the  wrist.  About  the  middle  of  the  palm  it  splits  into  four 
portions,  which  are  connected  by  transverse  tendinous  fibres, 
extending  completely  across  the  palm,  and  corresponding  pretty 
nearly  to  the  transverse  furrow  of  the  skin  in  this  situation. 

Examine  any  one  of  these  four  portions  of  the  fascia,  and  you 
will  find  that  it  splits  into  two  strips  which  embrace  the  corre- 


PALM   OF   THE   HAND.  355 

spending  flexor  tendons,  and  are  intimately  connected  with  the 
transverse  metacarpal  ligament.  The  effect  of  this  is  that  the 
flexor  tendons  of  each  finger  are  kept  in  place  in  the  palm,  by  a 
fibrous  ring.  Between  the  four  divisions  of  the  palmar  fascia  the 
digital  vessels  and  nerves  emerge,  and  descend  in  a  line  with  the 
clefts  between  the  fingers. 

In  the  hands  of  mechanics,  in  whom  the  palmar  fascia  is  usually 
very  strong,  we  find  that  slips  of  it  are  lost  in  the  skin  at  the  lower 
part  of  the  palm,  and  also  for  a  short  distance  along  the  sides  of 
the  fingers. 

The  chief  use  of  the  palmar  fascia  is,  to  protect  the  vessels  and 
nerves  from  pressure,  when  anything  is  grasped  in  the  hand.  It 
also  confines  the  flexor  tendons  in  their  proper  place. 

Beneath  the  interdigital  folds  of  the  skin,  there  are  aponeurotic 
fibres  to  strengthen  them,  constituting  what  are  called  the  trans- 
verse ligaments  of  the  fingers.  They  form  a  continuous  ligament 
across  the  lower  part  of  the  palm,  in  front  of  the  digital  vessels 
and  nerves. 

•  Cut  through  the  palmar  fascia  at  its  attachment 
to  the  anterior  annular  ligament,  and  reflect  it 
towards  the  fingers,  so  as  to  expose  the  vessels,  nerves,  and  tendons 
in  the  palm.  The  vessels  lie  above  the  nerves,  and  the  tendons 
still  deeper.  There  is  an  abundance  of  loose  connective  tissue  to 
allow  the  free  play  of  the  tendons.  When  suppuration  takes  place 
in  the  palm,  it  is  seated  in  this  tissue.  Reflect  for  a  moment 
what  mischief  is  likely  to  ensue.  The  pus  cannot  come  to  the 
surface  through  the  dense  palmar  fascia,  or  on  the  back  of  the 
hand ;  it  will,  therefore,  run  up  into  the  carpal  bursa  under  the 
annular  ligament,  and  make  its  way  deep  amongst  the  tendons  of 
the  forearm. 

SUPERFICIAL  The  ulnar  artery,  having  passed  over  the  annular 

PALMAK  AECH.  ligament,  near  the  pisiform  bone,  describes  a  curve 

across  the  upper  part  of  the  palm,  beneath  the  palmar  fascia,  to- 
wards the  thumb,  and,  gradually  diminishing  in  size,  inosculates 
with  the  superficialis  volse,  and  very  commonly  with  a  branch  from 
the  arteria  radialis  indicis,  to  form  the  superficial  palmar  arch. 
The  curve  of  the  arch  is  directed  towards  the  fingers,  its  greatest 

A  A  2 


356 


SUPERFICIAL   PALMAR   ARCH. 


convexity  descending  as  low  as  a  horizontal  line  drawn  across  the 
junction  of  the  upper  with  the  middle  third  of  the  palm. 

In  its  passage  over  the  annular  ligament,  the  artery  lies  in  the 
furrow,  between  the  pisiform  and  unciform  bones,  and  is  protected 


FIG.  83. 


Kadial  artery 


Superficialis  volae  . 

Arteria  magna 
pollicis  .... 

Radialis  indicia .    . 


Ulnar  artery. 


Ulnaris  profunda. 


DIAGRAM   OF   THE    SUPERFICIAL   AND   DEEP  PALMAR   ARCHES. 
1,  2,  3,  4.  Interosseous  branches. 

by  an  expansion  from  the  tendon  of  the  flexor  carpi  ulnaris  to  the 
palmaris  longus.  The  ulnar  nerve  lies  close  to  the  inner  side  of 
the  artery,  both  being  covered  by  the  palmaris  brevis.  In  the 
palm,  the  artery  rests  for  a  short  distance  upon  the  muscles  of  the 


ULNAR  NERVE  IN  THE  PALM.  357 

little  finger,  then  it  lies  upon  the  superficial  flexor  tendons  and  the 
divisions  of  the  ulnar  and  median  nerves,  and  is  covered  by  the 
palmar  fascia. 

Immediately  below  the  pisiform  bone,  the  ulnar  artery  gives  off 
the  ulnaris  profunda,  which  sinks  deeply  into  the  palm,  between 
the  origins  of  the  abductor  and  flexor  brevis  minimi  digiti,  to  form 
the  deep  palmar  arch,  by  joining  the  terminal  branch  of  the  radial 
artery.  It  is  accompanied  by  the  deep  branch  of  the  ulnar  nerve. 

From  the  concavity  of  the  arch  small  recurrent  branches  ascend  to 
the  carpus,  and  inosculate  with  the  other  carpal  branches  of  the  radial 
and  ulnar  arteries. 

Four  digital  arteries  arise  from  the  convexity  of  the  arch.  They 
supply  all  the  digits,  except  the  thumb  and  the  radial  side  of  the  index 
finger.  The  first  descends  over  the  muscles  on  the  inner  side  of  the 
palm,  to  the  ulnar  side  of  the  little  finger,  along  which  it  runs  to  the 
apex.  The  second,  third,  wad  fourth  descend  nearly  vertically  between 
the  tendons,  in  a  line  with  the  clefts  between  the  fingers,  and,  about 
half  an  inch  above  the  clefts,  each  divides  into  two  branches,  which 
proceed  along  the  opposite  sides  of  the  fingers  nearly  to  the  end  of  the 
last  phalanges,  where  they  unite  to  form  an  arch  with  the  convexity 
towards  the  end  of  the  finger  ;  from  this  arch  numerous  branches 
supply  the  papillae  at  the  tip  of  the  finger. 

In  the  palm  of  the  hand  the  digital  arteries,  before  they  divide, 
are  joined  by  branches  from  the  corresponding  palmar  interosseous 
arteries  (branches  of  the  deep  palmar  arch)  (fig.  83). 

The  digital  arteries  freely  communicate,  on  the  palmar  and 
dorsal  aspect  of  the  fingers,  by  transverse  branches,  which  supply 
the  joints  and  the  sheaths  of  the  tendons.  Near  the  ungual 
phalanx,  a  considerable  branch  passes  to  the  back  of  the  finger,  and 
forms  a  network  of  vessels  which  supply  the  matrix  of  the  nail. 

ULNAR  NEBVE  The  ulnar  nerve  passes  over  the  annular  liga- 

IN  THE  PALM.  ment  into  the  palm,  on  the  inner  side  of  the  ulnar 

artery,  and  a  little  behind  it.  It  lies  in  the  groove  between  the 
pisiform  and  unciform  bones,  so  that  it  is  perfectly  secure  from 
pressure.  Immediately  below  the  pisiform  bone,  the  nerve  divides 
into  a  superficial  and  a  deep  palmar  branch.  The  deep  branch 
supplies  the  muscles  forming  the  ball  of  the  little  finger,  and 


358          MUSCLES  OF  THE  BALL  OF  THE  THUMB. 

accompanies  the  ulnaris  profunda  artery  into  the  palm,  to  supply 
all  the  interosseous  muscles,  the  two  ulnar  lumbricales,  and  it  ends 
in  branches  which  are  distributed  to  the  first  dorsal  interosseous, 
the  adductor  pollicis,  and  the  inner  head  of  the  flexor  brevis  pollicis  : 
it  moreover  sends  filaments  which  ascend  to  supply  the  wrist-joint, 
and  others  which  descend  to  the  metacarpo-phalangeal  joints. 
The  superficial  branch  sends  filaments  to  the  palmaris  brevis,  to  the 
skin  on  the  inner  side  of  the  palm,  and  then  divides  into  two  digi- 
tal nerves,  one  for  the  supply  of  the  ulnar  side  of  the  little  finger, 
the  other  for  the  contiguous  sides  of  the  little  and  ring  fingers. 
This  branch  also  communicates  with  the  median  nerve  behind  the 
superficial  palmar  arch.  All  the  digital  branches  run  along  the 
sides  of  the  fingers  to  their  extremities  superficial  to  their  corre- 
sponding arteries. 

ANTEEIOB  AN-  This  exceedingly  strong  and  thick  ligament  con- 

KULAB  LIGAMENT  fines  the  flexor  tendons  of  the  fingers  and  thumb, 
OF  THE  CARPUS.  an(j  fastens  together  the  bones  of  the  carpus.  It  is 
attached,  externally,  to  the  tuberosity  of  the  scaphoid  and  the  ridge 
on  the  trapezium  ;  internally,  to  the  pisiform  and  unciform.  Its 
upper  border  is  continuous  with  the  aponeurosis  in  front  of  the 
wrist ;  its  lower  is  connected  with  the  palmar  fascia ;  its  anterior 
surface  receives  the  expanded  tendon  of  the  palmaris  longus,  and 
gives  origin  to  most  of  the  muscles  of  the  ball  of  the  thumb  and 
little  finger. 

Now  proceed  to  the  muscles  composing  the  ball  of  the  thumb 
and  the  little  finger.  The  dissection  of  them  requires  considerable 
care. 

MUSCLES  OF  The  great  strength  of  the  muscles  of  the  ball  of 

THE  BALL  OF  the  thumb  is  one  of  the  distinguishing  features  of 

THE  THUMB.  fae  numan  hand.     This  strength  is  necessary  in 

order  to  oppose  that  of  all  the  fingers.  In  addition  to  its  strength, 
the  thumb  enjoys  perfect  mobility.  It  has  no  less  than  eight 
muscles — namely,  an  abductor,  an  opponens,  two  flexors,  three 
extensors,  and  an  adductor. 

ABDUCTOB  This  is  the  most  superficial.     It  is  a  thin,  flat 

POLLICIS.  muscle,  and  arises  from  the  ridge  of  the  os  trape- 

zium and  the  annular  ligament.     It  passes  forwards  and  outwards, 


MUSCLES   OF  THE   BALL   OF  THE   LITTLE   FINGER.  359 

and  is  inserted  by  a  flat  tendon  into  the  radial  side  of  the  base  of 
the  first  phalanx  of  the  thumb.  Its  action  is  to  draw  the  thumb 
away  from  the  fingers.  Its  nerve  comes  from  the  median.  Reflect 
it  from  its  insertion  to  expose  the  following  : — 

OPPONENS  This  muscle  arises  from  the  front  of  the  os  tra- 

POLLICIS.  pezium  beneath  the  abductor,  and  from  the  annular 

ligament,  and,  passing  forwards  and  outwards,  is  inserted  into  the 
whole  length  of  the  radial  side  of  the  metacarpal  bone  of  the  thumb. 
The  action  of  this  powerful  muscle  is  to  oppose  the  thumb  to  all 
the  fingers.  Its  nerve  comes  from  the  median.  Reflect  it  from  its 
insertion,  to  expose  the  following  : — 

FLEXOR  BBEVIS  This  muscle  has  two  origins,  between  which 
POLLICIS.  runs  the  tendon  of  the  flexor  longus  pollicis  :  one, 

the  superficial,  from  the  annular  ligament  and  trapezium  ;  the  other, 
the  deep,  from  the  trapezoid,  os  magnum,  the  bases  of  the  second  and 
third  metacarpal  bones,  and  the  sheath  of  the  tendon  of  the  flexor 
carpi  radialis.  It  is  inserted  by  two  strong  tendons  into  the  base 
of  the  first  phalanx  of  the  thumb ;  the  superficial  tendon  being 
connected  with  the  abductor  pollicis,  and  the  deep  one  with  the 
adductor  pollicis.  A  sesamoid  bone  is  found  in  each  of  the  tendons. 
The  tendons  of  insertion  of  this  muscFe  are  separated  by  the  long 
flexor  tendon  of  the  thumb  and  the  arteria  magna  pollicis.  Its 
action  is  to  bend  the  first  phalanx  of  the  thumb.  The  superficial 
portion  is  supplied  by  the  median  nerve ;  the  deep,  by  the  ulnar. 

ADDUCTOR  POL-  This  triangular  muscle  arises  from  the  palmar 
LICIS.  aspect  of  the  shaft  of  the  metacarpal  bone  of  the 

middle  finger  ;  its  fibres  converge  and  are  inserted,  along  with  the 
deep  or  inner  portion  of  the  flexor  brevis  pollicis,  into  the  base  of 
the  first  phalanx  of  the  thumb  and  the  internal  sesamoid  bone. 
Its  action  is  to  draw  the  thumb  towards  the  palm,  as  when  we 
bring  the  tips  of  the  thumb  and  little  finger  into  contact.  It  is 
supplied  by  the  deep  branch  of  the  ulnar  nerve,  which  also  supplies 
the  deep  head  of  the  flexor  brevis  pollicis.  The  other  muscles  of 
the  ball  of  the  thumb  are  supplied  by  the  median  nerve. 

MUSCLES  OF  THE  The  muscles  of  the  little  finger  correspond  in 
BALL  OF  THE  some  measure  with  those  of  the  thumb.  Thus 

LITTLE  FINGER.  there  is  an  abductor,  a  flexor  brevis,  and  an  op- 


360  MUSCLES   OF   THE   BALL   OF   THE   LITTLE   FINGER. 

ponens  minimi  digiti.  All  derive  their  nerves  from  the  deep  branch 
of  the  ulnar. 

ABDUCTOB  This,  the  most  superficial  of  the  muscles  of  the 

MINIMI  DIGITI.  little  finger,  arises  from  the  pisiform  bone,  and 
from  the  tendinous  expansion  of  the  flexor  carpi  ulnaris  :  it  is  in- 
serted by  a  flat  tendon  into  the  inner  side  of  the  base  of  the  first 
phalanx  of  the  little  finger.  Its  action  is  to  draw  this  finger  from 
the  others.  Its  nerve  comes  from  the  deep  branch  of  the  ulnar. 

FLEXOR  BBEVIS  This  slender  muscle  may  be  considered  as  a  por- 
MINIMI  DIGITI.  tion  of  the  preceding,  to  the  radial  side  of  which 
it  is  situated.  It  arises  from  the  apex  of  the  unciform  bone  and 
annular  ligament,  and  is  inserted  with  the  tendon  of  the  abductor 
into  the  base  of  the  first  phalanx  of  the  little  finger.  Its  action  is 
similar  to  that  of  the  abductor.  Nerve  from  deep  branch  of  ulnar. 
Between  the  origins  of  the  abductor  and  flexor  brevis  minimi  digiti, 
the  deep  branch  of  the  ulnar  artery  and  nerve  sinks  down  to  form 
the  deep  palmar  arch. 

OPPONENS  The  last  two  muscles  must  be  reflected  from 

MINIMI  DIGITI.  their  insertion,  to  expose  the  opponens  minimi 
digiti.  It  arises  from  the  unciform  process  and  the  annular  liga- 
ment, and  is  inserted  along  the  ulnar  side  of  the  shaft  of  the  meta- 
carpal  bone  of  the  little  finger.  Its  action  is  to  draw  this  bone,  the 
most  moveable  of  all  the  metacarpal  bones  of  the  fingers,  towards 
the  thumb.  Thus  it  greatly  strengthens  the  grasp  of  the  palm. 
Nerve  from  deep  branch  of  ulnar. 

Cut  vertically  through  the  anterior  annular 
ligament,  and  observe  that,  with  the  carpal  bones, 
it  forms  an  elliptical  canal,  with  the  broad  diameter  transversely. 
This  canal  is  lined  by  a  synovial  membrane  which  is  reflected 
loosely  over  the  tendons.  Superficial  to  the  ligament  pass  the 
palmaris  longus,  the  ulnar  artery  and  nerve,  the  fibrous  expansion 
from  the  flexor  carpi  ulnaris  covering  these  vessels  and  nerve,  and 
the  palmar  branch  of  the  median  and  ulnar  nerves  ;  beneath  it  pass 
the  superficial  and  deep  flexor  tendons  of  the  fingers,  the  long 
flexor  tendon  of  the  thumb,  and  the  median  nerve.  The  tendon  of 
the  flexor  carpi  radialis  does  not  run  with  the  other  tendons,  but  is 
contained  in  a  distinct  sheath,  lined  by  a  separate  synovial  mem- 


MEDIAN  NERVE  IN  THE  PALM.  361 

brane,  formed,  partly  by  the  annular  ligament,  and  partly  by  the 
groove  in  the  trapezium. 

MEDIAN  NERVE  In  its  passage  under  the  annular  ligament,  the 

IN  THE  PALM.  median  nerve  is  enveloped  in  a  fold  of  synovial 

membrane,  and  lies  upon  the  flexor  tendons.  Here  it  becomes 
enlarged  and  flattened,  and  of  a  pinkish  colour,  and  divides  into 
two  nearly  equal  parts  :  the  external  gives  a  recurrent  branch  to 
the  muscles  of  the  ball  of  the  thumb — namely,  to  the  abductor 
pollicis,  the  opponens  pollicis,  and  the  outer  head  of  the  flexor 
brevis  pollicis,  and  then  terminates  in  three  digital  nerves,  two  of 
which  are  distributed  to  the  thumb,  and  the  third  to  the  radial 
side  of  the  index  finger ;  the  internal  gives  digital  branches  which 
supply  the  ulnar  side  of  the  forefinger,  both  sides  of  the  middle 
finger,  and  the  radial  side  of  the  ring  finger. 

The  two  nerves  to  the  thumb  proceed,  one  on  each  side  of  the  long 
flexor  tendon,  to  the  last  phalanx  :  the  outer  one  being  connected  with 
a  terminal  filament  of  the  radial. 

The  third  digital  nerve  runs  along  the  radial  side  of  the  index  finger. 
The  fourth  descends  towards  the  cleft  between  the  index  and  middle 
fingers,  and  subdivides  into  two  branches,  which  supply  their  opposite 
sides.  The  fifth  is  joined  by  a  filament  from  one  of  the  ulnar  digital 
nerves,  and  then  subdivides  above  the  cleft  between  the  middle  and 
ring  fingers,  to  supply  their  opposite  sides. 

Two  small  branches  are  given  off  from  the  third  and  fourth  digital 
nerves,  to  supply  the  two  radial  lumbricales  ;  the  two  ulnar  being 
supplied  by  the  ulnar  nerve. 

About  an  inch  and  a  quarter  above  the  clefts  between  the  fingers, 
each  digital  nerve  subdivides  into  two  branches,  between  which  the 
digital  artery  passes  and  bifurcates  lower  down  :  therefore  a  vertical 
incision  down  the  cleft  would  divide  the  artery  before  the  nerve. 

In  their  course  along  the  fingers  and  thumb,  the  nerves  lie 
superficial  to  the  arteries,  and  nearer  to  the  flexor  tendons.  About 
the  base  of  the  first  phalanx  each  nerve  sends  a  dorsal  Twancli, 
which  runs  along  the  back  of  the  finger  nearly  to  the  extremity, 
communicating  with  the  dorsal  branches  derived  from  the  radial 
and  ulnar  nerves.1  Near  the  ungual  phalanx  another  dorsal  or 

1  Upon  the  cutaneous  nerves  of  the  hands  and  feet  are  little  bodies,  termed,  after 


362          FLEXOR  TENDONS  AND  THEIR  SHEATHS. 

ungual  branch  is  distributed  to  the  skin  around  and  beneath  the 
matrix  of  the  nail.  Each  digital  nerve  terminates  in  the  cushion 
at  the  end  of  the  finger  in  a  brush  of  filaments,  with  their  points 
directed  into  the  papillas  of  the  skin. 

FLEXOK  TEN-  Immediately  below  the  annular  ligament   the 

DONS  AND  THEIE  tendons  separate  from  each  other  :  near  the  meta- 
SHEATHS.  carpal  joints  they  pass  in  pairs,  through  strong 

fibrous  rings  (p.  355)  formed  by  the  divisions  of  the  palmar  fascia. 
Below  the  metacarpal  joint,  the  two  tendons  for  each  finger  enter 
the  sheath,  theca,  which  confines  them  in  their  course  along  the 
phalanges.  It  is  formed  by  a  strong  fibrous  membrane,  which  is 
attached  to  the  ridges  on  the  phalanges,  and  converts  the  groove 
in  front  of  these  bones  into  a  complete  canal,  exactly  large  enough 
to  contain  the  tendons.  The  density  of  the  sheath  varies  in  par- 
ticular situations,  otherwise  there  would  be  an  obstacle  to  the  easy 
flexion  of  the  fingers.  To  ascertain  this,  cut  open  one  of  the 
sheaths  along  its  entire  length ;  you  will  then  see  that  it  is  much 
stronger  between  the  joints  than  over  the  joints  themselves. 
Through  these  sheaths  inflammation,  commencing  in  the  integu- 
ments of  the  finger,  may  readily  extend  to  the  synovial  membrane 
of  the  tendon. 

In  cases  of  whitlow,  when  pus  forms  in  the  theca,  the  incision 
should  be  made  deep  enough  to  lay  open  this  fibro-osseous  canal, 
without  which  the  incision  will  be  of  no  use.  It  is  obvious  that 
the  incision  should  be  made  down  the  centre  of  the  finger,  to  avoid 
the  digital  nerves  and  arteries.  If  this  opening  be  not  timely 

their  discoverer,  corpuscles  of  Pacini.  Some  of  them  will  be  found,  by  carefully 
examining  the  trunk  of  a  nerve,  or  one  of  its  smaller  branches,  in  the  subcutaneous 
tissue  at  the  root  of  a  finger.  Each  corpuscle  is  about  T^th  of  an  inch  long,  and  is 
attached  by  a  slender  fibre-cellular  pedicle  to  the  nerve  upon  which  it  is  situated  ; 
through  the  pedicle,  a  single  primitive  nerve-fibril  passes  into  the  corpuscle.  The 
corpuscle  itself  is  composed  of  a  series  of  concentric  capsules,  varying  from  twenty 
to  fifty  in  number,  and  separated  by  intervals  containing  fluid :  and  the  nerve- 
fibril  terminates  by  a  dilated  extremity  in  a  central  cavity,  which  exists  in  the 
axis  of  the  corpuscle.  Their  function  is  unknown.  These  bodies  are  found  in 
many  other  situations,  viz.,  in  the  solar  plexus,  the  pudic  nerves,  the  intercostal 
nerves,  the  cutaneous  nerves  of  the  arm  and  neck,  the  infra-orbital  nerve,  the  sacral 
plexus,  and  in  nerves  supplying  the  periosteum.  They  can  be  best  examined 
in  the  mesentery  of  the  cat. 


FLEXOK  TENDONS  IN  THE  PALM.  363 

made,  the  flexor  tendons  are  likely  to  slough,  and  the  finger 
becomes  stiff.1 

But  what  protects  the  joints  of  the  fingers  where  the  flexor 
tendons  play  over  them  ?  Look  into  an  open  sheath,  and  you  will 
see  that  in  front  of  the  joints  the  tendons  glide  over  a  smooth 
fibro-cartilaginous  structure  called  the  palmar  ligament. 

To  facilitate  the  play  of  the  tendons,  the  interior  of  the  sheath, 
as  well  as  the  tendons,  is  lined  by  a  synovial  membrane,  of  the 
extent  of  which  it  is  important  to  have  a  correct  knowledge.  With 
a  probe  you  may  ascertain  that  the  synovial  membrane  is  reflected 
from  the  sheath  upon  the  tendons,  a  little  above  the  metacarpal 
joints  of  the  fingers — that  is,  nearly  in  a  line  with  the  transverse 
fold  in  the  skin  in  the  lower  third  of  the  palm.  Towards  the  distal 
end  of  the  finger,  the  synovial  sheath  stops  short  of  the  last  joint, 
so  that  it  is  not  injured  in  amputation  of  the  ungual  phalanx. 

And  now  notice  how  the  tendons  are  adapted  to  each  other  in 
their  course  along  the  finger.  The  superficial  flexor,  near  the  root 
of  the  finger,  becomes  slightly  grooved  to  receive  the  deep  flexor ; 
about  the  middle  of  the  first  phalanx  it  splits  into  two  portions, 
through  which  the  deep  flexor  passes.  The  two  portions  reunite 
below  the  deep  tendon  so  as  to  embrace  it,  and  then  divide  a 
second  time  into  two  slips,  which  interlace  with  each  other,  and 
are  inserted  into  the  sides  of  the  second  phalanx.  The  deep  flexor, 
having  passed  through  the  opening  of  the  superficial  one,  is 
inserted  into  the  base  of  the  last  phalanx.2 

1  On  closer  inspection  it  will  be  observed  that  the  sheath  is  composed  of  bands 
of  fibres,  which  take  different  directions,  and  have  received  distinct  names.     The 
strongest  are  called  the  ligamenta  vaginalia.    They  constitute  the  sheath  over  the 
body  of  the  phalanx,  and  extend  transversely  from  one  side  of  the  bone  to  the  other. 
The  ligamenta  cruciata  are  two  slips,,  which  cross  obliquely  over  the  tendons.   The 
ligamenta  annularia  are  situated  immediately  in  front  of  the  joints,  and  may  be 
considered  as  thin  continuations  of  the  ligamenta  vaginalia.   They  consist  of  fibres, 
which  are  attached  on  either  side  to  the  lateral  ligaments  of  the  joints,  and  pass 
transversely  over  the  tendons. 

2  In  the  Museum  of  the  College  of  Surgeons,  a  preparation  is  put  up  which 
shows  a  beautiful  piece  of  animal  mechanics  concerning  the  flexor  tendons  ;  namely, 
that  in  its  passage  along  the  phalanges,  the  deep  flexor  forms,  at  the  first  phalanx, 
a  kind  of  little  patella  for  the  superficial  one ;  but,  at  the  second  phalanx,  the 
superficial  flexor  lies  deeper  than  the  other,  and  forms  a  little  patella  for  it.     This 
increases  the  leverage  in  each  case. 


364  LUMBRICALES. 

In  what  way  are  the  tendons  supplied  with  blood  ?  Raise  and 
separate  the  tendons,  and  you  will  see  that  slender  but  very  vas- 
cular folds  of  synovial  membrane  (yincula.'  tendinurn)  run  up  from 
the  phalanges  and  convey  blood-vessels  to  the  tendons. 

The  tendon  of  the  flexor  longus  pollicis  lies  on  the  radial  side  of 
the  other  tendons  beneath  the  annular  ligament.  It  passes  between 
the  two  portions  of  the  flexor  brevis  pollicis  and  the  two  sesamoid 
bones  of  the  thumb,  enters  its  proper  sheath,  and  is  inserted  into 
the  base  of  the  last  phalanx.  Its  synovial  sheath  is  prolonged 
from  the  large  bursa  of  the  flexor  tendons  beneath  the  annular 
ligament,  and  accompanies  the  tendon  down  to  the  last  joint  of  the 
thumb ;  consequently  the  sheath  is  injured  in  amputation  of  the 
last  phalanx. 

BUKSAL  SAC  OF  A  large  and  loose   synovial  sac  (bursa  of  the 

THE  CAKPTJS.  carpus)  facilitates  the  play  of  the  tendons  beneath 

the  anterior  annular  ligament.  It  lines  the  under  surface  of  the 
ligament  and  the  groove  of  the  carpus,  and  is  reflected  in  loose 
folds  over  the  tendons.  It  is  prolonged  up  the  tendons  for  an  inch 
and  a  half,  or  two  inches,  and  forms  a  cul-de-sac  above  the  liga- 
ment. Below  the  ligament  the  bursa  extends  into  the  palm,  and 
sends  off  prolongations  for  each  of  the  flexor  tendons,  which  accom- 
pany them  down  to  the  middle  of  the  hand.  You  will  understand 
that,  when  the  bursa  is  inflamed  and  distended  by  fluid,  there  will 
be  a  bulging  above  the  annular  ligament,  and  another  in  the  palm, 
with  perceptible  fluctuation  between  them ;  the  unyielding  liga- 
ment causing  a  constriction  in  the  centre.1 

These  four  slender  muscles,  one  for  each  finger, 
are  attached  to  the  deep  flexor  tendons  in  the 
palm.  All  of  them  arise  by  fleshy  fibres  from  the  radial  side  and 
palmar  surface  of  the  deep  tendon  of  their  corresponding  finger : 
the  third  and  fourth  also  arise  from  the  adjacent  sides  of  two  ten- 
dons. Each  terminates  in  a  broad  thin  tendon  which  passes  over 

1  In  only  one  subject  have  we  seen  an  instance  in  which  this  bursa  communi- 
cated with  the  wrist-joint.  It  communicates  always  with  the  synovial  sheath  of 
the  long  flexor  of  the  thumb,  in  most  cases  with  that  of  the  flexors  of  the  little 
finger,  and  but  rarely  with  that  of  the  index,  middle,  and  ring  fingers.  For  this 
reason,  inflammation  of  the  theca  of  the  thumb  or  little  finger  is  more  liable  to  be 
attended  with  serious  consequences  than  either  of  the  others. 


RADIAL  AKTERY  IN  THE  PALM.  365 

the  radial  side  of  the  first  joint  of  the  finger,  and  is  inserted,  by  a 
broad  expanded  aponeurosis,  into  the  extensor  tendon  on  the  dorsal 
aspect  of  the  first  phalanx  of  the  finger.  Their  action  is  to  bend 
the  metacarpo-phalangeal  joint  of  the  fingers.  Being  inserted  near 
the  centre  of  motion,  they  can  move  the  fingers  with  great  rapidity. 
As  they  produce  the  quick  motions  of  the  musician's  fingers,  they 
were  called  by  the  old  anatomists  fidicinales. 

The  two  ulnar  lumbricales  are  supplied  by  the  deep  branch  of 
the  ulnar  nerve  ;  the  two  radial  by  the  third  and  fourth  digital 
branches  of  the  median  nerve. 

Now  cut  through  all  the  flexor  tendons,  and  re- 
move the  deep  fascia  of  the  palm,  to  see  the  deep 
arch  of  arteries  and  its  branches.1 


BRA    HE     F  artery,  sinking  into  the  space  between 

THE  KADIAL  AR-  the  first  and  second  metacarpal  bones,  and  between 
TERY  IN  THE  the  two  heads  of  the  abductor  indicis,  enters  the 

PALM*  palm  between  the  inner  head  of  the  flexor  brevis 

and  the  adductor  pollicis,  and  gives  off  three  branches  —  the  arteria 
princeps  pollicis,  the  radialis  indicis,  and  the  palmaris  profunda, 
which  unites  with  the  deep  ulnar  artery  to  form  the  deep  arch. 

The  arteria  princeps  pollicis  runs  behind  the  deep  head  of  the  flexor 
brevis  pollicis  and  in  front  of  the  abductor  indicis  (first  dorsal  inter- 
osseous),  close  along  the  metacarpal  bone  of  the  thumb  :  in  the  interval 
between  the  lower  portions  of  the  flexor  brevis  pollicis,  the  artery 
divides  into  two  digital  branches,  which  proceed  one  on  either  side  of 
the  thumb,  and  inosculate  at  the  apex  of  the  last  phalanx.  Their 
distribution  and  mode  of  termination  are  like  those  of  the  other  digital 
arteries. 

The  arteria  radialis  indicis  runs  between  the  abductor  indicis  and 
adductor  pollicis,  along  the  radial  side  of  the  index  finger  to  the  end, 
where  it  forms  an  arch  with  the  other  digital  artery,  a  branch  of  the 
ulnar.  Near  the  lower  margin  of  the  adductor  pollicis,  the  radialis 
indicis  generally  receives  a  branch  from  the  princeps  pollicis,  and  gives 
a  branch  to  the  superficial  palmar  arch. 

The  palmaris  profunda  may  be  considered  as  the  continuation 

1  The  course  and  relations  of  the  radial  artery  as  it  winds  round  the  wrist  will 
be  described  in  the  dissection  of  the  back  of  the  hand. 


366         MUSCLES   OF   THE   BACK   CONNECTED   WITH   THE    ARM. 

of  the  radial  artery.  It  enters  the  palm  between  the  inner  head  of 
the  flexor  brevis  and  the  adductor  pollicis,  and,  running  upon  the 
bases  of  the  metacarpal  bones,  inosculates  with  the  deep  branch  of 
the  ulnar  artery,  thus  completing  the  deep  palmar  arch.  From  the 
concavity  of  the  arch  small  recurrent  branches  ascend  to  supply  the 
bones  and  joints  of  the  carpus,  inosculating  with  the  other  carpal 
arteries. 

From  the  convexity  of  the  arch  three  or  four  small  branches,  called 
palmar  interosseous  (fig.  83,  p.  356),  descend  to  supply  the  interosseous 
muscles,  and  near  the  clefts  of  the  fingers  communicate  with  the  digital 
arteries.  These  palmar  interosseous  branches  are  sometimes  of  consider- 
able size,  and  take  the  place  of  one  or  more  of  the  digital  arteries,  ordi- 
narily derived  from  the  superficial  palmar  arch.  Three  branches,  called 
perforating,  pass  between  the  upper  ends  of  the  metacarpal  bones  to 
the  back  of  the  hand,  and  communicate  with  the  carpal  branches  of  the 
radial  and  ulnar. 

DEEP  BRANCH  •  This  nerve  sinks  into  the  palm  with  the  ulnaris 
OP  THE  ULNAR  profunda  artery,  between  the  abductor  and  flexor 

NERVE-  brevis  minimi  digiti.  It  then  runs  with  the  deep 

palmar  arch  towards  the  radial  side  of  the  palm,  and  terminates  in 
the  adductor  pollicis,  in  the  inner  or  deep  head  of  the  flexor  brevis 
pollicis,  and  in  the  first  dorsal  interosseous.  Between  the  pisiform 
and  unciform  bones,  the  nerve  gives  a  branch  to  each  of  the  muscles 
of  the  little  finger.  Subsequently  it  sends  branches  to  each  inter- 
osseous muscle  and  to  the  two  inner  lumbricales. 

The  tendon  of  the  flexor  carpi  radialis  in  the  palm  must  now 
be  followed  to  its  insertion  into  the  base  of  the  second  metacarpal 
bone. 

The  dissection  of  the  remaining  muscles  of  the  palm,  called, 
from  their  position,  interossei,  must  be,  for  the  present,  postponed. 


MUSCLES  OF   THE   BACK   CONNECTED   WITH   THE   AEM. 

Make  an  incision  down  the  middle  of  the  spine 
DISSECTION 

from  the  occiput  to  the  sacrum  ;  another,  from  the 

last  dorsal  vertebra  upwards  and  outwards  to  the  acromion ;  and  a 


CUTANEOUS  NERVES  OF  THE  BACK.  367 

third,  from  the  sacrum  along  the  crest  of  the  ilium  ;  then  reflect 
the  skin  outwards  from  the  dense  subcutaneous  tissue,  in  which 
will  be  found  the  following  cutaneous  nerves. 

CUTANEOUS  These  are  derived  from  the  posterior  divisions  of 

NERVES  OF  THE  the  spinal  nerves,  and  correspond,  generally,  to  the 
JBACK-  number  of  the  vertebrae.  The  posterior  primary 

branches,  much  smaller  than  the  anterior,  divide,  between  the 
transverse  processes,  into  external  and  internal  branches,  with  the 
exception  of  the  suboccipital,  the  fourth  and  fifth  sacral,  and  the 
coccygeal  nerves. 

POSTERIOR  The  posterior  primary  branches  of  the  cervical 

BRANCHES  OF  THE  nerves  (except  the  first *)  divide  into  external  and 
CERVICAL  NERVES,  internal  branches :  the  external  are  distributed 
solely  to  some  of  the  muscles  of  the  neck,  and  which  will  be  dis- 
sected later  on  ;  the  internal,  larger  than  the  external,  are  distri- 
buted in  the  following  manner  :  the  second,  or  the  great  occipital 
nerve,  perforates  the  complexus,  and  ramifies  on  the  back  of  the 
scalp  with  the  occipital  artery ;  the  third,  fourth,  and  fifth  nerves, 
after  sending  branches  to  the  multifidus  spinae,  semi-spinalis,  and 
the  complexus,  emerge  through  the  trapezius  close  to  the  spinous 
processes,  and  there  pass  transversely  across  that  muscle  to  supply 
the  skin  over  it ;  the  branch  of  the  third  cervical  nerve  sometimes 
sends  a  branch  to  the  back  of  the  scalp ; 2  the  branches  of  the  sixth, 
seventh,  and  eighth  are  small,  and  are  situated  beneath  the  semi- 
spinalis,  to  which  they  are  distributed. 

POSTERIOR  The  external  branches  become  superficial  between 

BRANCHES  OF  THE  the  longissimus  dorsi  and  the  ilio-costalis,  and  sup- 
DORSAL  NERVES.  p]v  these  muscles  and  the  other  divisions  of  the 
erector  spinse  ;  the  six  lower  supply  cutaneous  nerves  in  the  line 
of  the  angles  of  the  ribs.  The  internal  branches,  as  to  the  upper  six 
dorsal,  emerge  between  the  multifidus  spinae  and  semi-spinalis,  and 
passing  horizontally  outwards,  end  in  branches  to  the  skin  close  to 
the  spinous  processes  ;  that  from  the  second  ramifies  over  the  spine 

1  This  nerve  has  already  been  described  in  the  dissection  of  the  suboccipital 
triangle  (p.  290). 

2  The  internal  branches  of  the  first,  second  and  third  cervical  nerves  form 
a  communication  beneath  the  complexus,   which  is  called   by   Cruveilhier  the 
posterior  cervical  plexus. 


368  NERVES    OF   THE    BACK. 

of  the  scapula ;  the  six  lower  do  not  become  cutaneous,  but  ter- 
minate in  the  multifidus  spinae. 

POSTERIOR  The  external  brandies  from  the  first,  second,  and 

BRANCHES  OF  THE  third  lumbar  nerves  perforate  the  ilio-costalis  and 
LUMBAR  NERVES.  ^he  latissimus  dorsi,  and  then  descend  over  the 
crest  of  the  ilium,  supplying  cutaneous  branches  to  the  gluteal 
region  ;  the  fourth  supplies  the  erector  spinse  without  becoming 
cutaneous  ;  the  fifth  sends  down  a  branch  to  communicate  with  the 
first  sacral  nerve.  The  internal  brandies  are  small,  and  end  in  the 
multifidus  spinse. 

POSTERIOR  Tne  Vernal  brandies  of  the  upper  three  sacral 

BRANCHES  OF  THE  nerves  form  a  series  of  loops  with  themselves,  and 
SACRAL  NERVES.  a}go  w^]1  the  ias^  lumbar  above  and  the  fourth 
sacral  below  ;  they  pass  to  the  superficial  surface  of  the  great  sacro- 
sciatic  ligament,  where  they  form  another  series  of  loops,  from 
which  filaments  are  distributed  to  the  skin  after  piercing  the 
gluteus  maximus.  The  internal  brandies  of  the  three  upper  sacral 
nerves  are  distributed  to  the  multifidus  spinge.  The  posterior 
branches  of  the  fourth  and  fifth  sacral  nerves  do  not  divide  into 
external  and  internal  branches,  but  form  a  loop,  the  lower  one 
being  joined  with  the  coccygeal  nerve. 

COCCYGEAL  The  posterior  division  of  this  nerve,  after  being 

NERVE.  joined  by  a  branch  from  the  last  sa.cral,  is  distri- 

buted to  the  posterior  aspect  of  the  coccyx. 

The  trapezius  and  latissimus  dorsi,  which  form 

the  first  layer  of  muscles,  must  now  be  .cleaned  by 

putting  them  on  the  stretch,  and  reflecting  the  connective  tissue 

which  covers  them  ;  they  should  then  be  dissected  in  the  course  of 

their  fibres. 

Alone,  this  muscle  is  triangular ;  with  its  fel- 
TRAPEZIUS 

low,  it  presents  a  trapezoid  form.     It  arises  from 

the  inner  fourth,  more  or  less,  of  the 'superior  curved  line  of  the 
occiput,  from  the  ligamentum  nuchas,1  from  the  spinous  processes 

1  The  ligamentum  nuchae  is,  in  man,  only  a  rudiment  of  the  great  elastic  liga- 
ment which  supports  the  weight  of  the  head  in  quadrupeds.  It  extends  from  the 
spine  of  the  occiput  to  the  spines  of  all  the  cervical  vertebra,  except  the  atlas  ; 
otherwise  it  would  impede  the  free  rotation  of  the  head.  In  the  giraffe  this  liga- 


FIG.  84. 


369 


a,  n,  Small  occipital  nerve 
from  the  cervical  plexus  ; 

1,  external      muscular 
branches  of  the  first  cer- 
vical nerve  and  union  by 
a  loop  with  the  second  ; 

2,  the  rectus  capitis  posti- 
cus  major,  with  the  great 
occipital    nerve    passing 
round,  the  short  muscles 
and    piercing   the    corn- 
plexus  ;     the     external 
branch    is    seen    to    the 
outside ;  2',  the  great  occi- 
pital ;  3,  external  branch 
of  the  posterior  primary 
division    of     the     third 
nerve  ;    3',    its    internal 
branch,  or  third  occipital 
nerve  ;   4',  5',  6',  7',  8', 
internal  branches  of  the 
several        corresponding 
nerves  on  the  left  side ; 
the  external  branches  of 
these   nerves  proceeding 
to  muscles  are  displayed 
on  the  right  side  :  d  1  to 
d  6,  and  thence  to  d!2,  ex- 
ternal muscular  branches 
of  the  posterior  primary 
divisions  of   the   twelve 
dorsal  nerves  on  the  right 
side  ;  d  1',  to  d  6',  the  in- 
ternal cutaneous  branches 
of  the  six  upper   dorsal 
nerves  on  the  left  side; 
d  T  to  d  12',  cutaneous 
branches  of  the  six  lower 
dorsal  nerves  from  the  ex- 
ternal branches ;  I,  I,  ex- 
ternal branches  of  the  pos- 
terior primary  branches 
of  several  lumbar  nerves 
on  the  right  side  piercing 
the   muscles,    the   lower 
descending  over  the  glu- 
teal  region ;  /',  I',  the  same 
more  superficially  on  the 
left  side  ;  s, «,  on  the  right 
side,  the  issue  and  union 
by  loops  of  the  posterior 
primary  divisions  of  four 
sacral  nerves  ;  i',  s1,  some 
of   these   distributed   to 
the  skin  on  the  left  side. 


DIAGRAM   OF   THE   CUTANEOUS   NERVES   OF   THE    BACK.       (Quain.) 


B  B 


370  TRAPEZIUS. 

of  the  seventh  cervical,  and  all  the  dorsal  vertebrae,  and  from  their 
supraspinous  ligament.  The  fibres  converge  towards  the  shoulder. 
The  upper  pass  downwards  and  outwards,  and  are  inserted  by  fleshy 
fibres  into  the  external  third  of  the  clavicle ;  the  middle  pass 
transversely  outwards  into  the  inner  border  of  the  acromion  and 
the  superior  lip  of  the  spine  of  the  scapula;  the  lower  pass  upwards 
and  outwards,  and  terminate  in  a  thin  tendon,  which  plays  over  the 
triangular  surface  at  the  back  of  the  scapula,  and  is  inserted  into 
the  beginning  of  the  spine.  The  insertion  of  the  trapezius  exactly 
corresponds  to  the  origin  of  the  deltoid,  and  the  two  muscles  are 
connected  by  a  thin  aponeurosis  over  the  spine  and  acromion.  If 
both  the  trapezius  muscles  be  exposed,  observe  that,  between  the 
sixth  cervical  and  the  third  dorsal  vertebrae,  their  origin  presents 
an  aponeurotic  space  of  an  elliptical  form  (p.  371,  fig.  85). 

The  structures  covered  by  the  trapezius  are  :  the  splenius,  the 
complexus,  the  levator  anguli  scapulas,  the  rhomboidei  minor  and 
major,  the  supraspinatus,  a  small  part  of  the  infraspinatus,  the 
serratus  posticus  superior,  the  vertebral  aponeurosis,  the  latissimus 
dorsi,  the  ilio-costalis,  the  spinal  accessory  nerve,  and  the  super- 
ficialis  colli  artery. 

The  fixed  point  of  the  muscle  being  at  the  vertebral  column, 
all  its  fibres  tend  to  raise  the  shoulder.  The  deltoid  cannot  raise 
the  humerus  beyond  an  angle  of  ninety  degrees  :  beyond  this,  the 
elevation  of  the  arm  is  principally  effected  by  the  rotatory  move- 
ment of  the  scapula.  The  trapezius  is  in  strong  action  when  a 
weight  is  borne  upon  the  shoulders  ;  again,  its  middle  and  inferior 
fibres  act  powerfully  in  drawing  the  scapula  backwards,  as  in  pre- 
paring to  strike  a  blow.  If  both  muscles  act,  they  draw  the  head 
backwards  ;  if  one  only  acts,  it  draws  the  head  to  the  same  side. 
It  is  supplied  by  the  nervus  accessorius  and  the  deep  branches  of 
the  cervical  plexus,  and  by  the  superficialis  colli  artery. 

LATISSIMUS  This  broad  flat  muscle  occupies  the  lumbar  and 

DOBSI.  lower  dorsal  regions,  and  thence  extends  to  the 

arm,  where  it  forms  part  of  the  posterior  boundary  of  the  axilla. 
It  arises  from  the  posterior  third  of  the  external  lip  of  the  crest 

ment  is  six  feet  long,  and  as  thick  as  a  man's  forearm.  Professor  Quekett  states 
that  when  divided  it  shrinks  at  least  two  feet. 


SUPERFICIAL    MUSCLES    OF   THE    BACK. 
FIG.  85. 


371 


THE    SUPERFICIAL   MUSCLES 


372  LATISSIMUS   DORSI. 

of  the  ilium,  from  the  spinous  processes  of  the  two  upper  sacral, 
all  the  lumbar  and  the  six  lower  dorsal  vertebrae,  and  their  supra- 
spinous  ligament,  by  a  strong  aponeurosis ;  and,  lastly,  from  the 
three  or  four  lower  ribs  by  fleshy  slips,  which  interdigitate  with 
those  of  the  external  oblique  muscle  of  the  abdomen.  All  the 
fibres  converge  towards  the  axilla,  where  they  form  a  thick  muscle, 
which  curves  over  the  inferior  angle  of  the  scapula,  and  is  inserted 
by  a  broad,  flat  tendon  into  the  bottom  of  the  bicipital  groove  of 
the  humerus.  The  upper  fibres  are  inserted  into  the  lowest  of  the 
groove,  the  lower  fibres  into  the  upper  part.  The  tendon  is  about 
two  inches  broad,  and  lies  in  front  of,  and  higher  than  that  of  the 
pectoralis  major  and  of  the  teres  major,  from  which  it  is  separated 
by  a  large  lursa.1  It  is  supplied  mainly  by  the  long  subscapular 
nerve, .also  by  the  posterior  branches  of  the  dorsal  and  lumbar 
nerves. 

The  latissimus  dorsi  draws  the  humerus  inwards  and  back- 
wards; rotating  it  also  inwards.  It  co-operates  with  the  pectoralis 
major  in  pulling  any  object  towards  the  body :  if  the  humerus  be 
the  fixed  point,  it  raises  the  body,  as  in  climbing.  The  object  of 
the  muscle  arising  so  high  up  the  back  is,  that  the  transverse 
fibres  of  the  muscle  may  strap  down  the  inferior  angle  of  the 
scapula.  It  sometimes  happens  that  the  scapula  slips  above  the 
muscle  :  this  displacement  is  readily  recognised  by  the  unnatural 
projection  of  the  lower  angle  of  the  bone,  and  the  impaired  move- 
ments of  the  arm.2 

The  muscle  covering  the  latissimus  dorsi  is  thetrapezius  above; 
those  lying  beneath  it  are,  a  small  part  of  the  rhomboideus  major, 
of  the  infraspinatus,  and  of  the  teres  major,  the  serratus  posticus 
inferior,  the  spinalis  dorsi,  the  longissimus  dorsi,  the  ilio-costalis, 
and  the  external  intercostals.  Between  the  base  of  the  scapula, 

1  The  latissimus  dorsi  frequently  receives  a  distinct  accessory  slip  from  the 
inferior  angle  of  the  scapula. 

2  We  have  seen  several  instances  of  this  displacement.     There  is  great  pro* 
jection  of  the  inferior  angle  of  the  scapula,  especially  when  the  patient  attempts 
to  raise  the  arm.    He  cannot  raise  the  arm  beyond  a  right  angle,  unless  firm  pres- 
sure is  made  on  the  lower  angle  of  the  scapula,  so  as  to  supply  the  place  of  the 
muscular  strap.    Whether  the  scapula  can  be  replaced  or  not,  a  firm  bandage 
should  be  applied  round  the  chest. 


SPINAL   ACCESSORY   NERVE.  373 

the  trapezius,  and  the  upper  border  of  the  latissimus  dorsi,  a  tri- 
angular space  is  observed  when  the  arm  is  raised,  in  which  the 
lower  fibres  of  the  rhomboideus  major  and  part  of  the  sixth  in- 
tercostal space  are  exposed.  Immediately  above  the  crest  of  the 
ilium,  between  the  free  margins  of  the  latissimus  dorsi  and  external 
oblique,  there  is,  also,  an  interval  in  which  a  little  of  the  internal 
oblique  can  be  seen. 

LUMBAB  OB  This   dense   shining   aponeurosis   of  the   back 

VERTEBRAL  (sometimes  termed  the  aponeurosis  of  the  latissi- 

APONEUROSIS.  mus  dorsi)  forms  the  posterior  part  of  the  sheath 

of  the  erector  spinas.  It  is  pointed  above,  where  it  is  continuous 
with  the  deep  cervical  fascia,  broader  and  stronger  below.  It 
consists  of  tendinous  fibres,  which  are  attached  internally  to  the 
spines  of  the  dorsal,  all  the  lumbar  and  sacral  vertebrae ;  exter- 
nally, to  the  angles  of  the  ribs ;  and  inferiorly  it  is  blended  with 
the  tendons  of  the  serratus  posticus  inferior  and  latissimus  dorsi. 
When  suppuration  takes  place  in  the  loins,  constituting  a  lumbar 
abscess  in  connection  with  spinal  disease,  the  pus  is  seated  beneath 
this  aponeurosis,  and  is  therefore  tardy  in  coming  to  the  surface. 

Reflect  the  trapezius  from  its  insertion.     On  its 
DISSECTION 

under  surface  see  the  ramifications  of  its  nutrient 

artery,  the  superficialis  colli,  a  branch  of  the  posterior  scapular. 
A  large  nerve,  the  spinal  accessory,  enters  its  under  surface  near 
the  clavicle,  and  divides  into  filaments,  which,  reinforced  by  fila- 
ments from  the  third  and  fourth  cervical  nerves,  are  distributed  to 
the  muscle  as  far  as  its  lower  border. 

SPINAL  ACCES-  This  nerve,  the  eleventh  cerebral  nerve,  arises 

,SOBY  NERVE.  by  two  roots — the  accessory  and  the  spinal  por- 

tions :  the  former  from  the  medulla  oblongata,  the  latter  from  the 
spinal  cord.  The  accessory  portion,  the  smaller,  arises  by  four  or 
five  filaments  from  a  grey  nucleus  in  the  floor  of  the  fourth  ventricle, 
below  the  origin  of  the  pneumogastric  nerve ;  the  spinal  portion 
arises  from  the  lateral  part  of  the  cervical  portion  of  the  spinal 
cord  by  several  filaments,  some  of  which  arise  as  low  as  the  sixth 
cervical  vertebra,  and  which  may  be  traced  into  the  grey  matter  of 
the  anterior  horn.  Formed  by  the  union  of  these  roots,  the  nerve 
-enters  the  skull  through  the  foramen  magnum,  and  leaves  it  again, 


874  RHOMBOIDEI. 

with  the  accessory  portion,  through  the  foramen  jugulare.  These 
portions  communicate  external  to  the  skull ;  but  while  the  acces- 
sory root  joins  the  vagus,  the  spinal  portion,  in  the  main,  runs 
behind  the  internal  jugular  vein,  traverses  obliquely  the  upper  third 
of  the  sterno-mastoid  muscle,  and  crosses  the  posterior  triangle  of 
the  neck  to  the  trapezius,  which  it  supplies  (p.  74).  In  front  of 
the  trapezius  it  is  joined  by  branches  from  the  third,  fourth,  and 
fifth  cervical  nerves,  together  with  which  it  communicates  with  the 
posterior  branches  of  the  spinal  nerves. 

The  trapezius  should  now  be  cut  through  the  middle,  and  the 
inner  half  turned  inwards  towards  the  spine,  the  outer  half  over 
the  clavicle  and  the  spine  of  the  scapula. 

Beneath  the  trapezius  we  have  to  examine  the  second  layer, 
consisting  of  three  muscles  connected  with  the  scapula ;  namely, 
the  levator  anguli  scapulae,  the  rhomboideus  major  and  minor. 
The  scapula  should  be  adjusted  so  as  to  stretch  their  fibres. 

LEVATOR  This  muscle  is  situated  at  the  back  and  side  of 

ANGULI  SCAPULA.  the  neck.  It  arises  by  four  tendons  from  the 
posterior  tubercles  of  the  transverse  processes  of  the  four  upper 
cervical  vertebrae.  The  muscular  slips  to  which  the  tendons  give 
rise  form  a  single  muscle,  which  descends  outwards  along  the  side 
of  the  neck,  and  is  inserted  into  the  posterior  border  of  the  scapula 
between  its  spine  and  superior  angle.  Its  action  is  to  raise  the 
posterior  angle  of  the  scapula ;  as,  for  instance,  in  shrugging  the 
shoulders.  Its  nerve  comes  from  the  fifth  cervical,  and  by  fila- 
ments from  the  external  series  of  the  deep  cervical  plexus,  which 
come  from  the  third  and  fourth  cervical  nerves. 

BHOMBOIDEUS  These    flat   muscles   extend  from  the    spinous 

MAJOR  AND  processes  of  the  vertebrae  to  the  base  of  the  scapula. 

MlNOK<  They  often    appear  like   a  single  muscle.      The 

rhomboideus  minor,  the  higher  of  the  two,  arises  by  a  thin  apo- 
neurosis  from  the  spinous  processes  of  the  last  cervical  and  the  first 
dorsal  vertebrae,  and  is  inserted  into  the  base  of  the  scapula  oppo- 
site its  spine.  The  rhomboideus  major  arises  by  tendinous  fibres 
from  the  spinous  processes  of  the  four  or  five  upper  dorsal  vertebras 
and  the  supraspinous  ligament,  and  is  inserted  by  fleshy  fibres 
into  the  base  of  the  scapula  between  its  spine  and  inferior  angle ;. 


SUPRASCAPULAR   ARTERY.  375 

the  larger  number  of  the  fibres  being  inserted  into  a  tendinous 
arch,  which  is  chiefly  attached  to  the  inferior  angle.  The  action 
of  these  muscles  is  to  draw  the  scapula  upwards  and  backwards. 
They  are  the  antagonists  of  the  serratus  magnus. 

The  nerve  of  the  rhomboid  muscles  (posterior  scapular)  is  a 
branch  of  the  fifth  cervical.  It  passes  outwards  beneath  the  lower 
part  of  the  levator  anguli  scapulae,  to  which  it  sends  a  branch,  and 
is  lost  in  the  under  surface  of  the  rhomboidei. 

This  muscle  extends  from  the  scapula  to  the 

OMO-HYOIDEUS.  ,       .  -,  -,  .  ,        „  ,         -. 

os  hyoides,  and  consists  01  two  long  narrow  mus- 
cular portions,  connected  by  an  intermediate  tendon  beneath  the 
sterno-mastoid.  The  posterior  portion  only  can  be  seen  in  the  pre- 
sent dissection.  It  arises  from  the  upper  border  of  the  scapula,  close 
behind  the  notch,  and  from  the  transverse  ligament  above  the  notch. 
Thence  the  slender  muscle  passes  forwards  across  the  lower  part  of 
the  neck,  beneath  the  sterno-mastoid,  where  it  changes  its  direc- 
tion and  ascends  nearly  vertically,  to  be  attached  to  the  os  hyoides 
at  the  junction  of  the  body  with  the  greater  cornu  (p.  79).  Thus 
the  two  portions  of  the  muscle  form,  beneath  the  sterno-mastoid, 
an  obtuse  angle,  of  which  the  apex  is  tendinous,  and  of  which  the 
angular  direction  is  maintained  by  a  layer  of  fascia,  proceeding 
from  the  tendon  to  the  first  rib  and  the  clavicle.  Its  action  is  to 
depress  the  os  hyoides.  Its  nerve  comes  from  the  descendens  noni 
and  the  communicantes  noni  (p.  110). 

SUPRASCAPDLAR          This  artery  (transversalis  hunieri),  a  branch  of 
ARTERY.  the  thyroid  axis  (p.  121),  runs  behind  andparalle1 

with  the  clavicle,  over  the  lower  end  of  the  scalenus  anticus  and 
subclavian  artery,  and  beneath  the  sterno-mastoid  and  omo-hyoid 
muscles,  to  the  upper  border  of  the  scapula,  where  it  usually  passes 
above  the  ligament  bridging  over  the  notch.  It  ramifies  in  the 
supraspinous  fossa,  supplying  the  supraspinatus,  and  then  passes 
under  the  acromion  to  the  infraspinous  fossa,  where  it  inosculates 
freely  with  the  dorsalis  scapulas,  a  branch  of  the  subscapular.  It 
sends  off — 

a.  The  inferior  sterno-mastoid  artery  -to  the  sterno-mastoid  and 
contiguous  muscles  ;  b.  the  siipra-a,cromial  branch,  which  ramifies 
upon  the  acromion,  anastomosing  with  the  other  acromial  arteries 


376  POSTERIOR   SCAPULAR   NERVE. 

derived  from  branches  of  the  axillary  ;  c.  a  small  subscapular  branch 
to  the  fossa  of  the  same  name  ;  d.  articular  arteries  to  the  shoulder- 
joint  ;  and,  lastly,  e.  the  infraspinotis  branch,  which  anastomoses  with 
the  dorsalis  scapulae.  The  suprascapular  vein  terminates  either  in  the 
subclavian  or  in  the  external  jugular. 

The  suprascapular  nerve,  a  branch  of  the  fifth  and  sixth  cer- 
vical nerves,  runs  with  the  corresponding  artery,  and,  after  pass- 
ing through  the  suprascapular  notch,  is  distributed  to  the  supra- 
spinatus  and  infraspinatus.  In  the  supraspinous  fossa,  this  nerve 
sends  a  small  articular  branch  to  the  shoulder-joint ;  in  the  infra- 
spinous  fossa  it  gives  off  two  branches  to  the  infraspinatus,  and 
some  to  the  shoulde'r-joint. 

POSTERIOR  This  artery  is  one  of  the  divisions  of  the  trans- 

SCAPDLAR  versa!  is  colli,  but  comes  very  frequently  from  the 

ARTERY.  subclavian  in  the  third  part  of  its  course  (p.  121). 

It  runs  across  the  lower  part  of  the  neck,  above,  or  between  the 
nerves  of  the  brachial  plexus,  towards  the  posterior  superior  angle 
of  the  scapula.  Here  it  pursues  its  course  along  the  posterior 
border  of  the  scapula  beneath  the  levator  angulis  capulse  and 
the  rhomboidei,  anastomosing  with  branches  of  the  suprascapular 
and  subscapular  arteries,  and  with  branches  from  the  intercostal 
arteries.  The  corresponding  vein  joins  the  external  jugular  or  the 
subclavian. 

Divide  the  rhomboid  muscles  near  their  inser- 
tion, and  trace  the  artery  to  the  inferior  angle 
of  the  scapula,  where  it  terminates  in  the  rhomboidei,  serratus 
magnus,  and  latissimus  dorsi. 

Numerous  muscular  branches  arise  from  the  posterior  scapular. 
The  superftcialis  colli  (the  other  division  of  the  transversalis  colli) 
is  given  off  near  the  upper  angle  of  the  scapula  for  the  supply  of 
the  trapezius,  which  it  enters  together  with  the  spinal  accessory 
nerve. 

Divide  and  reflect  the  latissimus  dorsi  below  the  inferior  angle 
of  the  scapula,  and  draw  the  scapula  forcibly  outwards,  to  have  a 
more  perfect  view  of  the  extent  of  the  serratus  magnus  than  was 
seen  in  the  axilla.  The  abundance  of  connective  tissue  in  this 
situation  is  necessary  for  the  play  of  the  scapula  on  the  chest. 


SERRATUS   MAGNUS.  377 

SEEEATUS      .  This  broad,  thin,  flat  muscle  intervenes  between 

MAGNUS.  the  scapula  and  the  ribs.     It  arises  by  nine  fleshy 

•digitations  from  the  eight  upper  ribs,  each  rib  giving  origin  to  one, 
and  the  second  to  two,  and  from  the  fascia  covering  the  correspond- 
ing intercostal  spaces.  The  four  lower  digitations  correspond  with 
those  of  the  external  oblique  muscle  of  the  abdomen.  The  fibres 
pass  backwards  and  outwards  and  are  arranged  in  three  fasciculi ; 
the  upper  portion  arises  from  the  first  and  second  ribs  and  the 
fascia  between  them,  and  is  inserted  into  the  triangular  surface  in 
front  of  the  upper  angle  of  the  scapula ;  the  middle  portion  arises 
from  the  second,  third,  and  fourth  ribs,  and  is  inserted  into  the 
inner  lip  of  the  vertebral  border  between  the  first  and  third  por- 
tions ;  the  third  portion  arises  from  the  fifth,  sixth,  seventh,  and 
eighth  ribs,  and  is  inserted  into  the  smooth  surface  in  front  of  the 
inferior  angle;  this  last  portion  consists  of  four  serrations,  and 
are  those  which  interdigitate  with  the  external  oblique. 

This  is  the  most  important  of  the  muscles  which  regulate  the 
movements  of  the  scapula.  It  draws  the  scapula  forwards,  and  thus 
gives  additional  reach  to  the  arm ;  it  counteracts  all  forces  which 
tend  to  push  the  scapula  backwards  ;  for  instance,  when  a  man  falls 
forwards  upon  his  hands,  the  serratus  magnus  sustains  the  shock, 
and  prevents  the  scapula  from  being  driven  back  to  the  spine. 
Supposing  the  fixed  point  to  be  at  the  scapula,  some  anatomists 
ascribe  to  it  the  power  of  raising  the  ribs ;  hence  Sir  Charles  Bell 
called  it  the  external  respiratory  muscle,  the  internal  respiratory 
muscle  being  the  diaphragm. 

The  nerve  which  supplies  it  is  a  branch  of  the  fifth  and  sixth 
cervical  nerve :  it  descends  along  its  outer  surface,  distributing  a 
filament  to  each  digitation  of  the  muscle  (p.  126). 

Divide  the  serratus  magnus  near  the  scapula, 
and  remove  the  arm  by  sawing  through  the  middle 
of  the  clavicle,  cutting  through  the  axillary  vessels  and  nerves. 
These  should  be  tied  to  the  coracoid  process.  After  the  removal 
of  the  arm,  examine  the  precise  insertions  of  the  preceding 
muscles. 


378 


DISSECTION    OF   THE    MUSCLES    OF   THE    SHOULDER. 


DISSECTION   OF   THE   MUSCLES   OF   THE    SHOULDEB. 


DISSECTION. 


The  remainder  of  the  skin  over  the  shoulder  is 
to  be  reflected,  and  in  the  subcutaneous  tissue  are 
found  the  cutaneous  vessels  and  nerves.  Some  pass  down  over  the 
shoulder,  others  ascend  over  the  deltoid,  emerging  from  beneath  its 
lower  border. 

The  acromial  branches  come  from  the  third  and  fourth  cervical 


FIG.  86. 


1.  Supra-aoromial  br.  of  the 

cervical  nerves. 

2.  Ascending  and  descend- 

ing brs.  of  the  circum- 
flex n. 

3.  4.  Cutaneous  brs.  of  the 

musculo-cutaneous  u. 

5.  Internal  cutaneous  br.of 
musculo-spiral  n. 


6.  Intercosto-humeral 

brs. 

7.  Filaments  of  the  lesser 

internal  cutaneous  n. 

8.  Posterior      cutaneous 

br.  of  internal  cuta- 
neous n. 

9.  Branch  of  internal  cu- 

taneous n. 


CUTANEOUS    NEEVES    OF    THE    LEFT    SHOULDER   AND    ARM.       (POSTERIOR    VIEW.) 

nerves,  and  descend  over  the  acromion  (fig.  86)  in  front  of, 
and  behind,  the  deltoid.  The  cutaneous  branch  of  the  circumflex 
nerve  comes  out  beneath  the  posterior  border  of  the  deltoid,  and 
supplies  the  skin  over  the  posterior  and  outer  two-thirds  of  the 


THE    DELTOID.  379 

muscle ;  others  perforate  the  muscle,  each  accompanied  by  a  small 
artery. 

Notice  the  strong  layer  of  fascia  upon  the  surface  of  the  deltoid, 
which  extends  from  the  aponeurosis  covering  the  muscles  on  the 
back  of  the  scapula,  and  is  continuous  with  the  fascia  of  the  arm. 
It  dips  down  between  the  fibres  of  the  muscle,  dividing  it  into 
large  bundles.  This  fascia  is  to  be  removed,  by  putting  the  deltoid 
on  the  stretch,  and  reflecting  it  in  the  direction  of  its  fibres,  begin- 
ning from  the  front.  The  fascia  will  be  seen  to  be  continuous  in 
front  with  the  fascia  covering  the  pectoralis  major:  above,  it  is 
attached  to  the  clavicle  and  spine  of  the  scapula ;  behind,  it  is 
continuous  with  that  over  the  infraspinatus. 

The  large  muscle  which  covers  the  shoulder- 
joint  is  named  deltoid,  from  its  resemblance  to  the 
Greek  A  reversed.  It  arises  from  the  external  third  of  the  anterior 
border  of  the  clavicle,  from  the  apex  and  outer  border  of  the  acro- 
mion,  and  from  the  lower  border  of  the  spine  of  the  scapula  down 
to  the  triangular  surface  at  its  root.  This  origin,  which  corresponds 
to  the  insertion  of  the  trapezius,  is  tendinous  and  fleshy  everywhere, 
except  at  the  commencement  of  the  spine  of  the  scapula,  where  it 
is  simply  tendinous,  and  connected  with  the  infraspinous  aponeu- 
rosis. The  muscular  fibres  descend,  the  anterior  backwards,  the 
posterior  forwards,  the  middle  perpendicularly ;  all  converge  to  a 
tendon  which  is  inserted  into  a  rough  surface  on  the  outer  side  of 
the  humerus,  a  little  above  the  middle  of  the  shaft.  The  insertion 
of  the  tendon  extends  one  inch  and  a  half  along  the  humerus,  and 
terminates  in  a  y-shaped  form,  the  origin  of  the  brachialis  anticus 
embracing  it  on  either  side.  Sometimes  a  few  fibres  of  the  pecto- 
ralis major  are  connected  with  its  front  border. 

The  muscular  bundles  composing  the  deltoid  have  a  peculiar 
arrangement :  a  peculiarity  arising  from  its  broad  origin  and  its 
narrow  insertion.  It  consists  in  the  interposition  of  tendons 
between  the  bundles  for  the  attachment  of  the  muscular  fibres. 
The  annexed  woodcut  shows  this  arrangement  better  than  any 
description.  The  action  of  the  muscle  is  not  only  concentrated 
upon  one  point,  but  its  power  is  also  greatly  increased  by  this 
arrangement. 


380 


STRUCTURES  COVEKED  BY  THE  DELTOID. 


FIG.  87. 


ACTION  OF  THE  It  raises  the  arm ;  but  it  cannot  do  so  beyond 

DELTOID.  an  angle  of  ninety  degrees.     The  elevation  of  the 

arm  beyond  this  angle  is  effected  through  .the  raising  of  the  shoulder 
by  the  trapezius  and  serratus  magnus.  Its  anterior  fibres  draw 
the  arm  forwards  ;  its  posterior,  backwards. 

This  powerful  muscle  is  sup- 
plied with  blood  by  the  anterior 
and  posterior  circumflex,  the  thor- 
acica  humeraria,  the  thoracica  acro- 
niialis,  all  from  the  axillary  artery ; 
also  by  the  deltoid  branch  of  the 
brachial.  Its  nerve  is  the  circum- 
flex. 

The  rotundity  of  the  shoulder  is 
due,  not  so  much  to  the  deltoid  as 
to  the  upper  end  of  the  humerus. 
When  the  head  of  the  humerus  is 
dislocated  into  the  axilla,  the  fibres 
of  the  muscle  run  vertically  to  their 
insertion ;  hence  the  flattening  of 
the  deltoid,  and  the  greater  pro- 
minence of  the  acromion. 

It  is  below  the  deltoid  that  an 
ununited  fracture  of  the  humerus  is 

most  commonly  met  with,  owing  to  the  muscle  displacing  the  upper 
fragment. 

Reflect  the  deltoid  from  its  origin,  and  turn  it 
downwards.  Observe  the  ramifications  of  the  cir- 
cumflex nerve  and  the  anterior  and  posterior  circumflex  arteries  on 
its  under  surface ;  notice  also  the  large  bursa  between  it  and  the 
tendons  inserted  into  the  great  tuberosity  of  the  humerus. 

PAKTS  COVERED  The  structures  seen  on  reflecting  the  deltoid  are 

BY  THE  DELTOID.  as  follows :  the  bursa  already  alluded  to,  the  cora- 
coid  process,  the  coraco-acromial  ligament,  the  origins  of  the  biceps 
and  coraco-brachialis,  the  insertions  of  the  pectoralis  minor  and 
major,  the  long  head  of  the  biceps,  the  insertions  of  the  supra- 
spinatus,  infraspinatus,  and  teres  minor,  the  long  and  external 


ANALYSIS    OF    THE    DELTOID. 


DISSECTION. 


CIRCUMFLEX    NERVE.  381 

heads  of  the  triceps,  the  circumflex  vessels  and  nerve,  and  the  neck 
and  upper  part  of  the  humerus. 

BUBSA  UNDER  The  large  bursa  under  the  deltoid  extends  for 

THE  DELTOID,  OR  some  distance  beneath  the  acromion  and  the  coraco- 
SUB-ACROMIAL.  acromial  ligament,  and  covers  the  tendons  attached 
to  the  great  tuberosity  of  the  humerus.  It  communicates,  very 
rarely,  with  the  shoulder-joint.  Its  use  is  to  facilitate  the  move- 
ments of  the  head  of  the  bone  under  the  acromial  arch. 

POSTERIOR  This  artery  is  given  off  from  the  axillary  in  the 

CIRCUMFLEX  third  part  of  its  course ;  it  runs  behind  the  surgical 

ARTERY.  neck  of  the  humerus,  through  a  quadrilateral  open- 

ing, bounded  above  by  the  subscapularis  and  teres  minor ;  below, 
by  the  teres  major ;  externally,  by  the  neck  of  the  humerus  ;  and 
internally,  by  the  long  head  of  the  triceps  (p.  318).  Its  branches 
terminate  on  the  under  surface  of  the  deltoid,  anastomosing  with  the 
anterior  circumflex,  acromial  thoracic,  and  suprascapular  arteries. 

From  the  posterior  circumflex,  a  branch  descends  in  the  sub- 
stance of  the  long  head  of  the  triceps,  to  inosculate  with  the  supe- 
rior profunda :  this  is  one  of  the  channels  through  which  the 
circulation  would  be  carried  on,  if  the  axillary  were  tied  in  the  last 
part  of  its  course. 

CIRCUMFLEX  This  nerve,  a  branch  of  the  posterior  cord  of  the 

NERVE,  axillary  plexus,  runs  with  the  posterior  circumflex 

artery,  through  the  same  quadrilateral  space,  and  then  divides  into 
two  branches — an  upper  and  a  lower.  The  upper  branch  winds 
round  the  neck  of  the  humerus,  and  supplies  the  anterior  part  of 
the  deltoid,  and  gives  off  cutaneous  branches  to  supply  the  skin 
over  its  lower  part.  The  lower  branch  sends  a  filament  to  the  teres 
minor,  one  or  two  to  the  integuments  over  the  shoulder  at  its  pos- 
terior part,  and  terminates  in  the  substance  of  the  deltoid.  It  also 
distributes  an  articular  filament,  which  enters  the  shoulder-joint  in 
front,  below  the  subscapularis. 

The  proximity  of  this  nerve  to  the  head  of  the  humerus  ex- 
plains the  occasional  paralysis  of  the  deltoid,  after  dislocation  or 
fracture  of  the  humerus.  The  nerve  is  liable  to  be  injured,  if  not 
actually  lacerated,  by  the  pressure  of  the  bone.  In  the  summer  of 
1840,  a  man  was  admitted  into  the  hospital  with  a  severe  injury 


382  TERES   MAJOR   AND    MINOR. 

to  the  shoulder,  and  died  of  delirium  tremens.  On  examination 
the  humerus  was  found  broken  high  up,  the  capsule  of  the  joint 
opened,  and  the  circumflex  nerve  torn  completely  across.1  * 

A  strong  aponeurosis  covers  the  muscles  of  the  dorsum  of  the 
scapula,  and  is  firmly  attached  to  the  spine  and  borders  of  the 
bone.  At  the  posterior  edge  of  the  deltoid,  it  divides  into  two 
layers,  one  of  which  passes  over,  the  other  under,  the  muscle. 
Remove  the  aponeurosis,  so  far  as  it  can  be  done  without  injury  to 
the  muscular  fibres  which  arise  from  its  under  surface. 

INFBA-  This  triangular  muscle  arises  by  fleshy  fibres  from 

SPINATUS.  the  posterior  two-thirds  of  the  infraspinous  fossa, 

by  tendinous  fibres  from  the  ridges  on  the  fossa,  and  from  the  apo- 
neurosis which  covers  it.  The  fibres  converge  to  a  tendon,  which  is 
at  first  contained  in  the  substance  of  the  muscle,  and  then  proceeds, 
over  the  capsular  ligament  of  the  shoulder-joint,  to  be  inserted  into 
the  middle  depression  on  the  greater  tuberosity  of  the  humerus. 
Its  nerve  comes  from  the  suprascapular. 

This  long  narrow  muscle  is  situated  below  the 
infraspinatus,  along  the  inferior  border  of  the 
scapula.  It  arises  from  the  dorsum  of  the  scapula  close  to  the 
inferior  border,  and  from  the  intermuscular  septa  between  it  and 
the  infraspinatus  above  and  the  teres  major  below.  The  fibres 
ascend  outwards  parallel  with  those  of  the  infraspinatus,  and  ter- 
minate in  a  tendon,  which  passes  over  the  capsular  ligament  of 
.the  shoulder-joint,  and  is  inserted  into  the  lowest  depression  on 
the  great  tuberosity  of  the  humerus,  and  by  muscular  fibres  into 
the  bone  below  it.  It  is  supplied  by  a  branch  of  the  circumflex 
nerve,  which  enters  the  muscle  at  its  lower  border,  and  it  has 
(usually)  a  small  ganglion-like  enlargement  upon  it. 

The  action  of  the  infraspinatus  and  teres  minor  is  to  rotate  the 
humerus  outwards,  and  when  the  arm  is  raised  it  draws  the  humerus 
downwards  and  backwards. 

This  muscle  is  closely  connected  with  the  latis- 
TEEKS  MAJOR.  .  .  .         . 

simus  dorsi,  and  extends  from  the  inferior  angle 

of  the  scapula  to  the  humerus,  contributing  to  form  the  posterior 
boundary  of  the  axilla.  It  arises  from  the  flat  surface  on  the  dorsal 

1  See  preparation  in  Museum  of  St.  Bartholomew's  Hospital. 


SUBSCAPULARIS.  383 

aspect  of  the  inferior  angle  of  the  back  of  the  scapula,  from  its 
inferior  border,  and  the  intermuscular  septa,  and  terminates  upon  a 
flat  tendon,  nearly  two  inches  in  breadth,  which  is  inserted  into  the 
inner  edge  of  the  bicipital  groove  of  the  humerus,  behind  and  a 
little  lower  than  the  tendon  of  the  latissimus  dorsi.  Its  action  is 
to  draw  the  humerus  backwards  and  downwards  when  the  arm 
is  raised,  and  to  rotate  it  slightly  inwards.  It  is  supplied  by  the 
middle  subscapular  nerve,  which  enters  it  on  its  axillary  aspect. 

A  bursa  is  found  in  front  of,  and  another  behind,  the  tendon  of 
the  teres  major  ;  the  former  separates  it  from  the  latissimus  dorsi, 
the  latter  from  the  bone. 

gUPEA.  This  muscle  arises  from  the  posterior  two-thirds 

SPINATUS.  of  the  supraspinous  fossa,  and  from  its  aponeurotic 

covering.  It  passes  under  the  acromion,  over  the  capsular  liga- 
ment of  the  shoulder-joint,  and  is  inserted  by  a  strong  tendon  into 
the  superior  depression  on  the  greater  tuberosity  of  the  humerus. 
To  see  its  insertion,  the  acromion  should  be  sawn  off  near  the  neck 
of  the  scapula.  Its  action  is  to  assist  the  deltoid  in  raising  the 
arm.  It  is  supplied  by  two  branches  derived  from  the  supra- 
scapular  nerve. 

This  triangular  fleshy  muscle  occupies  the  sub- 

SUBSCAPULARIS.  ~\         C  TM-  •  f  4/L  il 

scapular  fossa.  It  arises  from  the  posterior  three- 
fourths  of  the  fossa,  except  the  posterior  border  and  angles  which 
give  attachment  to  the  serratus  magnus,  and  from  three  or  four 
tendinous  septa  attached  to  the  oblique  bony  ridges  on  its  surface. 
The  fibres,  passing  upwards  and  outwards,  converge  towards  the 
neck  of  the  scapula,  where  they  terminate  upon  three  or  four 
tendons,  which  are  concealed  amongst  the  muscular  fibres,  and  are 
inserted  into  the  lesser  tuberosity  of  the  humerus  and  into  the  bone 
for  an  inch  below  the  tuberosity.  Its  broad  insertion  is  closely  con- 
nected with  the  capsule  of  the  shoulder-joint,  which  it  completely 
protects  upon  its  inner  side.  Its  action  is  to  rotate  the  humerus 
inwards,  and,  when  the  arm  is  raised,  draws  it  downwards.  The 
nerves  which  supply  it  come  from  the  long  and  middle  subscapular 
nerves. 

The  coracoid  process,  with  the  coraco-brachialis  and  short  head 
of  the  biceps,  forms  an  arch,  under  which  the  tendon  of  the  sub- 


384 


ARTERIES    OF   THE   SCAPULA. 


scapularis  plays.  There  are  several  bursce  about  the  tendon.  Oner 
of  considerable  size,  on  the  upper  surface  of  the  tendon,  facilitates 
its  motion  beneath  the  coracoid  process  and  the  coraco-brachialis  : 
this  sometimes  communicates  with  the  large  bursa  under  the  del- 
toid. Another  is  situated  between  the  tendon  and  the  capsule  of 
the  joint,  and  almost  invariably  communicates  with  it. 


DIAGRAM    OF    ARTERIES    OF    SCAPULA. 


1.  Suprascapular  artery. 

2.  Posterior  circumflex  a. 

3.  Infraspinous  br.of  suprascapular  a. 


4.  Dorsalis  scapulas  a. 

5.  Posterior  scapular  a. 

6.  Subclavian  a. 


DISSECTION.  Now  reflect  the  muscles  from  the  surfaces  of  the 

scapula,  to  trace  the  arteries  which  ramify  upon  it. 

CONTINUATION  Tllis  artei7>  a  branch  of  the  thyroid  axis,  runs 

OF  SUPRASCAPU-  under  and  parallel  with  the  clavicle,  and  passes 
LAR  ARTERY  AND  above,  the  notch  of  the  scapula,  into  the  supra- 
spinous  fossa;  it  sends  a  branch  to  the  supra- 


NERVE. 


TRICEPS.  385 

spinatus,  another  to  the  shoulder-joint,  and  then  descends  behind 
the  neck  of  the  scapula  into  the  fossa  below  the  spine,  where 
it  inosculates  directly  with  the  dorsalis  scapulge.  Its  branches 
ramify  upon  the  bone,  and  supply  the  infraspinatus  and  teres 
minor  (fig.  88). 

The  suprascapular  nerve  passes  most  frequently  through  the 
notch  of  the  scapula,  accompanies  the  corresponding  artery,  sup- 
plies two  branches  to  the  supraspinatus  and  one  to  the  shoulder- 
joint  ;  it  then  enters  the  infraspinous  fossa,  to  terminate  in  the 
infraspinatus. 

DOKSALIS  This  artery,  after  passing  through  the  triangular 

SCAPTJUE  AKTEEY.  space  (p.  318),  curves  round  the  inferior  border  of 
the  scapula,  which  it  grooves,  to  the  infraspinous  fossa,  where  it 
ascends  close  to  the  bone,  and  anastomoses  with  the  supra-  and 
posterior  scapular  arteries.  Another  branch  of  the  subscapular 
artery  runs  between  the  teres  minor  and  major  towards  the  inferior 
angle  of  the  scapula,  where  it  anastomoses  with  the  posterior 
scapular  artery  (fig.  88). 

The  several  communications  about  the  scapula  between  the 
branches  of  the  subclavian  and  axillary  arteries  would  furnish  a 
large  collateral  supply  of  blood  to  the  arm,  if  the  subclavian  were 
tied  above  the  clavicle  (p.  122). 

If  the  skin  has  not  been  reflected  from  the  back 
of  the  arm,  it  should  now  be  done.  In  the  sub- 
cutaneous tissue  will  be  seen  the  internal  cutaneous  branch  of  the 
musculo-spiral  nerve,  which  supplies  the  skin  as  low  down  as  the 
olecranon.  On  the  inner  side  of  this  branch  is  the  intercosto- 
humeral  nerve,  supplying  the  skin  as  far  as  the  lower  third  of  the 
arm.  The  nerve  of  Wrisberg  also  supplies  the  lower  third  of  the 
arm ;  and  on  the  outer  side  for  the  same  distance  is  the  external 
cutaneous  branch  of  the  musculo-spiral  nerve. 

The  fascia  is  now  to  be  removed,  when  the  triceps  will  be 
exposed,,  forming  the  only  muscle  on  the  back  of  the  arm. 

TKICEPS  EXTEN-         This   muscle',   which    arises    by   three    distinct 
SOP.  CUBITI.  heads,  and  was  only  partially  seen  in  the  dissec- 

tion of  the  upper  arm  (p.  338),  should  now  be  thoroughly  ex- 
amined. The  long  head  arises  immediately  below  the  glenoid 

c  c 


386  TRICEPS. 

cavity  of  the  scapula,  by  a  strong  flat  tendon,  which  is  connected 
with  the  capsular  and  glenoid  ligaments  of  the  shoulder-joint. 
The  external  head  arises  from,  the  posterior  part  of  the  humerus, 
below  the  insertion  of  the  teres  minor,  as  far  as  the  musculo-spiral 
groove,  from  the  outer  border  of  the  humerus,  and  the  external 
intermuscular  septum.  The  internal  head  arises  from  the  posterior 
part  of  the  humerus,  below  the  teres  major  and  the  musculo-spiral 
groove,  as  far  as  the  olecranon  fossa ;  it  has  an  additional  origin 
from  the  internal  intermuscular  septum,  and  from  the  internal 
border  of  the  humerus.  The  precise  origin  of  these  heads  from 
the  humerus  may  be  ascertained  by  following  the  superior  profunda 
artery  and  musculo-spiral  nerve,  which  separate  them.  The  three 
portions  of  the  muscle  terminate  upon  a  broad  tendon,  which 
covers  the  back  of  the  elbow-joint,  and  is  inserted  into  the  summit 
and  sides  of  the  olecranon ;  it  is  also  connected  with  the  fascia  on 
the  back  cf  the  forearm.  The  effect  of  this  connection  is  that  the 
same  muscle  which  extends  the  forearm  tightens  the  fascia  which 
gives  origin  to  the  extensors  of  the  wrist  and  fingers.  The  same 
holds  good  in  the  case  of  the  biceps,  and  its  semilunar  expansion 
in  the  fascia  of  the  forearm. 

Between  the  tendon  and  the  olecranon  is  a  bursa,  commonly 
of  small  size,  but  sometimes  so  large  as  to  extend  upwards 
behind  the  capsule  of  the  joint.  This  bursa  must  not  be  mis- 
taken for  the  subcutaneous  one,  which  is  situated  between  the 
skin  and  the  olecranon,  and  is  so  often  injured  by  a  fall  on  the 
elbow. 

By   dividing   the   triceps   transversely  a  little 
DISSECTION. 

above  the  elbow,  and  turning  down   the   lower 

portion,  it  will  be  seen  that  some  of  the  muscular  fibres  terminate 
upon  the  capsular  ligament  of  the  joint.  They  have  been  described 
as  a  distinct  muscle,  under  the  name  of  the  subanconeus ;  their 
use  is  to  draw  up  the  capsule,  so  that  it  may  not  be  injured  during 
extension  of  the  arm.  The  subanconeus  is  in  this  respect  analo- 
gous to  the  subcrureus  muscle  of  the  thigh.  Observe  the  bursa 
under  the  tendon,  and  the  arterial  arch  formed  upon  the  back  part 
of  the  capsule  by  the  superior  profunda  and  the  anastomotica 
magna  (fig.  89,  p.  396). 


DISSECTION   OF   THE   BACK   OF  THE   FOREARM.  387 

Trace  the  continuation  of  the  superior  profunda  artery  (p.  333) 
and  musculo-spiral  nerve  round  the  posterior  part  of  the  humerus. 
They  lie  in  a  slight  groove  on  the  bone,1  between  the  external  and 
internal  heads  of  the  triceps,  and  are  protected  by  an  aponeurotic 
arch,  thrown  over  them  by  the  external  head  of  the  triceps.  After 
supplying  the  muscles,  the  artery  continues  its  course  along  the 
outer  side  of  the  arrn  between  the  brachialis  anticus  and  supinator 
radii  longus,  and  inosculates  with  the  radial  recurrent.  It  gives 
off  a  branch,  which  runs  down  between  the  triceps  and  the  bone, 
and  inosculates,  at  the  back  of  the  elbow,  with  the  anastomotica 
magna  and  posterior  interosseous  recurrent.  The  musculo-spiral 
nerve  which  accompanies  the  artery  sends  branches  to  supply  the 
three  portions  of  the  triceps,  the  supinator  radii  longus,  and  ex- 
tensor carpi  radialis  longior.2  It  then  divides  into  the  posterior 
interosseous  and  radial  nerves.  The  small  nerve  must  be  made  out 
which  runs  down  in  the  substance  of  the  triceps,  accompanied  by  a 
branch  from  the  superior  profunda  artery,  to  supply  the  anconeus. 
The  cutaneous  branches  of  the  musculo-spiral  nerve  have  been 
already  dissected  (p.  326). 


DISSECTION   OF   THE   BACK   OF   THE   FOEEAEM, 

SUBCUTANEOUS  Remove  the  skin  from  the  back  of  the  forearm, 

BUBS,E.  hand,  and  fingers,  and  make  out  the  subcutaneous 

bursa  over  the  olecranon.  It  is  of  considerable  size,  and,  if  dis- 
tended, would  appear  nearly  as  large  as  a  walnut.  Another  bursa 
is  sometimes  found  a  little  lower  down  upon  the  ulna.  A  sub- 
cutaneous bursa  is  generally  placed  over  the  internal  condyle, 
another  over  the  external.  A  bursa  is  also  situated  over  the  sty- 
loid  process  of  the  ulna;  this  sometimes  communicates  with  the 
sheath  of  the  extensor  carpi  ulnaris.  Small  bur  see  are  sometimes 
developed  in  the  cellular  tissue  over  each  of  the  knuckles. 

1  It  is  worth  remembering  that  the  nerve  may  be  injured  by  a  fracture  of  the 
humerus  in  this  situation,  and  even  by  too  tight  bandaging ;  the  result  being 
paralysis  of  the  extensor  muscles  of  the  forearm. 

2  The  brachialis  anticus  usually  receives  a  branch  from  the  musculo-spiral 
nerve. 

c  c  2 


o88  FASCIA   OX   THE   BACK   OF   THE   FOREARM. 

The  cutaneous  veins,  from  the  back  of  the  hand  and  forearm  r 
join  the  venous  plexus  at  the  bend  of  the  elbow  (see  p.  327). 

CUTANEOUS  ^^e  cutaneous  nerves  of  the  back  of  the  fore- 

NEEVES  OF  THE         arm,    are   derived    from    the    external    cutaneous 
BACK  OF  THE  branches  of  the  musculo-  spiral,  from  branches  of 

the  internal  cutaneous,  and  of  the  external  cuta- 
neous nerves.  The  greater  number  of  these  nerves  may  be  traced 
down  to  the  back  of  the  wrist. 

°n  ^6  ^aC^  °^  tne 


NEKVES  ON  THE 

BACK  OF  THE  the  subjacent  tendons  by  an  abundance  of  loose 

HAND  AND  connective  tissue,  in  which  are  large  veins,  and 

FINGERS.  branches  of  the  radial  and  ulnar  nerves.      The 

doi'sal  branch  of  the  ulnar  nerve  passes  beneath  the  tendon  of  the 
flexor  carpi  ulnaris,  pierces  the  fascia  just  above  the  wrist-joint, 
runs  over  the  posterior  annular  ligament  of  the  wrist,  and  divides 
upon  the  back  of  the  hand  into  filaments,  which  supply  both  sides 
of  the  back  of  the  little  finger,  the  ring  finger,  and  the  ulnar  side 
of  the  middle,  finger.  The  radial  nerve  passes  obliqitely  beneath 
the  tendon  of  the  supinator  longus,  perforates  the  fascia  about  two 
inches  above  the  wrist-joint,  and  subdivides  into  filaments,  which 
supply  both  sides  of  the  back  of  the  thumb  and  forefinger,  and  the 
radial  side  of  the  middle  finger.1 

The  radial  nerve  commonly  gives  off,  on  the  back  of  the  hand, 
a  branch  which  joins  the  nearest  branch  of  the  ulnar. 

FASCIA  ON  BACK  The  fascia  on  the  back  of  the  forearm  is  com- 

OF  FOREARM.  posed  of  fibres  interlacing  and  stronger  than  that 

upon  the  front  of  the  forearm.  It  is  attached  to  the  condyles  of 
the  humerus  and  to  the  olecranon,  and  is  strengthened  by  an 
expansion  from  the  tendon  of  the  triceps.  Along  the  forearm 
it  is  attached  to  the  ridge  on  the  posterior  part  of  the  ulna.  Its 
upper  third  gives  origin  to  the  fibres  of  the  muscles  beneath 

1  The  relative  share  which  the  radial  and  ulnar  nerves  take  in  supplying  the 
fingers  varies.  Under  any  arrangement  the  thumb  and  each  finger  has  two  dorsal 
nerves,  one  on  either  side,  of  which  the  terminal  branches  reach  the  root  of  the 
nail.  They  supply  filaments  to  the  skin  on  the  back  of  the  finger,  and  have  fre- 
quent communications  with  the  palmar  digital  nerves.  In  some  instances  one  or 
more  of  the  dorsal  nerves  do  not  extend  beyond  the  first  phalanx  :  their  place  is 
then  supplied  by  a  branch  from  the  palmar  nerve. 


SHEATHS  FOR  THE  EXTENSOR  TENDONS.          389 

it,  and  divides  them  by  septa,  to  which  their  fibres  are  also 
attached. 

POSTERIOR  This  ligament  should  be  considered  as  a  part  of 

ANNULAR  LIGA-  the  fascia  of  the  forearm,  specially  strengthened 
MENT>  by  oblique  aponeurotic  fibres  on  the  back  of  the 

wrist,  to  confine  the  extensor  tendons.  These  fibres  are  attached 
to  the  outer  margin  of  the  radius,  and  thence  pass  obliquely  in- 
wards to  the  inner  side  of  the  wrist,  where  they  are  connected 
with  the  pisiform  and  cuneiform  bones.  They  pass  below  the 
styloid  process  of  the  ulna,  to  which  they  are  in  no  way  attached, 
otherwise  the  rotation  of  the  radius  would  be  impeded. 

SEPARATE  From  the  deep  surface  of  the  posterior  annular 

SHEATHS  FOR  ligament,  processes  are  attached  to  the  ridges  on 

EXTENSOR  the  back  of  the  radius,  so  as  to  form  six  distinct 

fibro-osseous  sheaths  for  the  passage  of  the  ex- 
tensor tendons.  Commencing  from  the  radius,  the  first  sheath 
contains  the  tendons  of  the  extensor  ossis  metacarpi  and  the 
extensor  primi  internodii  pollicis  ;  the  second,  the  tendons  of  the 
extensor  carpi  radialis  longior  and  brevior  ;  the  third,  the  tendon 
of  the  extensor  secundi  internodii  pollicis  ;  the  fourth,  the  tendons 
of  the  extensor  indicis  and  the  extensor  communis  digitorum  ;  the 
fifth,  the  tendon  of  the  extensor  minimi  digiti ;  and  the  sixth,  the 
tendon  of  the  extensor  carpi  ulnaris.  All  the  sheaths  are  lined  by 
synovial  membranes,  which  extend  nearly  to  the  insertions  of  their 
tendons.  Occasionally,  but  not  often,  one  or  more  of  them  com- 
municate with  the  wrist-joint. 

The  fascia  of  the  metacarpus  consists  of  a  thin  fibrous  layer, 
continued  from  the  posterior  annular  ligament.  It  separates  the 
extensor  tendons  from  the  subcutaneous  veins  and  nerves,  and  is 
attached  to  the  radial  side  of  the  second  metacarpal  bone,  and  the 
ulnar  side  of  the  fifth. 

The  fascia  must  be  removed  from  the  muscles, 
without  injuring  the  muscular  fibres  which  arise 
from  its  under  surface.  Preserve  the  posterior  annular  ligament. 
The  following  superficial  muscles  are  now  exposed,  and  should  be 
examined  in  the  order  in  which  they  are  placed,  proceeding  from 
the  radial  to  the  ulnar  side: — 1.  The  supinator  radii  longus 


390   SUPERFICIAL  MUSCLES  ON  THE  BACK  OF  THE  FOREARM. 

SUPERFICIAL          (already  described,  p.  345).     2.  The  extensor  carpi 
MUSCLES  ON  THE       radialis   longior.     3.  The  extensor  carpi   radialis 

BACK  OF  THE  brevior.     4.  The    extensor   communis   digfitorum. 

ff 

5.  The  extensor  minimi  digiti.     6.  The  extensor 

carpi  ulnaris.     7.  The  anconeus. 

A  little  below  the  middle  of  the  forearm,  the  extensors  of  the 
wrist  and  fingers  diverge  from  each  other,  leaving  an  interval,  in 
which  are  seen  the  three  extensors  of  the  thumb — namely,  the  ex- 
tensor ossis  metacarpi  pollicis,  the  extensor  primi  internodii  pollicis, 
and  the  extensor  secundi  internodii  pollicis.  The  two  former  cross 
obliquely  over  the  radial  extensors  of  the  wrist,  and  pass  over  the 
lower  third  of  the  rad.ius ;  the  latter  emerges  from  under  the  radial 
border  of  the  extensor  communis  digitorum,  and  then  passes  over 
the  insertions  of  the  tendons  of  the  radial  extensors  of  the  wrist. 

Between  the  second  and  third  extensors  of  the  thumb,  we 
observe  a  part  of  the  lower  end  of  the  radius,  which  is  not  covered 
either  by  muscle  or  tendon.  This  subcutaneous  portion  of  the 
bone  is  immediately  above  the  prominent  tubercle  in  the  middle 
of  its  lower  extremity,  and,  since  it  can  be  easily  felt  through  the 
skin,  it  presents  a  convenient  place  for  examination  in  doubtful 
cases  of  fracture. 

EXTENSOR  This  muscle  is  partly  covered  by  the  supinator 

CARPI  KADIALIS  radii  longus.  It  arises  from  the  lower  third  of 
LONGIOR.  fae  r^ge  leading  to  the  external  condyle  of  the 

humerus,  and  from  the  intermuscular  septum.  It  descends  along 
the  outer  side  of  the  forearm,  and  terminates  'about  the  middle,  in 
a  flat  tendon,  which  passes  beneath  the  extensor  ossis  metacarpi 
and  primi  internodii  pollicis,  traverses  a  groove  on  the  outer  and 
back  part  of  the  radius,  lined  by  a  synovial  membrane,  and  is 
inserted  into  the  radial  side  of  the  carpal  end  of  the  metacarpal 
bone  of  the  index  finger.  Previous  to  its  insertion,  the  tendon  is 
crossed  by  the  extensor  secundi  internodii  pollicis.  It  is  supplied 
by  a  branch  from  the  musculo-spiral  nerve. 

EXTENSOR  This   muscle  arises  from  the   external  condyle 

CARPI  EADIALIS  by  the  tendon  common  to  it  and  the  other  ex- 
BREVIOR.  tensors,  from  the  intermuscular  septa,  from  the 

external  lateral  ligament  of  the  elbow-joint  and  the  aponeurosis 


EXTENSOR   COMMUNIS    DIGITORUM.  391 

covering  the  muscle.  The  muscular  fibres  terminate  near  the 
lower  third  of  the  forearm,  upon  the  under  surface  of  a  flat  tendon, 
which  descends,  covered  by  that  of  the  extensor  carpi  radialis 
longior,  beneath  the  three  extensors  of  the  thumb.  The  tendon 
traverses  a  groove  on  the  back  of  the  radius,  on  the  same  plane 
with  that  of  the  long  radial  extensor,  but  lined  by  a  separate 
synovial  membrane,  and  is  inserted  into  the  radial  side  of  the  base 
of  the  metacarpal  bone  of  the  middle  finger.  A  bursa  is  generally 
found  between  the  tendon  and  the  bone.  Its  nerve  comes  from  the 
posterior  interosseous. 

EXTENSOB  This   muscle  arises  from   the  common  tendon 

DIGITORUM  attached  to  the  external  condyle,  from  the  septa 

COMMDNIS.  between  it  and  the  contiguous  muscles,  and  from 

its  strong  fascial  covering.  A  little  below  the  middle  of  the  fore- 
arm, the  muscle  divides  into  three  tendons,  which  pass,  together 
with  the  extensor  indicis,  beneath  the  posterior  annular  ligament, 
through  a  groove  on  the  back  of  the  radius  lined  by  synovial 
membrane.  On  the  back  of  the  hand  the  tendons  become  broader 
and  flatter,  and  diverge  from  each  other  towards  the  metacarpal 
joints  of  the  fingers,  where  they  become  thicker  and  narrower, 
and  give  off,  on  each  side,  a  fibrous  expansion,  which  covers  the 
sides  of  the  joint.  Over  the  first  phalanx  of  the  finger,  each 
tendon  again  spreads  out,  receives  the  expanded  tendons  of  the 
lumbricales  and  interossei  muscles,  and  divides  at  the  second 
phalanx  into  three  portions,  of  which  the  middle  is  inserted  into 
the  upper  end  of  the  second  phalanx ;  the  two  lateral,  reuniting 
over  the  lower  end  of  the  second  phalanx,  are  inserted  into  the 
upper  end  of  the  third.1  Its  nerve  comes  from  the  posterior 
interosseous. 

The  oblique  aponeurotic  slips  which  connect  the  tendons  on 
the  back  of  the  hand  are  subject  to  great  variety.  The  tendon 
of  the  index  finger  is  commonly  free  ;  it  is  situated  on  the  radial 

1  The  extensor  tendons  are  inserted  into  the  periosteum ;  but  the  flexor  tendons 
are  inserted  into  the  substance  of  the  bone.  This  accounts  for  the  facility  with 
which  the  former  will  tear  off  the  bones  in  cases  of  necrosis,  while  the  latter  will 
adhere  so  tightly  as  to  require  cutting  before  the  phalanx  can  be  removed.  It  pro- 
bably also  explains  the  great  liability  to  necrosis  which  is  so  frequently  observed 
in  cases  of  thecal  abscess. 


392  EXTENSOR  CARPI   ULNARIS. 

side  of  the  proper  indicator  tendon,  and  becomes  united  with  it  at 
the  metacarpal  joint. 

The  tendon  of  the  middle  finger  usually  receives  a  slip  from 
that  of  the  ring.  The  tendon  of  the  ring  finger  generally  sends  a 
slip  to  the  tendons  on  either  side  of  it,  and,  in  some  cases,  entirely 
furnishes  the  tendon  of  the  little  finger.  Thus  the  ring  finger 
does  not  admit  of  independent  extension. 

The  muscle  is  not  only  a  general  extensor  of  the  fingers,  but 
can  extend  some  of  the  phalanges  independently  of  the  rest :  e.g. 
it  can  extend  the  first  phalanges  while  the  second  and  third  are 
flexed ;  or  it  can  extend  the  second  and  third  phalanges  during 
flexion  of  the  first. 

EXTENSOR  This  long  slender  muscle,  situated  on  the  ulnar 

MINIMI  DIGITI  OE  side  of  the  common  extensor,  arises  from  the  com- 
AUEICULAKIS.  mon  tendon  from  the  external  condyle,  and  from 

the  septa  between  it  and  the  contiguous  muscles.  Its  slender 
tendon  runs  separately  beneath  the  annular  ligament  immediately 
behind  the  joint  between  the  radius  and  ulna,  in  a  special  sheath 
lined  by  synovial  membrane.  On  emerging  from  the  annular  liga- 
ment, the  tendon  splits  into  two,  which  pass  obliquely  to  the  little 
finger.  At  the  first  joint  of  the  little  finger,  the  outer  tendon  is 
joined  by  that  of  the  common  extensor,  and  both  expand  upon  the 
first  and  second  phalanges,  terminating  in  the  same  manner  as  the 
extensor  tendons  of  the  other  fingers.  Its  nerve  comes  from  the 
posterior  interosseous. 

EXTENSOR  This   muscle  arises  from  the   common  tendon 

CARPI  ULNARIS.  from  the  external  condyle,  from  the  septum  be- 
tween it  and  the  extensor  minimi  digiti,  from  the  fascia  of  the 
forearm,  and  from  the  aponeurosis  attached  to  the  posterior  ridge 
of  the  ulna  common  to  this  muscle,  the  flexor  carpi  ulnaris,  and  the 
flexor  profundus  digitorum.  The  fibres  terminate  upon  a  strong, 
broad  tendon,  which  traverses  a  distinct  groove  on  the  back  of  the 
ulna,  close  to  the  styloid  process,  and  is  inserted  into  the  posterior 
aspect  of  the  carpal  end  of  the  metacarpal  bone  of  the  little  finger. 
Below  the  styloid  process  of  the  ulna,  the  tendon  passes  beneath 
the  posterior  annular  ligament,  over  the  back  of  the  wrist,  and  is 
confined  in  a  very  strong  fibrous  canal,  which  is  attached  to  the 


DEEP  MUSCLES  ON  THE  BACK  OF  THE  FOREARM.      393 

back  of  the  cuneiform,  pisiform,  and  unciform  bones,  and  is  lined 
by  a  continuation  from  the  synovial  membrane  in  the  groove  of  the 
ulna.  The  action  of  this  muscle  is  to  extend  the  hand,  and  incline 
it  towards  the  ulnar  side.  It  is  supplied  by  the  posterior  inter- 
osseous  nerve. 

In  pronation  of  the  forearm,  the  lower  articular  end  of  the  ulna 
projects  between  the  tendons  of  the  extensor  carpi  ulnaris  and  the 
extensor  minimi  digiti.  A  subcutaneous  bursa  is  sometimes  found 
-above  the  bone  in  this  situation. 

This  small  triangular  muscle  is  situated  at  the 
outer  and  back  part  of  the  elbow.  It  is  covered 
by  a  strong  layer  of  fascia,  derived  from  the  tendon  of  the  triceps, 
and  appears  like  a  continuation  of  that  muscle.  It  arises  by  a  ten- 
don from  the  posterior  part  of  the  external  condyle  of  the  humerus, 
and  is  inserted  into  the  triangular  surface  on  the  upper  fourth  of 
the  outer  part  of  the  ulna.  Part  of  the  under  surface  of  the  muscle 
is  in  contact  with  the  capsule  of  the  elbow-joint.  Its  action  is  to 
assist  in  extending  the  forearm.  Its  nerve  comes  from  the  musculo- 
spiral. 

To  expose  the  deep  layer  of  muscles,  detach  from 
DISSECTION.  ^,  ,  -11,1  •        j-  v 

the  external  condyie  the  extensor  carpi  radians 

brevior,  the  extensor  communis  digitorum,  the  extensor  minimi 
digiti,  and  the  extensor  carpi  ulnaris ;  and,  after  noticing  the  ves- 
sels and  nerves  which  enter  their  under  surface,  turn  them  down. 
The  deep-seated  muscles,  with  the  posterior  interosseous  artery  and 
nerve,  must  be  dissected.  The  muscles  exposed  are: — 1.  The  ex- 

DEEP  SEATED  tensor  ossis  metacarpi  pollicis.  2.  Extensor  primi 
MUSCLES  ON  THE  internodii  pollicis.  3.  Extensor  secundi  inter- 
BACK  OF  THE  nodii  pollicis.  4.  Extensor  indicis  or  indicator. 

POREAKM.  5  The  supinator  ra(jii  brevis.  They  are  all  sup- 

plied by  branches  from  the  posterior  interosseous  nerve. 

EXTENSOR  This  muscle  lies  immediately  below  the  supinator 

Ossis  METACARPI  brevis,  and  ayises  from  the  posterior  surface  of  the 
POLLICIS.  ulna  below  the  supinator  brevis,  from  the  posterior 

surface  of  the  middle  third  of  the  radius,  and  from  the  interosseous 
membrane.  The  muscle  passes  obliquely  downwards  and  outwards, 
crosses  the  radial  extensors  of  the  wrist  about  three  inches  above 


394  EXTENSORS    OF   THE   THUMB. 

the  carpus,  and  terminates  in  a  tendon,  which  passes  along  a 
common  groove  with  the  extensor  primi  internodii  pollicis,  lined 
by  synovial  membrane,  on  the  outer  part  of  the  lower  end  of 
the  radius,  and  is  inserted  into  the  base  of  the  metacarpal  bone 
of  the  thumb,  and  frequently  also  by  a  tendinous  slip  into  the 
trapezium. 

EXTENSOR  This,  the  smallest  of  the   deep  muscles,  arises 

PKIMI  INTERNODII  from  the  posterior  surface  of  the  radius,  below  the 
POLLICIS.  preceding,  and  from  the  interosseous  membrane. 

It  descends  obliquely  in  company  with  the  preceding  muscle,  turns 
over  the  radial  extensors  of  the  wrist,  and  terminates  upon  a  tendon 
which  passes  beneath  the  annular  ligament,  through  the  groove  on 
the  outer  part  of  the  radius,  and  is  inserted  into  the  radial  side  of 
the  base  of  the  first  phalanx  of  the  thumb. 

EXTENSOR  This  muscle   covers  part  of  the  origin  of  the 

SECUNDI  INTER-  preceding  muscle,  and  arises  from  the  posterior 
NODII  POLLICIS.  surface  of  the  ulna,  below  the  extensor  ossis  meta- 
carpi  pollicis,  and  from  the  interosseous  membrane.  The  tendon 
receives  fleshy  fibres  as  low  as  the  wrist,  passes  beneath  the  annu- 
lar ligament  in  a  distinct  groove  on  the  back  of  the  radius,  crosses 
the  tendons  of  the  radial  extensors  of  the  wrist,  proceeds  over  the 
metacarpal  bone  and  the  first  phalanx  of  the  thumb,  and  is  inserted 
into  the  base  of  the  last  phalanx. 

The  tendons  of  the  three  extensors  of  the  thumb  may  be  easily 
distinguished  in  one's  own  hand.  The  extensor  ossis  metacarpi 
and  primi  internodii  pollicis  cross  obliquely  over  the  radial  artery, 
where  it  lies  on  the  external  lateral  ligament  of  the  carpus ;  the 
extensor  secundi  internodii  pollicis  crosses  the  artery  just  before  it 
sinks  into  the  palm,  between  the  first  and  second  metacarpal  bones, 
and  is  a  good  guide  to  the  vessel.  The  action  of  the  three  extensors 
of  the  thumb  is  implied  by  their  names. 

EXTENSOR  This  muscle  arises  from  the  posterior  surface  of 

INDICIS,  OK  INDI-  the  ulna,  below  the  extensor  secundi  internodii 
CATOB-  pollicis,  and  slightly  from  the  interosseous  mem- 

brane. The  tendon  passes  beneath  the  posterior  annular  ligament, 
in  the  same  groove,  on  the  back  of  the  radius,  with  the  tendons  of 
the  extensor  digitorum  communis.  It  then  proceeds  over  the  back 


POSTERIOR  INTEROSSEOUS   ARTERY.  395 

of  the  haad  to  the  first  phalanx  of  the  index  finger,  where  it  is 
united  to  the  ulnar  border  of  the  common  extensor  tendon.  By 
the  action  of  this  muscle  the  index  finger  can  be  extended  indepen- 
dently of  the  others. 

Reflect  the  anconeus  from  its  origin,  to  expose 
DISSECTION.  , ,      „  ,,       .  n 

the  following  muscle — 

SUPINATOR  This  muscle  embraces  the  upper  third  of  the 

EADH  BKEVIS.  radius.  It  arises  from  the  external  condyle  of  the 

humerus,  from  the  external  lateral  ligament  of  the  elbow-joint, 
from  the  orbicular  ligament  surrounding  the  head  of  the  radius, 
from  an  oblique  ridge  on  the  outer  surface  of  the  ulna  below  the 
insertion  of  the  anconeus,  by  fleshy  fibres  from  the  triangular  ex- 
cavation below  the  lesser  sigmoid  notch  of  the  ulna,  and  from  the 
aponeurosis  covering  the  muscle.  The  muscular  fibres  tarn  over 
the  neck  and  upper  part  of  the  shaft  of  the  radius,  and  are  inserted 
into  the  upper  third  of  this  bone,  as  far  forwards  as  the  ridge  lead- 
ing from  the  tubercle  to  the  insertion  of  the  pronator  teres.  The 
muscle  is  traversed  obliquely  by  the  posterior  interosseous  nerve, 
which  sends  a  branch  to  it,  and  its  upper  part  is  in  contact  with 
the  capsule  of  the  elbow-joint.  It  is  a  powerful  supinator  of  -the 
forearm,  some  of  its  fibres  acting  at  nearly  a  right  angle  to  the 
axis  of  the  radius. 

POSTERIOR  This  artery  comes  from  the  ulnar  by  a  common 

INTEHOSSEOUS  trunk  with  the  anterior  interosseous  (p.  352),  and 

ARTERY.  supplies  the  muscles  on  the  back  of  the  forearm. 

It  passes  between  the  oblique  ligament  and  the  interosseous 
membrane,  and  appears,  at  the  back,  between  the  supinator  radii 
brevis  and  the  extensor  ossis  metacarpi  pollicis.  After  supplying 
branches  to  all  the  muscles  in  this  situation,  the  artery  descends, 
much  diminished  in  size,  between  the  superficial  and  deep  layer  of 
muscles  to  the  wrist,  where  it  inosculates  with  the  carpal  branches 
of  the  anterior  interosseous,  and  the  posterior  carpal  branches  of 
the  radial  and  ulnar  arteries. 

The  largest  branch  of  this  artery  is  the  interosseoiis  recurrent.  It 
ascends  beneath  the  supinator  brevis  and  the  anconeus  to  the  space 
between  the  external  condyle  and  the  olecranon,  where  it  inosculates 
with  the  branch  of  the  superior  profuiida  which  descends  in  the  sub- 


396 


POSTERIOR    IXTEROSSEOUS   NERVE. 


stance  of  the  triceps,  with  the  posterior  ulnar  recurrent  artery,  and 
with  the  anastomotica  magna. 

In  the  lower  part  of  the  back  of  the  forearm,  a  branch  of  the 
anterior  interosseous  artery  is  seen  passing  through  the  inter- 
osseous  membrane  to  reach  the  back  of  the  wrist. 

FIG.  89. 


1.  The  superior  profunda. 

2.  The  anastomotica  magna. 

3.  The  posterior  ulnar  recur- 

rent. 


4.  The  posterior  I 
interosseous 


I  its  ascending 
and  descend- 
ing branches. 

5.  The  termination  of  the  an- 

terior interosseous. 

6.  The  posterior  carpal  arch. 


DIAGKAM    SHOWING    THE    ANASTOMOSES    OF    ABTEKIES   AT    THE    BACK    OF    THE    ELBOW 
AND    WBIST    JOINTS. 


POSTEBIOB 
INTEBOSSEOUS 
NEBVE. 


The  nerve  which  supplies  the  muscles  on  the 
back  of  the  forearm  is  the  posterior  interosseous, 
one  of  the  divisions  of  the  musculo-spiral.  It 
passes  obliquely  through  the  supinator  radii  brevis,  and  descends, 
lying  on  the  lower  fibres  of  this  muscle,  the  extensores  ossis  meta- 
carpi  and  primi  internodii  pollicis,  and  beneath  the  superficial 
extensors.  It  then,  much  diminished  in  size,  passes  under  the 


RADIAL    ARTERY   ON   THE    BACK    OF   THE    WRIST.  397 

extensor  secundi  internodii  pollicis,  on  the  interosseous  membrane, 
as  far  as  the  posterior  annular  ligament,  where  it  presents  a  gan- 
giiform  enlargement.  Between  the  superficial  and  deep  layer  of 
muscles,  it  sends  to  each  a  filament,  generally  in  company  with  a 
branch  of  the  posterior  interosseous  artery.  It  sends  a  branch  to 
the  extensor  carpi  radialis  brevior,  and  supplies  the  supinator  brevis 
in  passing  through  its  substance.  The  supinator  radii  longus  and 
the  extensor  carpi  radialis  longior  are  supplied  by  distinct  branches 
from  the  musculo-spiral  nerve. 

After  the  posterior  interosseous  nerve  descends  beneath  the 
extensor  secundi  internodii  pollieis,  it  lies  in  the  interosseous 
membrane,  beneath  the  extensor  digitorum  communis  and  the 
indicator.  At  the  back  of  the  wrist,  beneath  the  annular  ligament, 
it  forms  the  gangliform  enlargement  from  which  filaments  are  sent 
to  the  carpal  and  metacarpal  joints. 

DISSECTION  ^e  ™dial  artery  is  continued  over  the  external 

RADIAL  AETEKY  lateral  ligament  of  the  carpus,  beneath  some  fila- 
ON  THE  BACK  OF  ments  of  the  radial  nerve,  cutaneous  veins,  and 
THEWKIST.  ^e  extensor  tendons  of  the  thumb,  to  the 

proximal  part  of  the  interval  between  the  first  and  second  meta- 
carpal bones,  where  it  dips  down  between  the  two  origins  of  the 
abductor  indicis,  and,  entering  the  palm,  forms  the  deep  palmar 
arch.  In  this  part  of  its  course  it  is  accompanied  by  a  filament  of 
the  musculo-cutaneous  nerve ;  observe  also  that  the  tendon  of  the 
extensor  secundi  internodii  pollicis  passes  over  it  immediately 
before  it  sinks  into  the  palm.  It  supplies  in  this  part  of  its  course 
the  following  small  branches  to  the  back  of  the  hand  : — 

a.  Posterior  carpal  artery. — This  branch   passes   across  the  carpal 
bones,  beneath  the  extensor  tendons.     It  inosculates  with  the  termina- 
tion of  the  anterior  interosseous  artery,  and  forms  an.  arch  beneath  the 
extensor  tendons,  with  a  corresponding  branch  from  the  ulnar  artery. 
The  carpal  arch  sends  off  small  branches,  called  the  dorsal  interosseous, 
which  descend  along  the  third  and  fourth  interosseous  spaces  from  the 
arch  just  mentioned,  beneath  the  extensor  tendons,  and  inosculate  near 
the  carpal  ends  of  the  metacarpal  bones  with  the  perforating  branches 
from  the  deep  palmar  arch. 

b.  The  first  dorsal  interosseous  artery  is  generally  larger  than  the 


•398  INTEROSSEOUS  MUSCLES. 

others.  It  passes  forwards,  beneath  the  extensors  of  the  thumb,  on  the 
second  interosseous  space  to  the  cleft  between  the  index  and  middle 
fingers,  communicating  here  with  a  perforating  branch  of  the  deep 
palmar  arch  ;  and  terminates  in  small  branches,  some  of  which  proceed 
along  the  back  of  the  fingers,  others  inosculate  with  the  palmar  digital 
arteries. 

c.  The  dorsalis  indicis,   a  branch  of  variable  size,  passes  over  the 
first  interosseous  muscle  along  the  radial  side  of  the  back  of  the  index 
finger. 

d.  The  dorsales  pollicis  are  two  small  branches  which  arise  from  the 
radial  opposite  the  head  of  the  first  metacarpal  bone,  and  run  along  the 
back  of  the  thumb,  one  on  either  side.     They  are  often  absent. 

These  dorsal  interosseous  arteries  supply  the  extensor  tendons  and 
their  sheaths,  the  interosseous  muscles,  and  the  skin  on  the  back  of  the 
hand,  and  the  first  phalanges  of  the  fingers. 

Remove  the  tendons  from  the  back,  and  from 
the  palm,  of  the  hand :  observe  the  deep  palmar 
fa'scia  which  covers  the  interosseous  muscles.  It  is  attached  to 
the  ridges  of  the  metacarpal  bones,  forms  a  distinct  sheath  for 
each  interosseous  muscle,  and  is  continuous  inferiorly  with  the 
transverse  metacarpal  ligament.  On  'the  back  of  the  hand  the 
interosseous  muscles  are  covered  by  a  thin  fascia,  which  is  attached 
to  the  adjacent  borders  of  the  metacarpal  bones. 

TEANSVEKSE  This   consists  of  strong  bands  of  ligamentons 

METACAEPAL  fibres,  which  pass  transversely  between  the  distal 

LIGAMENT.  extremities  of  the  metacarpal  bones.     These  bands 

are  intimately  united  to  the  fibre-cartilaginous  ligament  of  the 
metacarpal  joints,  and  are  of  sufficient  length  to  admit  of  a  certain 
degree  of  movement  between  the  ends  of  the  metacarpal  bones. 

Remove  the  fascia  which  covers  the  interosseous 
DISSECTION.  ,  -,  ,      ,-,  111 

muscles,  and  separate  the  metacarpal    bones    by 

dividing  the  transverse  metacarpal  ligament.  A  bursa  is  fre- 
quently developed  between  their  digital  extremities. 

INTEKOSSEOUS  These  muscles,  so  named  from  their  position, 

MUSCLES.  extend  from  the  sides  of  the  metacarpal  bones  to 

the  bases  of  the  first  phalanges  and  the  extensor  tendons  of  the 
fingers.  In  each  interosseous  space  (except  the  first,  in  which 


DORSAL   INTEROSSEI. 


399 


there  is  only  an  abductor)  there  are  two  muscles,  one  of  which  is 
an  abductor,  the  other  an  adductor,  of  a  finger.  Thus  there  are 
.seven  in  all :  four  of  which,  situated  on  the  back  of  the  hand,  are 
called  dorsal ;  the  remainder,  seen  only  in  the  palm,  are  called 
palmar.1  They  are  all  supplied  by  the  ulnar  nerve. 

DORSAL  Each    dorsal    interosseous    is    a    bipenniform 

INTEROSSEI.  muscle,  and  arises  from  the  opposite  sides  of  two 

contiguous  metacarpal  bones  (fig.  90).  From  this  double  origin 
the  fibres  converge  to  a  tendon,  which  passes  between  the  meta- 


FIG.  90. 


FIG.  91. 


DIAGRAM  OF  THE  FOUR  DORSAL  IN- 
TEROSSEI, DRAWING  FROM  THE 
MIDDLE  LINE. 


DIAGRAM  OF  THE  THREE  PALMAR  INTER- 
OSSEI, AND  THE  ADDUCTOR  POLLICIS, 
DRAWING  TOWARDS  THE  MIDDLE  LINE. 


carpal  joints  of  the  finger,  and  is  inserted  into  the  side  of  the  base 
of  the  first  phalanx,  and  by  a  broad  expansion  into  the  extensor 
tendon  on  the  back  of  the  same  finger. 

The  first  dorsal  interosseous  muscle  (abductor  indicis)  is  larger 
than  the  others,  and  occupies  the  interval  between  the  thumb  and 
fore-finger.  It  arises  from  the  proximal  half  of  the  ulnar  side  of 
the  first  metacarpal  bone,  and  from  the  entire  length  of  the  radial 
side  of  the  second  :  between  the  two  origins,  the  radial  artery 

1  If  we  consider  the  adductor  pollicis  as  a  palmar  interosseous  muscle,  there 
would  be  four  palmar  and  four  dorsal — all  supplied  by  the  ulnar  nerve. 


400  PALMAR  INTEROSSEI. 

passes  into  the  palm.  Its  fibres  converge  on  either  side  to  a 
tendon,  which  is  inserted  into  the  radial  side  of  the  first  phalanx 
of  the  index  finger  and  its  extensor  tendon. 

The  second  dorsal  interosseous  muscle  occupies  the  second  meta- 
carpal  space.  It  is  inserted  into  the  radial  side  of  the  first  phalanx 
of  the  middle  finger  and  its  extensor  tendon. 

The  third  and  fourth,  occupying  the  corresponding  metacarpal 
spaces,  are  inserted,  the  one  into  the  ulnar  side  of  the  middle,  the 
other  into  the  ulnar  side  of  the  ring  finger. 

If  a  line  be  drawn  longitudinally  through  the  middle  finger,  as 
represented  by  the  dotted  line  in  fig.  90,  we  find  that  all  the 
dorsal  interosseous  muscles  are  abductors  from  that  line ;  conse- 
quently, they  separate  the  fingers  from  each  other. 

PALMAR  INTER-  It  requires  a  careful  examination  to  distinguish 

OSSEOUS.  this  set  of  muscles,   because  the  dorsal  muscles 

protrude  with  them  into  the  palm.  They  are  smaller  than  the 
dorsal,  and  each  arises  from  the  lateral  surface  of  only  one  meta- 
carpal bone — that,  namely,  connected  with  the  finger  into  which 
the  muscle  is  inserted  (fig.  91).  They  terminate  in  small 
tendons,  which  pass  between  the  metacarpal  joints  of  the  fingers, 
and  are  inserted,  like  those  of  the  dorsal  muscles,  into  the  sides  of 
the  first  phalanges  and  the  extensor  tendons  on  the  back  of  the 
fingers. 

The  first  palmar  interosseous  muscle  arises  from  the  ulnar  side 
of  the  second  metacarpal  bone,  and  is  inserted  into  the  ulnar  side 
of  the  index  finger.  The  second  and  third  arise,  the  one  from  the 
radial  side  of  the  fourth,  the  other  from  the  radial  side  of  the  fifth 
metacarpal'  bone,  and  are  inserted  into  the  same  sides  of  the  ring 
and  little  fingers. 

The  palmar  interosseous  muscles  are  all  adductors  to  a  line 
drawn  through  the  middle  finger  (fig.  91).  They  are,  therefore, 
the  opponents  of  the  dorsal  interosseous,  and  move  the  fingers 
towards  each  other.1  . 

1  The  interossei,  probably,  also  assist  the  flexors  of  the  ringers  when  the  latter 
are  slightly  flexed  at  their  metacarpo-phalangeal  joints.  M.  Duchenne  believes 
that,  in  addition  to  their  usually  ascribed  function  of  abduction,  adduction,  and 
supplemental  flexion  at  the  nietaearpo-phalangeal  articulation,  the  interossei  act 


STERNO-CLAVICULAR   LIGAMENTS.  401 

The  palmar  and  dorsal  interossei  are  supplied  by  filaments  from 
the  deep  branch  of  the  ulnar  nerve. 


DISSECTION  OF  THE   LIGAMENTS. 

STEENO-CLAVI-  The  inner  end  of  the  clavicle  articulates  with 

CUIAB  JOINT.  the  comparatively  small  and  shallow  excavation 

on  the  upper  and  outer  part  of  the  sternum,  and  is  an  arthrodial 
joint.  The  security  of  the  joint  depends  upon  the  great  strength 
of  its  ligaments.  There  are  two  synovial  membranes,  and  an 
intervening  fibre-cartilage. 

The  anterior  sterno-clavicular  ligament  (fig.  92)  consists  of  a 
strong  broad  band  of  ligamentous  fibres,  which  pass  obliquely 
downwards  and  inwards  over  the  front  of  the  joint,  from  the 
inner  end  of  the  clavicle  to  the  anterior  surface  of  the  sternum. 

The  posterior  sterno-clavicular  ligament  extends  over  the  back 
of  the  joint,  its  fibres  passing  downwards  and  forwards  from  the 
back  of  the  clavicle  to  the  back  of  the  sternum  in  a  similar  manner 
to  the  anterior. 

The  interclavicular  ligament  connects  the  clavicles  directly. 
It  extends  transversely  along  the  notch  of  the  sternum,  and  has  a 
broad  attachment  to  the  upper  border  of  each  clavicle.  Between 
the  clavicles  it  is  more  or  less  attached  to  the  sternum,  so  that  it 
forms  a  curve  with  the  concavity  upwards. 

The  three   ligaments  just  described  are  so  closely  connected 

as  extensors  of  the  second  and  third  phalanges  ;  the  common  extensor  tendons 
acting  only  as  extensors  of  the  first  phalanges.  (Physiologie  des  Mouvements  <&c., 
1867.)  The  action  of  the  lumbricales  in  extending  the  second  and  third  phalanges 
(even  if  they  are  not  the  chief  factors  of  this  movement)  must  not  be  lost  sight  of, 
for  in  a  case,  recorded  in  St.  Barttiolomew' 's  Hospital  Reports,  1881,  in  which 
the  ulnar  nerve  had  been  divided  a  short  distance  above  the  wrist-joint,  the  first 
phalanges  of  the  ring  and  little  ringers  were  bent  (extended)  upon  their  articu- 
lating metacarpal  bones,  the  second  and  third  phalanges  being  flexed  at  obtuse 
angles  upon  their  proximal  phalanges  :  the  index  and  middle  fingers  being  normal. 
I  attribute  this  condition  to  paralysis  of  the  two  ulnar  lumbricales  and  not  to 
loss  of  power  of  the  interossei.  I  have  seen  about  a  dozen  instances  of  division 
of  the  ulnar  nerve,  and  in  all  of  them  the  same  condition  of  the  little  and  ring 
fingers  has  existed. 

D  D 


402 


STEENO-CLAVICULAR   LIGAMENTS. 


that,  collectively,  they  form  for  the  joint  a  complete  fibrous  capsule 
of  such  strength  that  dislocation  of  it  is  rare. 

The  costo-clavicular  or  rhomboid  ligament  connects  the  clavicle 
to  the  cartilage  of  the  first  rib.  It  ascends  obliquely  outwards  and 
backwards  from  the  cartilage  of  the  rib  to  a  rough  surface  beneath 
the  sternal  end  of  the  clavicle.  Its  use  is  to  limit  the  elevation  of 
the  clavicle.  There  is  such  constant  movement  between  the  clavicle 
and  the  cartilage  of  the  first  rib  that  a  well-marked  bursa  is  com- 
monly found  between  them. 

FIG.  92. 


DIAGRAM   OF   THE   STEBNO-CLAVICULAK   LIGAMENTS. 


1.  Interclavicular  ligament. 

2.  Anterior  sterno-clavicular  ligament. 


3.  Costo-clavicular  ligament. 

4.  Interarticular  fibro-cartilage. 


Interarticular  fibro-cartilage.  —  To  see  this,  cut  through  the 
rhomboid,  the  anterior  and  posterior  ligaments  of  the  joint,  and 
raise  the  clavicle.  It  is  nearly  circular  in  form,  and  thicker  at 
the  circumference  than  the  centre,  in  which  there  is  sometimes 
a  perforation,  and  divides  the  articulation  into  two  cavities.  In- 
feriorly,  it  is  attached  to  the  cartilage  of  the  first  rib,  close  to  the 
sternum ;  superiorly,  to  the  upper  part  of  the  clavicle  and  the 
inter  clavicular  ligament.  Its  circumference  is  inseparably  con- 
nected with  the  anterior  and  posterior  ligaments.1 

1  Interarticular  fibro-cartilages  (menisci)  also  exist  in  the  following  joints  : 
acromio-clavicular,  temporo-maxillary,  knee,  and  wrist  joints.  Professor  Hum- 
phry has  shown  that  interarticular  cartilages  augment  the  variety  of  movements 
in  a  joint,  permitting  for  instance  that  of  rotation  in  the  knee-joint,  in  addition  to 
that  of  extension  and  flexion,  which  otherwise  would  be  the  only  possible  ones. 


SCAPULO-CLAVICULAR   JOINT.  403 

The  joint  is  provided  with  two  synovial  membranes :  one  between 
the  articular  surface  of  the  sternum  and  the  inner  surface  of  the 
nbro-cartilage ;  the  other  between  the  articular  surface  of  the 
clavicle  and  the  outer  surface  of  the  nbro-cartilage. 

This  interarticular  nbro-cartilage  is  a  structure  highly  elastic, 
without  admitting  of  any  stretching.  It  equalises  pressure,  breaks 
shocks,  and  also  acts  as  a  ligament,  tending  to  prevent  the  clavicle 
from  being  driven  inwards  towards  the  mesial  line. 

Observe  the  relative  form  of  the  cartilaginous  surfaces  of  the 
bones :  that  of  the  sternum  is  slightly  concave  in  the  transverse, 
and  convex  in  the  antero-posterior  direction ;  that  of  the  clavicle 
is  the  reverse. 

The  form  of  the  articular  surfaces  and  the  ligaments  of  a  joint 
being  known,  it  is  easy  to  understand  the  movements  of  which  it 
is  capable.  The  clavicle  can  be  moved  upon  the  sternum  in  a 
direction  either  upwards,  downwards,  backwards,  and  forwards  ;  it 
also  admits  of  circumduction.  These  movements,  though  limited 
at  the  sternum,  are  considerable  at  the  apex  of  the  shoulder.1 

SOAPULO-  The  outer  end  of  the  clavicle  articulates  with 

«LAVICULAH  the    acromion,  and  is   connected  by  strong  liga- 

JOINT-  ments  to  the  coracoid  process  of  the  scapula. 

The  clavicle  and  the  acromion  articulate  with  each  other  by 
two  flat  oval  cartilaginous  surfaces,  of  which  the  planes  slant 
inwards,  and  the  longer  diameters  are  in  the  antero-posterior 
direction.  It  is  an  arthrodial  joint. 

The  superior  acromio-clavicular  ligament,  a  broad  band  of  par- 
allel ligamentous  fibres,  strengthened  by  the  aponeurosis  of  the 

1  Professor  Humphry,  in  describing  the  movements  of  this  joint,  in  his  valuable 
work  '  On  the  Human  Skeleton,'  says,  '  The  movements  attendant  on  elevation  and 
depression  of  the  shoulder  take  place  between  the  clavicle  and  the  interarticular 
ligament,  the  bone  rotating  upon  the  ligament  on  an  axis  drawn  from  before  back- 
wards through  its  own  articular  facet.  When  the  shoulder  is  moved  forwards  and 
backwards,  the  clavicle,  with  the  interarticular  ligament,  rolls  to  and  fro  on  the 
articular  surface  of  the  sternum,  revolving,  with  a  slightly  sliding  movement,  round 
an  axis  drawn  nearly  vertically  through  the  sternum.  In  the  circumduction  of  the 
shoulder,  which  is  compounded  of  these  two  movements,  the  clavicle  revolves  upon 
the  interarticular  cartilage,  and  the  latter,  with  the 'clavicle,  rolls  upon  the 
sternum.' 

n  n  2 


404  CONOID   AND   TRAPEZOID   LIGAMENTS. 

trapezius,  extends  from  the  upper  surface  of  the  acromion  to  the 
upper  surface  of  the  clavicle. 

The  inferior  acromio-clavicidar  ligament,  of  less  strength,  ex- 
tends along  the  under  surface  of  the  joint  from  bone  to  bone. 

An  interarticular  fibro-cartilac/e  is .  sometimes  found  in  this 
joint :  but  it  is  incomplete,  and  seldom  extends  lower  than  the 
upper  half.  There  is  only  one  synovial  membrane. 

Coraco-clavicidar  ligament. — The  clavicle  is  connected  to  the 
coracoid  process  of  the  scapula  by  two  strong  ligaments — the 
conoid  and  trapezoid,  which,  being  continuous  with  each  other, 
should  be  considered  as  one.  The  trapezoid  ligament  is  the  more 
anterior  and  external.  Quadrilateral  in  shape,  it  arises  from  the 


(portions  of  -. — T~  5.  Tendon  of  biceps. 
/;       -•:,    -^s^^m^i||ifc^gjg^ 

thecoraco-  W^^T  6<  CaPsular  ligament   of 

clavicular  ^.^jBF^"^^?  the  shoulder-joint, 

ligament.  ^H^^U^r^^.    ""Hj^" "  ~*""   7.  Coraco-humeral    liga- 

3.  Suprascapular  or  trans-  M^^-          I^KS^^  ment. 

verse  ligament.  ^        /^B  8.  Foramen  in  the  capsu- 

4.  Coraco-acromial     liga-  \r~~um^k        IE- 6  lar  ligament  for  the 

ment.  /*>  J|r//.^^^B  snbscapnlaris  tendon. 


ANTEEIOK    VIEW    OF    THE    SCAPULO-CLAVICULAE    LIGAMENTS,    AND    OF    THE 
SHOULDER-JOINT. 

back  of  the  upper  surface  of  the  coracoid  process,  and  ascends 
obliquely  backwards  and  outwards  to  the  oblique  line  on  the  under 
aspect  of  the  clavicle,  near  its  outer  end.  The  conoid  ligament, 
triangular  in  form,  is  situated  behind  the  trapezoid  ligament  to  the 
posterior  border  of  which  it  is  attached.  It  is  fixed  at  its  apex  to 
the  root  of  the  coracoid  process,  ascends  nearly  vertically,  and  is 
attached  by  its  base  to  the  clavicle.  The  coraco-clavicular  liga- 
ments fix  the  scapula  to  the  clavicle,  and  prevent  undue  rotation  of 
the  scapula.  When  the  clavicle  is  fractured  in  the  line  of  the 
attachment  of  the  coraco-clavicular  ligament,  there  is  little  or  no 
displacement  of  the  fractured  ends,  these  being  kept  in  place  by 
the  ligament. 


THE   SHOULDER-JOINT.  405 

LIGAMENTS  OF  These  are  two :  the  coraco-acromial  or  triangular 

THE  SCAPULA,  ligament,  attached  by  its  apex  to  the  tip  of  the 

acromion  process,  and  by  its  base  to  the  outer  border  of  the 
coracoid  process ;  it  is  separated  from  the  upper  part  of  the  capsule 
of  the  shoulder-joint  by  a  large  bursa  ;  and  the  transverse  or  cora- 
coid ligament,  which  passes  across  the  suprascapular  notch,  con- 
verting it  into  a  foramen.  The  suprascapular  vessels  pass  over 
the  foramen,  the  suprascapular  nerve  through  it. 

SHOULDER-  The  articular  surface  of  the  head  of  the  humerus, 

JOINT.  forming  rather  more  than  one-third  of  a  sphere, 

moves  upon  the  shallow  glenoid  cavity  of  the  scapula,  which  is  of  an 
oval  form,  with  the  broader  end  downwards,  and  the  long  diameter 
nearly  vertical.  The  security  of  the  joint  depends,  not  upon  any 
mechanical  contrivance  of  the  bones,  but  upon  the  great  strength 
and  number  of  the  ligaments  and  tendons  which  surround  and  are 
intimately  connected  with  it.  It  is  an  enarthrodial,  or  ball-and- 
socket  joint. 

To  admit  the  free  motion  of  the  head  of  the  humerus  upon  the 
glenoid  cavity,  it  is  requisite  that  the  capsular  ligament  of  the  joint 
be  loose  and  capacious.  Accordingly,  the  head  of  the  bone,  when 
detached  from  its  muscular  connections,  may  be  separated  from  the 
glenoid  cavity  to  the  extent  of  an  inch  or  more,  without  laceration 
of  the  capsule.  This  explains  the  elongation  of  the  arm  observed 
in  some  cases  in  which  effusion  takes  place  into  the  joint ;  also  in 
cases  of  paralysis  of  the  deltoid. 

The  capsular  ligament  is  attached  above,  round  the  circumference 
of  the  glenoid  cavity;  below,  round  the  anatomical  neck  of  the 
humerus.  It  is  strongest  on  its  upper  aspect,  weakest  and  long- 
est on  its  lower.  It  is  strengthened  on  its  upper  and  posterior 
part  by  the  tendons  of  the  supraspinatus,  infraspinatus,  and  teres 
minor  ;  its  inner  part  is  strengthened  by  the  broad  tendon  of  the 
subscapularis  and  the  coraco-humeral  ligament ;  its  lower  part,  by 
the  long  head  of  the  triceps. 

Thus  the  circumference  of  the  capsule  is  surrounded  by  tendons 
on  every  side,  excepting  a  small  space  towards  the  axilla.  If  the 
humerus  be  raised,  it  will  be  found  that  the  head  of  the  bone  rests 
upon  this  unprotected  portion  of  the  capsule,  between  the  tendons 


406  THE   SHOULDER- JOINT. 

of  the  subscapularis  and  the  long  head  of  the  triceps  :  through  this 
part  of  the  capsule  the  head  of  the  bone  is  first  protruded  in  dislo- 
cations into  the  axilla. 

At  the  upper  and  inner  side  of  the  joint,  a  small  opening  is 
observable  in  the  capsular  ligament,  through  which  the  tendon  of 
the  subscapularis  passes,  so  that  the  synovial  membrane  of  the  joint 
communicates  with  the  bursa  under  the  tendon  of  this  muscle.  A 
second  opening  exists  in  the  lower  part  of  the  front  of  the  capsular 
ligament,  where  the  tendon  of  the  biceps  emerges  from  the  joint. 
A  third  opening  occasionally  exists  between  the  joint,  and  a  bursa 
under  the  tendon  of  the  infraspinatus  muscle. 

The  upper  and  inner  surface  of  the  capsule  is  strengthened  by 
a  strong  band  of  ligamentous  fibres,  called  the  coraco-humeral  or 
accessory  ligament.  It  is  attached  to  the  root  of  the  coracoid  pro- 
cess, expands  over  the  upper  surface  of  the  capsule,  with  which  it 
is  inseparably  united,  and,  passing  downwards  and  outwards,  is 
attached  to  the  greater  tuberosity  of  the  humerus. 

Open  the  capsule  to  see  the  tendon  of  the  long  head  of  the  biceps. 
It  arises  by  a  rounded  tendon  from  the  upper  margin  of  the  glenoid 
cavity,  and  is  continuous  with  the  glenoid  ligament ;  becoming 
slightly  flattened,  it  passes  over  the  head  of  the  humerus,  descends 
through  the  groove  between  the  two  tuberosities,  and,  after  piercing 
the  capsular  ligament  of  the  shoulder-joint,  it  passes  along  the 
bicipital  groove,  being  retained  in  situ  by  an  aponeurotic  prolon- 
gation from  the  tendon  of  the  pectoralis  major.  It  is  loose  and 
moveable  within  the  joint.  It  acts  like  a  strap,  keeping  down 
the  head  of  the  bone  when  the  arm  is  raised  by  the  deltoid,  and 
then  might  be  considered  as  taking  the  part  of  a  ligament  of  the 
joint. 

The  tendon  of  the  biceps,  strictly  speaking,  does  not  perforate 
the  synovial  membrane  of  the  joint.  It  is  enclosed  in  a  tubular 
sheath,  which  is  reflected  over  it  at  its  attachment  to  the  glenoid 
cavity,  and  accompanies  it  for  two  inches  down  the  groove  of  the 
humerus.  During  the  earlier  part  of  foetal  life,  it  is  connected  to 
the  capsule  by  a  fold  of  synovial  membrane,  which  subsequently 
disappears. 

The  margin  of  the  glenoid  cavity  of  the  scapula  is  surrounded 


THE    SHOULDER-JOINT.  407 

by  a  fibre-cartilaginous  band  of  considerable  thickness,  called  the 
glenoid  ligament.  This  not  only  enlarges,  but  deepens  the  cavity. 
Superiorly,  it  is  continuous  on  either  side  with  the  tendon  of  the 
biceps ;  inferiorly,  with  the  tendon  of  the  triceps  :  in  the  rest  of 
its  circumference  it  is  attached  to  the  edge  of  the  cavity. 

The  cartilage  covering  the  head  of  the  humerus  is  thicker  at 
the  centre  than  at  the  circumference.  The  reverse  is  the  case  in 
the  glenoid  cavity. 

The  synovial  membrane  lining  the  under  surface  of  the  capsule, 
is  reflected  around  the  tendon  of  the  biceps,  and  passes  with  it  in 
the  form  of  a  cul-de-sac  down  the  bicipital  groove.  On  the  inner 
side  of  the  joint  it  always  communicates  with  the  bursa  beneath 
the  tendon  of  the  subscapularis. 

.  There  is  also  a  large  bursa  situated  between  the  capsule  and 
the  deltoid  muscle,  which  does  not  communicate  with  the  joint. 

The  muscles  in  relation  with  the  joint  are :  above,  the  supra- 
spinatus ;  behind,  the  infraspinatus  and  teres  minor ;  below,  the 
long  head  of  the  triceps ;  internally,  the  subscapularis  ;  and,  inside 
the  joint,  the  long  head  of  the  biceps. 

The  shoulder-joint  is  an  enarthrodial  joint,  and  has  a  more  ex- 
tensive range  of  motion  than  any  other  joint  in  the  body ;  it  is 
what  mechanics  call  a  universal  joint.  It  is  capable  of  motion 
forwards  and  backwards,  of  adduction,  abduction,  circumduction, 
and  rotation.  The  various  movements  are  limited  chiefly  by  the 
surrounding  muscles  and  by  atmospheric  pressure,  for  the  capsule 
is  so  lax  as  to  offer  no  obstacle  to  the  freedom  of  movement  in  any 
direction.  The  amount  of  rotation  which  the  head  of  the  humerus 
is  capable  of,  is  to  the  extent  of  a  quarter  of  a  circle. 

The  movements  of  which  the  shoulder-joint  is  capable  are 
effected  by  the  following  muscles  :  thus — 

Extension  is  effected  by  the  posterior  fibres  of  the  deltoid,  latis- 
simus  dorsi,  teres  major,  and  (when  the  arm  is  raised)  by  the  infra- 
spinatus and  teres  minor. 

Flexion,  by  the  anterior  fibres  of  the  deltoid,  coraco-brachialis, 
and  the  pectoralis  major  (slightly). 

Abduction,  by  the  deltoid  and  the  supraspinatus. 

Adduction,  by  the  pectoralis  major,  latissimus  dorsi,  teres  major, 


408 


THE   ELBOW-JOES'T. 


coraco-brachialis  ;   and    (when   the   arm   is   raised)  by  the   sub- 
scapular  is. 

Rotation  inwards,  by  the   subscapularis,  latissimus  dorsi,  and 
teres  major. 

Rotation  outivards,  by  the  infraspinatus  and  the  teres  minor. 

The  elbow-joint  is  a  ginglyruus  or  hinge-joint. 
The  larger  sigmoid  cavity  of  the  ulna  is  adapted 
to  the  trochlea  upon  the  lower  end  of  the  humerus,  admitting  only 
of  flexion  and  extension ;  while  the  shallow  excavation  upon  the 

FIG.  94. 


ELBOW-JOINT. 


«.  External  lateral  liga-     CL 
ment. 

6.  Orbicular  or  annular 
ligament. 


c.  Part  of  internal  la- 

teral ligament. 

d.  Radius,        removed 

from   the   annular 
ligament. 


LIGAMENTS    OF    THE    ELBOW-JOINT. 


head  of  the  radius  admits  not  only  of  flexion  and  extension,  but  of 
central  rotation,  upon  the  rounded  articular  eminence  (capitellum) 
of  the  humerus,  and  of  peripheral  rotation  at  the  superior  radio- 
ulnar  articulation. 

The  joint  is  secured  in  front  and  behind  by  anterior  and 
posterior  ligaments,  and  laterally  by  two  strong  lateral  ligaments. 
No  ligament  is  attached  to  the  head  of  the  radius,  otherwise  its" 
rotatory  movement  would  be  impeded.  The  head  is  simply  sur- 
rounded by  a  ligamentous  collar,  called  the  annular  ligament, 
within  which  it  freely  rolls  in  pronation  and  supination  of  the  hand. 


SUPERIOR   RADIO-ULNAR  ARTICULATION.  409 

The  anterior  ligament  consists  of  broad  thin  ligamentous  fibres, 
attached  above  to  the  front  of  the  humerus,  above  the  coro- 
noid  fossa,  below  to  the  coronoid  process  of  the  ulna  and  to  the 
orbicular  ligament,  and  continuous  on  each  side  with  the  lateral 
ligaments.  Some  of  the  fibres  cross  each  other  at  right  angles. 

The  posterior  ligament  is  composed  of  thin  loose  fibres  attached 
above  to  the  margin  of  the  olecranon  fossa,  below  to  the  border  of 
the  olecranon,  and  spread  over  the  posterior  aspect  of  the  joint. 

The  internal  lateral  ligament  is  triangular,  and  is  divided  into 
two  portions,  an  anterior  and  a  posterior.  Its  anterior  part  is 
attached  to  the  front  of  the  internal  condyle  of  the  humerus  :  from 
this  point  the  fibres  radiate,  and  are  inserted  along  the  inner  mar- 
gin of  the  coronoid  process  of  the  ulna.  The  posterior  part  is  also 
triangular,  and  passes  from  the  back  part  of  the  internal  condyle 
to  the  inner  border  of  the  olecranon. 

A  band  of  fibres  extends  transversely  from  the  olecranon  to  the 
coronoid  process,  across  a  notch  observable  on  the  inner  side  of  the 
sigmoid  cavity :  through  this  notch  small  vessels  pass  into  the  joint. 

The  external  lateral  ligament  is  attached  to  the  external  condyle 
of  the  humerus,  and  is  in  intimate  connection  with  the  common 
tendon  of  the  extensors.  The  fibres  spread  out  as  they  descend, 
and  are  interwoven  with  the  annular  ligament  surrounding  the 
head  of  the  radius. 

The  preceding  ligaments,  collectively,  form  a  continuous  cap- 
sule for  the  joint. 

SUPEEIOE  The  orbicular  or  annular  ligament  of  the  radius 

BADIO-ULNAB  forms  about  three-fourths  of  a  ring.     Its  ends  are 

AKTICULATION.  attached  to  the  anterior  and  posterior  borders  of 
the  lesser  sigmoid  cavity  of  the  ulna,  and  is  broader  in  the  middle 
than  at  either  end.  Its  lower  border  is  straight ;  its  upper  border  is 
convex,  and  connected  with  the  anterior  and  external  lateral  liga- 
ments. With  this  sigmoid  cavity  it  forms  a  complete  collar,  which 
encircles  the  head,  and  part  of  the  neck,  of  the  radius.  The  lower 
part  of  the  ring  is  narrower  than  the  upper,  the  better  to  clasp  the 
neck  of  the  radius,  and  maintain  it  more  accurately  in  position. 

Synovial  membrane  of  the  elboiv-joint. — Open  the  joint  by  a 
transverse  incision  in  front,  and  observe  the  relative  adaptation  of 


410  INTEROSSEOUS   MEMBRANE. 

the  cartilaginous  surfaces  of  the  bones.  The  synovial  membrane 
lines  the  interior  of  the  capsule,  and  forms  a  cul-de-sac  between 
the  head  of  the  radius  and  its  annular  ligament.  It  is  widest  and 
loosest  under  the  tendon  of  the  triceps.  Where  the  membrane  is 
reflected  from  the  bones  upon  the  ligaments,  there  is  more  or  less 
adipose  tissue,  particularly  in  the  fossas  on  the  front  and  back  part 
of  the  lower  end  of  the  humerus. 

The  only  movements  permitted  between  the  humerus  and  the 
ulna  are  those  of  flexion  and  extension,  both  of  which  are  limited 
by  the  ligaments  and  tendons  in  front  of  and  behind  the  joint,  and 
probably  not  by  the  coronoid  and  olecranon  processes.  The  head 
of  the  radius  is  most  in  contact  with  the  capitellum  of  the  humerus 
during  semiflexion  and  semipronation ;  and  it  is  kept,  by  the  strong 
orbicular  ligament  which  surrounds  the  neck  of  the  radius,  from 
being  dislocated  forwards  by  the  biceps.  The  movement  at  the 
superior  radio-ulnar  articulation  is  that  of  rotation  in  the  lesser 
sigmoid  cavity  of  the  ulna,  forming  an  example  of  a  lateral  gin- 
glymus  or  diarthrosis  rotatoria.  It  is  by  this  rotation  of  the  head 
of  the  radius,  that  the  hand  is  carried  through  an  extensive  range 
of  pronation  and  supination ;  for  it  is  articulated  only  to  the  lower 
end  of  the  radius,  the  ulna  being  excluded  by  the  interarticular 
fibre-cartilage  from  taking  any  share  in  the  movement  at  the  wrist- 
joint. 

INTEBOSSEOUS  This  is  an   aponeurotic   septum,  stretched  be- 

MEMBRANE.  tween  the  interosseous  ridges  of  the  radius  and 

ulna,  of  which  the  chief  purpose  is  to  afford  an  increase  of  surface 
for  the  attachment  of  muscles.  The  septum  is  deficient  above, 
beginning  about  an  inch  below  the  tubercle  of  the  radius,  and  thus 
permits  free  rotation  of  that  bone.  Its  fibres  extend  obliquely 
downwards  from  the  radius  to  the  ulna.  It  is  perforated  in  its 
lower  third  by  the  anterior  interosseous  vessels. 

The  name  of  round  or  oblique  ligament  is  given  to  a  thin  band 
of  fibres,  which  extends  obliquely  between  the  bones  of  the  fore- 
arm in  a  direction  contrary  to  those  of  the  interosseous  membrane. 
It  is  attached,  superiorly,  to  the  front  surface  of  the  ulna,  near  the 
outer  side  of  the  coronoid  process ;  inferiorly,  to  the  radius  imme- 
diately below  the  tubercle.  Between  this  ligament  and  the  upper 


INFERIOR   RADIO-ULNAR  ARTICULATION.  411 

border  of  the  interosseous  membrane  is  a  triangular  interval  through 
which  the  posterior  interosseous  artery  passes  to  the  back  of  the 
forearm.  A  bursa  intervenes  between  the  oblique  ligament  and 
the  insertion  of  the  tendon  of  the  biceps.  The  use  of  this  ligament 
is  to  limit  supination  of  the  radius. 

INFERIOR  This  joint  is  a  lateral  ginglynius,  and  is  formed 

RADIO-ULNAR  by  the  inner  concave  surface  of  the  lower  end  of 

ARTICULATION.  fae  ra<Jius  rotating  upon  the  convex  head  of  the 
ulna ;  which  mechanism  is  essential  to  the  pronation  and  supina- 
tion of  the  hand.  These  corresponding  surfaces  are  encrusted  with 
a  thin  layer  of  cartilage,  and  are  provided  with  a  very  loose  syn- 
ovial  membrane.  The  surfaces  are  maintained  in  position  by  an 
anterior  and  a  posterior  radio-ulnar  ligament,  and  a  triangular 
fibro-cartilage. 

The  anterior  radio-ulnar  ligament  is  a  thin  fasciculus  extending 
obliquely  inwards  from  the  anterior  border  of  the  sigmoid  cavity  of 
the  radius  to  the  head  of  the  ulna. 

The  posterior  radio-idnar  ligament  passes  from  the  posterior 
border  of  the  sigmoid  cavity  to  the  posterior  surface  of  the  styloid 
process  of  the  ulna. 

The  triangular  fibro-cartilage  between  the  radius  and  ulna  is 
the  principal  uniting  medium  between  the  bones.  To  see  it,  saw 
through  the  bones  of  the  forearm,  and  separate  them  by  cutting 
through  the  interosseous  membrane,  and  opening  the  synovial 
membrane  of  the  joint  between  the  lower  ends.  Thus  a  good  view 
is  obtained  of  the  fibro-cartilage  which  connects  them  (fig.  95). 
It  is  triangular,  and  placed  transversely  at  the  lower  end  of  the 
ulna,  filling  up  the  interval  caused  by  the  greater  length  of  the 
radius.  Its  base  is  attached  to  the  lower  end  of  the  radius ;  its 
apex  to  a  depression  at  the  root  of  the  styloid  process  of  the  ulna. 
It  is  thin  at  the  base  and  centre,  thicker  at  the  apex  and  sides. 
Its  upper  surface  is  in  contact  with  the  ulna,  and  covered  by  the 
synovial  membrane  of  the  inferior  radio-ulnar  joint ;  its  lower 
surface,  forming  a  part  of  the  wrist-joint,  is  contiguous  with  the 
cuneiform  bone.  Its  borders  are  connected  with  the  anterior  and 
posterior  ligaments  of  the  wrist.  In  some  instances  there  is  an 
aperture  in  the  centre. 


412 


THE   WRIST-JOINT. 


When,  from  accident  or  disease,  this  fibro-cartilage  gets  de- 
tached from  the  radius,  the  consequence  is  an  abnormal  projection 
of  the  lower  end  of  the  ulna. 

The  synovial  membrane  of  this  joint  is  distinct  from  that  of 
the  wrist,  except  in  the  case  of  a  perforation  through  the  nbro- 
cartilage.  On  account  of  its  great  looseness,  necessary  for  the  free 
rotation  of  the  radius,  it  is  called  membrana  sacciformis. 

The  movement  between  the  lower  ends  of  the  radius  and  ulna 
is  due  to  the  rotation  of  the  radius  round  the  articular  head  of  the 

FIG.  95. 


1.  External  lateral  liga- 

ment. 

2.  Internal  lateral  liga- 

ment. 

3.  Interarticular  flbro- 

cartilage    between 
radius  and  ulna. 


4.  Interosseous  liga- 

ments. 

5.  Lateral   ligaments 

of    the   intercar- 
pal  joint. 


DIAGBAM   OF   THE   LIGAMENTS   AND    SYNOVIAL   MEMBBANE8   OF   THE    WKIST-JOINT. 

ulna,  and  is  confined  to  rotation  forwards  or  pronation,  and  to  rota- 
tion backwards  or  supination  :  the  extent  of  movement  being  limited 
by  the  anterior  and  posterior  ligaments. 

EADIO-CAEPAL  This  is  an  arthrodial  joint,  and  is  formed :  above, 

OB  WBIST-JOINT.  by  the  lower  end  of  the  radius  and  the  distal  sur- 
face of  the  triangular  fibre-cartilage  ;  below,  by  the  scaphoid,  semi- 
lunar  and  cuneiform  bones  ;  the  two  former  articulate  with  the  two 
facets  on  the  radius,  the  latter  with  the  fibro-cartilage.  The  three 


CARPAL   ARTICULATIONS.  413 

carpal  bones  form  a  convex  surface  which  is  received  into  the  con- 
cavity formed  by  the  radius  and  the  cartilage.  The  joint  is  secured 
by  an  anterior,  a  posterior  and  two  lateral  ligaments. 

The  external  lateral  ligament  extends  from  the  tip  of  the  styloid 
process  of  the  radius  to  the  outer  side  of  the  scaphoid  bone,  to  the 
anterior  annular  ligament,  and  to  the  trapezium. 

The  internal  lateral  ligament  is  round,  and  proceeds  from  the 
extremity  of  the  styloid  process  of  the  ulna  to  the  cuneiform  bone. 
Another  fasciculus  is  attached  to  the  pisiform  bone  and  the  anterior 
annular  ligament. 

The  anterior  ligament  consists  of  two  or  more  broad  bands  of 
ligamentous  fibres,  which  extend  from  the  lower  end  of  the  radius 
to  the  first  row  of  carpal  bones,  except  the  pisiform. 

The  posterior  ligament,  weaker  than  the  preceding,  proceeds 
from  the  posterior  surface  of  the  lower  end  of  the  radius,  and  is 
attached  to  the  posterior  surfaces  of  the  first  row  of  carpal  bones. 

The  synovial  membrane  lines  the  under  surface  of  the  triangular 
fibro-cartilage  at  the  end  of  the  ulna,  is  reflected  over  the  several 
ligaments  of  the  joint,  and  thence  upon  the  first  row  of  the  carpal 
bones  (fig.  95). 

This  articulation  allows  of  all  the  movements  of  enarthrodial 
joints,  except  that  of  rotation  :  thus,  it  allows  of  flexion,  extension, 
abduction,  adduction,  and  circumduction,  so  that  it  is,  strictly 
speaking,  only  an  arthrodial  joint. 

The  bones  of  the  carpus  are  arranged  in  two 
CARPAL  JOINTS. 

rows,  an  upper  and  a  lower,  adapted  to  each  other 

so  as  to  form  between  them  a  joint.  The  articulations  may  be  best 
arranged  in  three  sets :  those  between  the  carpal  bones  of  the  first 
row ;  between  those  of  the  second  row ;  and  the  articulation  of  the 
two  rows  with  each  other  :  they  are  all  examples  of  arthrodial  joints. 

a.  The  first  row  of  carpal  bones  are  connected  together  by  two 
palmar,  two  dorsal,  and  two  interosseous  ligaments. 

The  dorsal  and  palmar  transverse  ligaments  proceed,  on  the 
dorsal  and  palmar  aspects,  from  the  scaphoid  to  the  semilunar  bone, 
and  from  the  semilunar  to  the  cuneiform  bone  :  the  dorsal  being  the 
stronger ;  the  interosseous  ligaments  connect  the  semilunar  with 
the  bones  on  each  side  of  it  (fig.  95). 


414  CARPAL   ARTICULATIONS. 

The  pisiform  bone  is  articulated  to  the  palmar  surface  of  the 
cuneiform  bone,  to  which  it  is  united  by  a  fibrous  capsule.  In- 
feriorly,  it  is  attached  by  two  strong  ligaments,  the  one  to  the 
unciform  bone,  the  other  to  the  carpal  end  of  the  fifth  metacarpal 
bone.  This  articulation  has  a  distinct  synovial  membrane. 

5.  The  second  row  of  carpal  bones  is  connected  by  three  dorsal, 
three  palmar,  and  two  interosseous  ligaments. 

The  dorsal  and  palmar  ligaments  pass  transversely  from  one  to 
the  other.  There  are  usually  two  interosseous  ligaments,  one  on 
either  side  of  the  os  magnum  ;  sometimes  there  is  a  third,  between 
the  trapezium  and  trapezoid  bones  ;  they  are  thicker  and  stronger 
than  those  of  the  upper  row,  and  unite  the  bones  more  firmly 
together. 

c.  The  first  row  of  carpal  bones  is  arranged  in  the  form  of  an 
arch,  so  as  to  receive  the  corresponding  surfaces  of  the  os  magnum 
and  unciforme.  External  to  the  os  magnum,  the  trapezium  and 
trapezoid  bones  present  a  slightly  concave  surface,  which  articulates 
with  the  scaphoid.  In  this  way  a  joint,  admitting  of  flexion  and 
extension  only,  is  formed  between  the  upper  and  lower  row. 

The  two  rows  of  carpal  bones  are  connected  together  by  palmar 
and  dorsal  ligaments,  and  by  an  external  and  an  internal  lateral 
ligament. 

The  palmar  ligaments  consist  of  strong  ligamentous  fibres, 
which  pass  obliquely  from  the  bones  of  the  first  to  those  of  the 
second  row. 

The  dorsal  ligaments  consist  of  oblique  and  transverse  fibres 
which  connect  the  dorsal  surfaces  of  the  bones  of  the  upper  with 
the  lower  row. 

The  external  lateral  ligament,  very  distinct,  passes  from  the 
scaphoid  to  the  trapezium ;  the  internal  lateral  ligament  from  the 
cuneiform  to  the  unciform. 

Divide  the  ligaments  to  see  the  manner  in  which  the  carpal 
bones  articulate  with  one  another.  Their  surfaces  are  crusted  with 
cartilage,  and  have  a  common  synovial  membrane  which  is  very  ex- 
tensive and  lines  the  distal  surfaces  of  the  scaphoid,  seniilunar,  and 
cuneiform  bones  ;  it  then  passes  forwards  between  the  trapezium 
and  trapezoid,  the  trapezoid  and  os  magnum,  the  os  magnum  and 


CARPO-METACARPAL   ARTICULATIONS.  415 

the  cuneiform  to  the  articulations  between  the  second  row  of  carpal 
bones  and  the  metacarpal  bones  of  the  four  fingers  (fig.  95). 

JOINT  BETWEEN  TJie  trapezium  presents  a  cartilaginous  surface, 
TRAPEZIUM  AND  convex  in  the  transverse,  and  concave  in  the 
THE  FIRST  META-  antero- posterior  direction  (i.e.  saddle-shaped), 
CAEPAL  BONE.  which  articulates  with  the  cartilaginous  surface  on 

the  metacarpal  bone  of  the  thumb,  concave  and  convex  in  the 
opposite  directions.  This  peculiar  adaptation  of  the  two  surfaces 
permits  the  several  movements  of  the  thumb — viz.,  flexion,  exten- 
sion, abduction  and  adduction ;  consequently  circumduction.  It 
is  an  arthrodial  joint,  but  permits  of  such  extensive  movement, 
that  it  is  described  by  some  anatomists  as  one  by  '  reciprocal  re- 
ception.' Thus  we  are  enabled  to  oppose  the  thumb  to  all  the 
fingers,  which  is  one  of  the  great  characteristics  of  the  human 
hand.  The  joint  is  surrounded  by  a  capsular  ligament  suffici- 
ently loose  to  admit  free  motion,  and  stronger  on  the  dorsal  than 
on  the  palmar  aspect.  The  security  of  the  joint  is  increased 
by  the  muscles  which  surround  it.  It  has  a  separate  synovial 
'membrane. 

CARPO-META-  The  metacarpal  bones  of  the  fingers  are  con- 

CAHPAL  JOINTS.  nected  to  the  second  row  of  the  carpal  bones  by 
ligaments  upon  their  palmar  and  dorsal  surfaces,  and  by  interosseous 
ligaments. 

The  dorsal  ligaments  are  the  stronger.  The  metacarpal  bone 
of  the  forefinger  has  two  :  one  from  the  trapezium,  the  other  from 
the  trapezoid  bone.  That  of  the  middle  finger  has  also  two,  proceed- 
ing from  the  os  magnum  and  the  os  trapezoides.  That  of  the 
ring  finger  has  also  two,  proceeding  from  the  os  magnum  and  the 
unciform  bone.  That  of  the  little  finger  has  one  only,  from  the 
unciform  bone. 

The  palmar  ligaments  are  arranged  nearly  upon  a  similar  plan. 
The  metacarpal  bone  of  the  forefinger  has  one  from  the  trapezoid 
bone.  That  of  the  middle  finger  has  three,  proceeding  from  the 
trapezium,  the  os  magnum,  and  the  unciform  bone.  Those  of  the 
ring  and  little  fingers  have  each  one,  from  the  unciform  bone. 

Besides  the  preceding  ligaments,  there  are  some  of  considerable 
strength,  called  the  interosseous.  They  proceed  from  the  adjacent 


416  SYNOVIAL   MEMBRANES   OF   THE   WRIST. 

sides  of  the  os  magnum  and  the  os  unciforme,  descend  vertically, 
and  are  fixed  into  the  radial  side  of  the  metacarpal  bone  of  the 
middle  and  ring  fingers  (fig.  95).  This  ligament  occasionally 
isolates  the  synovia!  membrane  of  the  two  inner  metacarpal  bones 
from  the  common  synovial  membrane  of  the  carpus. 

Separate  the  metacarpal  bones  from  the  carpus,  and  observe 
the  relative  form  of  their  contiguous  surfaces.  The  metacarpal 
bones  of  the  fore  and  middle  fingers  are  adapted  to  the  carpus  in 
such  an  angular  manner  as  to  be  almost  immoveable.  The  meta- 
carpal bone  of  the  ring  finger,  having  a  plane  articular  surface 
with  the  unciform  bone,  admits  of  more  motion.  Still  greater 
motion  is  permitted  between  the  unciform  and  the  metacarpal  bone 
of  the  little  finger,  the  articular  surfaces  of  each  being  slightly 
concave  and  convex  in  opposite  directions.  The  greater  freedom 
of  motion  of  the  metacarpal  bone  of  the  little  finger  is  essential  to 
the  expansion  and  contraction  of  the  palm. 

The  carpal  extremities  of  the  metacarpal  bones  of  the  fingers  are 
connected  with  each  other  by  palmar  and  dorsal  transverse  liga- 
ments. They  are  also  connected  by  interosseous  ligaments,  which 
extend  between  the  bones,  immediately  below  their  contiguous 
cartilaginous  surfaces. 

The  distal  extremities  of  these  bones  are  loosely  connected  on 
their  palmar  aspect  by  the  transverse  metacarpal  ligament. 

SYNOVIAL  MEM-  There  are  five,  sometimes  six,  distinct  synovial 
BRAKES  OF  THE  membranes,  proper  to  the  lower  end  of  the  radius, 
WRIST,  and  the  several  bones  of  the  carpus  (see  the 

diagram,  p.  412)  as  follows  :— 

a.  One  between  the  lower  end  of  the  radius  and  the  ulna. 

b.  One  between  the  radius  and  the  first  row  of  carpal  bones. 

c.  One  between  the  trapezium  and  the  metacarpal  bone  of  the 

thumb. 

d.  One  between  the  cuneiform  and  pisiform  bones. 

e.  One  between  the  first  and  second  rows  of  carpal  bones  (the 

intercarpal  joint).     This  extends  to  the  metacarpal  bones 
of  the  four  inner  fingers. 

The  interosseous  ligament  between  the  os  magnum  and  ring 
finger  occasionally  shuts  off  the  synovial  membrane  between  the 


METACARPO-PHALAXGEAL   ARTICULATION-.  417 

unciform  and  two  inner  metacarpal  bones  from  the  large  intercarpal 
sac  :  thus  making  the  sixth  distinct  synovial  membrane. 

FIRST  Jonrr  OP          The  first  phalanx  of  the  finger  presents  a  shallow 
THE  FIXGERS.  oval  cavity,  crusted  with  cartilage,  with  the  broad 

diameter  in  the  transverse  direction,  to  articulate  with  the  round 
cartilaginous  head  of  the  metacarpal  bone,  of  which  the  articular 
surface  is  elongated  in  the  antero-posterior  direction,  and  of  greater 
extent  on  its  palmar  than  its  dorsal  aspect.  This  formation  of 
parts  permits  flexion  of  the  finger  to  a  greater  degree  than  exten- 
sion ;  and  also  a  slight  lateral  movement. 

Each  joint  is  provided  with  two  strong  lateral  ligaments,  and 
an  anterior  or  palmar  ligament. 

The  lateral  ligaments  arise  from  the  tubercles  on  either  side  of 
each  metacarpal  bone,  and,  inclining  slightly  forward,  are  inserted 
into  the  sides  of  the  base  of  the  first  phalanx  of  the  finger. 

The  anterior  (glenoid)  ligament  is  a  thick,  compact,  fibrous 
structure,  which  extends  over  the  palmar  surface  of  the  joint  be- 
tween the  lateral  ligaments.  Its  distal  end  is  firmly  attached  to  the 
base  of  the  first  phalanx  of  the  finger ;  its  proximal  end  is  loosely 
adherent  to  the  rough  surface  above  the  head  of  the  metacarpal 
bone.  On  either  side  it  is  inseparably  connected  with  the  lateral 
ligaments,  so  that  with  them  it  forms  a  strong  capsule  over  the 
front  and  sides  of  the  joint.  Its  superficial  surface,  firmly  con- 
nected with  the  transverse  ligament,  is  slightly  grooved  for  the 
play  of  the  flexor  tendons ;  its  deep  surface  is  adapted  to  cover  the 
head  of  the  metacarpal  bone.  Two  sesamoid  bones  are  found  in 
the  palmar  ligament  belonging  to  the  joint  between  the  metacarpal 
bone  and  the  first  phalanx  of  the  thumb. 

The  palmar  ligaments  have  a  surgical  importance  for  the  follow- 
ing reason : — In  dislocation  of  the  fingers,  the  facility  of  reduction 
mainly  depends  upon  the  extent  to  which  the  glenoid  ligament  is 
injured.  If  it  be  much  torn,  there  is  but  little  difficulty  :  if  entire, 
the  reduction  may  require  much  manipulation. 

These  joints  are  secured  on  their  dorsal  aspect  by  the  extensor 
tendon,  and  the  expansion  proceeding  from  it  on  either  side. 
Their  synovial  membranes  are  loose,  especially  beneath  the  extensor 
tendons. 

£  E 


418  PHALANGEAL   ARTICULATIONS. 

SECOND  AND  The  corresponding  articular  surfaces  of  the  pha- 

LAST  JOINT  OF  langes  of  the  fingers  and  thumb  are  so  shaped  as 

THE  FINGERS.  ^o  form  a  hinge-joint,  and,  therefore,  incapable  of 

lateral  movement.  The  ligaments  connecting  them  are  similar  in 
every  respect  to  those  between  the  metacarpal  bones  and  the  first 
phalanges.  The  palmar  ligament  of  the  last  joint  of  the  thumb 
generally  contains  a  sesamoid  bone. 

The  wrist-joint  is  a  complex  articulation,  in  which  the  seat  of 
movement  is  partly  in  the  radio-carpal,  and  partly  in  the  inter- 
carpal  articulation.  Thus  the  hand  at  the  radio-carpal  joint  is 
capable  of  extension  (dorsi-flexion)  and  flexion,  the  latter  being  the 
most  free ;  it  is  also  capable  of  adduction  (ulnar  flexion)  and  of 
abduction  (radial  flexion)  to  a  lesser  extent.  Between  the  carpal 
bones  and  carpo-rnetacarpal  bones,  the  movement  which  takes  place 
when  the  hand  is  pressed  down  so  as  to  support  the  weight  of  the 
body,  is  that  of  separation  of  the  anterior  part  of  their  apposed 
surfaces  ;  undue  separation  being  prevented  by  the  interosseous 
and  palmar  ligaments.  The  articulation  between  the  unciform  and 
fourth  and  fifth  metacarpals  is  not  so  firm  as  that  between  the  other 
carpo-metacarpal  bones,  consequently  there  is  greater  freedom  of 
motion  forwards,  seen  in  deepening  the  palm  and  in  shutting  the 
hand.  The  movements  at  the  metacarpo-phalangeal  articulation 
are  those  of  extension  and  flexion,  of  adduction  and  abduction,  the 
two  latter  being  most  marked  in  extension  of  the  finger.  Between 
the  thumb  and  trapezium  all  the  movements  of  an  enarthrodial 
joint  exist,  except  that  of  rotation ;  a  little  rotation  probably  takes 
place  when  the  metacarpal  bone  is  flexed.  In  the  interphalangeal 
and  phalangeal  joints,  the  only  movements  permitted  are  those 
of  extension  and  flexion. 


419 


DISSECTION  OF  THE  ABDOMEN. 

SURFACE  THE  body  should  be  sufficiently  raised  by  placing 

MASKING.  blocks  beneath  the  buttocks  and  the  shoulders, 

care  being  taken  to  have  the  chest  higher  than  the  pelvis. 

In  the  middle  line,  extending  from  the  ensiform  cartilage  to  the 
symphysis  pubis,  is  a  groove  caused  by  the  linea  alba,  the  line  of 
union  of  the  aponeuroses  of  the  abdominal  muscles.  In  this  middle 
line,  nearer  the  os  pubis  than  the  ensiform  cartilage,  is  the  umbilicus, 
which  corresponds  as  a  rule  with  the  body  of  the  third  lumbar  ver- 
tebra. The  recti  muscles  can  be  distinguished  on  each  side  of  the 
middle  line,  and  in  well-developed  subjects  with  little  fat,  the  lineee 
transversse  may  be  recognised,  the  lowest  one  being  at  the  umbilicus, 
the  highest  on  a  level  with  the  ensiform  cartilage,  and  the  third  one 
midway  between  the  two.  On  the  outer  border  of  the  rectus,  about 
three  inches  from  the  middle  line,  is  a  concave  line,  the  linea  semi- 
lunaris,  corresponding  to  the  separation  of  the  aponeurosis  of  the 
abdominal  muscles  to  form  the  sheath  of  the  rectus.  Above,  and 
external  to  the  spine  of  the  os  pubis,  the  external  abdominal  ring 
can  be  easily  felt,  the  outer  pillar  being  the  stronger ;  on  it  rests 
the  spermatic  cord  passing  to  the  testis.  Passing  from  the  spine 
of  the  os  pubis  to  the  anterior  superior  spine  of  the  ilium,  is  a 
crescentic  groove  which  indicates  the  line  of  Poupart's  ligament, 
and  which  can  be  felt  as  a  firm  and  slightly  curved  cord  ;  at  about 
half  an  inch  above  the  middle  of  the  ligament  is  situated  the 
internal  abdominal  ring,  which  cannot,  however,  be  felt. 
ARBITRARY  The  abdomen  is  divided  into  arbitrary  regions, 

DIVISION  INTO           that  the  situation  of  the  viscera  contained  in  it 
REGIONS.  mav  be  m0re  easily  described.     For  this  purpose 

we  draw  the  following  lines  : — one  horizontally  across  the  abdomen 
on  a  level  with  the  cartilages  of  the  ninth  ribs ;  another  on  a  level 

E   E   2 


420 


ABDOMINAL   REGIONS. 


FIG.  96. 


with  the  anterior  superior  spines  of  the  ilia.  These  lines  form 
the  boundaries  of  three  spaces,  each  of  which  is  subdivided  into 
three  regions  by  a  vertical  line  drawn  on  each  side  from  the  carti- 
lage of  the  eighth  rib  to  the  middle 
of  Poupart's  ligament.  Thus,  there 
are  a  central  and  two  lateral  regions 
in  each  space.  The  central  region 
of  the  upper  space  is  termed  the 
epigastric ;  the  central  one  of  the 
middle  space  is  called  the  umbilical 
region ;  and  the  central  of  the  in- 
ferior space,  the  hypogastric  region. 
The  lateral  regions  of  the  spaces  from 
above  downwards  are  termed  the 
right  and  left  hypochondriac,  the 
right  and  left  lumbar,  and  the  right 
and  left  inguinal  or  iliac  regions, 
respectively. 

The  viscera  contained   in  these 
respective  regions  are  as  follows : — 

In  the  epigastric  region  are,  the  left  lobe  of  the  liver,  the  round 
ligament  of  the  liver,  a  small  part  of  the  right  lobe,  the  middle  and 
pyloric  end  of  the  stomach,  the  lobulus  Spigelii,  the  pancreas,  and 
the  upper  border  of  the  transverse  colon. 

In  the  umbilical  region  are,  the  transverse  colon,  the  great 
omentum  and  mesentery,  the  round  ligament  of  the  liver,  the 
transverse  portion  of  the  duodenum,  and  part  of  the  jejunum  and 
ileum. 

In  the  hypogastric  region  are,  the  small  intestines,  the  urachus, 
the  two  obliterated  hypogastric  arteries,  the  bladder  naturally  in 
early  life,  and  in  the  adult  if  distended  ;  and,  lastly,  the  uterus  in 
pregnancy. 

In  the  right  hypochondriiim  are,  the  right  lobe  of  the  liver,  the 
base  of  the  gall-bladder,  the  descending  duodenum,  the  hepatic 
flexure  of  the  colon,  pancreas,  supra-renal  capsule,  and  the  upper 
part  of  the  right  kidney. 

In  the  left  hypochondrium  are,  the  cardiac  end  of  the  stomach, 


SUPERFICIAL   FASCIA   OF   THE   ABDOMEN.  421 

the  greater  part  of  the  spleen,  the  tail  of  the  pancreas,  the  splenic 
flexure  of- the  colon,  the  supra-renal  capsule,  and  the  upper  part  of 
the  left  kidney. 

In  the  right  lumbar  region  are,  the  ascending  colon,  the  lower 
part  of  the  right  kidney,  and  small  intestines. 

In  the  left  lumbar  region  are,  the  descending  colon,  the  lower 
part  of  the  left  kidney,  omentum,  and  small  intestines. 

In  the  right  inguinal  region  are,  the  cascum  and  appendix  vermi- 
formis. 

In  the  left  inguinal  region  is  the  sigmoid  flexure  of  the  colon. 

The  abdomen  should  at  this  stage  be  distended  with  air  by 
means  of  a  blow-pipe  inserted  into  the  abdominal  cavity  through  the 
umbilicus,  which,  on  the  removal  of  the  blow-pipe,  should  be  tied 
with  string  to  prevent  escape  of  the  air. 

An  incision  is  to  be  made  from  the  ensiform 
cartilage  to  the  os  pubis,  another  from  the  anterior 
superior  spine  of  the  ilium  to  a  point  midway  between  the  umbilicus 
and  os  pubis,  and  a  third  from  the  ensiform  cartilage,  transversely 
outwards  towards  the  axilla  as  far  as  the  angles  of  the  ribs.  The 
skin  should  then  be  dissected  from  the  subjacent  adipose  and  con- 
nective tissue,  called  the  superficial  fascia. 

SUPERFICIAL  The  subcutaneous  tissue  of  the  abdomen  has 

FASCIA.  the  same  general  characters  as  that  of  other  parts, 

and  varies  in  thickness  in  different  persons,  according  to  the 
amount  of  fat.  At  the  lower  part  of  the  abdomen,  it  admits  of 
separation  into  two  layers,  between  which  are  found  the  subcuta- 
neous blood-vessels,  the  lymphatic  glands,  the  ilio-inguinal  nerve, 
and  the  hypogastric  branch  of  the  ilio-hypogastric  nerve. 

Respecting  the  superficial  layer,  observe  that  it  contains  the 
fat,  and  is  continuous  with  the  superficial  fascia  of  the  thigh,  the 
scrotum,  and  the  perineum.  The  deeper  layer  is  intimately  con- 
nected with  Poupart's  ligament  and  the  linea  alba ;  but  it  is  very 
loosely  continued  over  the  spermatic  cord  and  the  scrotum,  and 
becomes  identified  with  the  deep  layer  of  the  superficial  fascia  of 
the  perineum.  These  points  deserve  attention,  since  they  explain 
how  urine,  extravasated  into  the  perineum  and  scrotum,  readily 
makes  its  way  over  the  spermatic  cord  on  to  the  surface  of  the 


422 


SUPERFICIAL   VESSELS   OF   THE   GROIN. 


abdomen ;  but  from  this  it  cannot  travel  down  the  thigh  on  account 
of  the  connection  of  the  fascia  with  Poupart's  ligament. 

Between  the  layers  of  the  superficial  fascia  in 
the  groin  and  upper  part  of  the  thigh,  are  several 
lymphatic  glands  and  small  blood-vessels  (fig.  97). 
The  glands  are  named,  according  to  their  situa- 

FIG.  97. 


SUPERFICIAL 
BLOOD-VESSELS 
AND  LYMPHATIC 
GLANDS. 


SUPERFICIAL   VESSELS   AND   GLANDS   OK   THE    GROIN. 


1.  Saphenous  opening  of  the  fascia  lata. 

2.  Saphena  vein. 

3.  Superficial  epigastric  a. 

4.  Superficial  circumflexa  ilii  a. 


5.  Superficial  external  pudic  a. 

6.  External  abdominal  ring. 

7.  Fascia  lata  of  the  thigh. 


tion,  inguinal  or  femoral.  The  inguinal,  from  three  to  four  in 
number,  are  often  small,  and  escape  observation.  They  are  of  an 
oval  form,  with  their  long  axis  corresponding  to  the  line  of  the 
crural  arch  (represented  by  the  dark  line  in  fig.  97).  They  re- 
ceive the  superficial  lymphatics  from  the  lower  part  of  the  wall  of 
the  abdomen,  from  the  integument  of  the  scrotum,  penis,  perineum, 


CUTANEOUS  NERVES  OF  THE  GROIN.  423 

anus,  and  gluteal  region,  and  are  therefore  generally  affected  in 
venereal  disease.  The  lymphatics  from  the  upper  part  of  the 
abdominal  parietes  terminate  in  the  lumbar  glands. 

The  superficial  arteries  in  the  neighbourhood  arise  from  the 
femoral.  One,  the  superficial  epigastric,  ascends  over  Poupart's 
ligament  and  ramifies  over  the  lower  part  of  the  abdomen,  as  high 
as  the  umbilicus,  inosculating  with  the  deep  epigastric  and  in- 
ternal mammary  arteries  ;  another,  the  superficial  external  pudic, 
crosses  the  spermatic  cord,  and  is  distributed  to  the  skin  of  the 
penis  and  scrotum,  anastomosing  with  branches  of  the  internal 
pudic ;  a  third,  the  superficial  circumflexa  ilii,  ramifies  towards  the 
spine  of  the  ilium,  and  communicates  with  the  deep  circumflex 
iliac,  the  gluteal  and  external  circumflex  arteries.  These  subcuta- 
neous arteries,  the  pudic  especially,  often  occasion  a  free  haemor- 
rhage in  the  operation  for  strangulated  inguinal  and  femoral 
hernia. 

The  corresponding  veins  join  the  internal  saphena  vein  of  the 
thigh.  Under  ordinary  circumstances  they  do  not  appear  in  the 
living  subject;  but  when  any  obstruction  occurs  in  the  inferior 
vena  cava,  they  become  enlarged  and  tortuous,  and  constitute  the 
chief  channels  through  which  the  blood  would  be  returned  from 
the  lower  limbs.1 

CUTANEOUS  The  skin  of  the  abdomen  is  supplied  with  nerves 

NEBVES.  after  the   same  plan   as   the   chest — namely,  by 

lateral  and  anterior  branches  derived  from  the  five  or  six  lower 
intercostal  nerves,  as  follows  : — 

a.  The  lateral  cutaneous  nerves  come  out  between  the  digita- 
tions  of  the  external  oblique  muscle,  in  company  with  small 
arteries,  and  divide,  except  the  last,  into  anterior  and  posterior 
branches ;  the  anterior  pass  forwards  as  far  as  the  rectus,  and  are 
distributed  to  the  skin  as  far  as  its  outer  border,  and  to  the  digita- 
tions  of  the  obliquus  externus  muscle  ;  the  posterior,  small  in  size, 
run  backwards  and  supply  the  skin  over  the  latissimus  dorsi.  The 
lateral  branch  of  the  tivelfth  dorsal  nerve  is  larger  than  the  others, 
and,  piercing  both  the  oblique  muscles,  passes  over  the  crest  of  the 

1  A  cast  in  illustration  of  this  is  preserved  in  the  Museum  of  St.  Bartholomew's 
Hospital. 


424  ABDOMINAL   MUSCLES. 

ilium  to  the  skin  of  the  buttock,  without  dividing  like  the  other 
nerves.  The  corresponding  branch  of  the  first  lumbar  has  a 
similar  distribution. 

b.  The  anterior  cutaneous  nerves  emerge  with   small  arteries 
through  the  sheath   of  the    rectus.     They  are  not  only  smaller 
than  the  lateral  nerves,  but  their  number  and  place  of  exit  is  less 
regular. 

c.  The  ilio-hypogastric  nerve  comes  from  the  first  lumbar  nerve, 
pierces  the  transversalis  at  the  iliac  crest,  and  then  divides  into 
an  iliac  and  hypogastric  branch. 

The  iliac  branch  comes  through  both  oblique  muscles,  and  runs 
over  the  crest  of  the  ilium,  behind  the  last  dorsal  nerve,  supplying 
the  integument  over  the  gluteal  muscles. 

The  hypogastric  branch  lies  at  first  between  the  transversalis 
and  internal  oblique ;  then,  piercing  the  latter,  it  runs  forwards 
and  comes  through  the  aponeurosis  of  the  external  oblique,  just 
above  the  external  abdominal  ring,  and  is  distributed  to  the  skin 
in  the  neighbourhood. 

d.  The  ilio-inguinal  nerve,  a  branch  also  of  the  first  lumbar 
nerve,  is  placed  below  the  preceding  nerve,  with  which  it  is  con- 
nected near  the  crest  of  the  ilium.     It  pierces  the  transversalis 
and  internal  oblique,  runs  down  in  the  inguinal  canal  in  front  of 
the  cord,  and  comes  out  through  the  external  abdominal  ring  to 
be  distributed  to  the  skin  of  the  inner  part  of  the  groin,  to  the 
scrotum  and  penis  in  the  male,  and  to  the  labium  pudendi  in  the 
female. 

The  deep  layer  of  the  superficial  fascia  should 
now  be  removed  from  the  external  oblique,  by 
commencing  at  the  fleshy  portion  of  the  muscle,  and  working  in 
the  course  of  its  fibres.  Care  must  be  taken  not  to  remove  any  of 
its  silvery  aponeurosis,  which  is  very  thin,  especially  above.  The 
digitations  of  this  muscle  with  the  serratus  magnus  and  latissimus 
dorsi  must  also  be  made  out. 

MUSCLES  OF  THE        The  abdominal  muscles,  three  on  each  side,  are 
ABDOMINAL  arranged  in  strata,  named,  after  the  direction  of 

WALL,  their  fibres,  the  external  oblique,  internal  oblique, 

and  transversalis.     They  terminate  in  front  in  strong  aponeuroses, 


ABDOMINAL   MUSCLES.  425 

arranged  so  as  to  form  a  sheath  for  a  broad  muscle,  called  the 
rectus,  which  extends  perpendicularly  on  each  side  the  linea  alba 
from  the  sternum  to  the  os  pubis. 

EXTERNAL  This  muscle  arises  from  the  outer  and  lower 

OBLIQUE.  surfaces  of  the  eight  or  nine  lower  ribs,  by  as  many 

pointed  bundles,  called  digitations.1  The  upper  five  of  these  inter- 
digitate  with  similar  bundles  of  the  serratus  rnagnus ;  the  three 
lower  correspond  in  like  manner  with  the  origin  of  the  latissimus 
dorsi ;  but  they  cannot  be  seen  unless  the  body  be  turned  on  the 
side.  The  upper  part  of  this  muscle  descends  obliquely  forwards, 
and  terminates  in  the  aponeurosis  of  the  abdomen ;  the  lower 
proceeds  almost  perpendicularly  from  the  last  ribs,  and  is  in- 
serted into  the  anterior  half  of  the  outer  lip  of  the  crest  of  the 
ilium.2 

The  aponeurosis  of  the  external  oblique  increases  in  strength, 
breadth,  and  thickness,  as  it  approaches  the  lower  margin  of  the 
abdomen,  this  being  the  situation  where  the  greater  pressure  of 
the  viscera  requires  the  most  effective  support.  Its  tendinous 
fibres  take  the  same  direction  as  the  muscle,  and  form  by  their 
decussation  in  the  middle  line  the  linea  alba,  which  extends  from 
the  ensiform  cartilage  to  the  os  pubis.  Above,  the  aponeurosis  be- 
comes much  thinner,  and  is  continued  on  to  the  pectoralis  major 
and  the  ribs.  The  lowest  fibres  are  strong,  and  form  a  thick  border, 
called  Poupart's  ligament. 

The  posterior  border  of  this  muscle  is  fleshy  and  nearly  vertical, 
and  is  overlapped  in  its  upper  half  by  the  latissimus  dorsi. 

The  aponeurosis  is  perforated  by  numerous  cutaneous  vessels 
and  nerves  for  the  supply  of  the  skin  and  subjacent  tissues ;  at  its 
lower  and  inner  aspect,  close  to  the  spine  of  the  os  pubis,  there  is  a 
large  oval  opening  called  the  external  abdominal  ring,  transmitting 
in  the  male  the  spermatic  cord,  and  in  the  female  the  round  liga- 
ment. 

1  The  upper  digitations  are  attached  to  the  ribs  close  to  their  cartilages  ;  the 
lower  ones  to  the  ribs  some  distance  from  the  cartilages ;  the  last  to  the  apex  of 
the  twelfth  rib. 

2  From  its  position  and  the  direction  of   its   fibres,  it  is  manifest  that  the 
external  oblique  represents,  in  the  abdomen,  the  external  intercostal  muscles  of 
the  chest. 


426 


THE   CRURAL   ARCH. 


POUPART'S  Along  the  line  of  junction  of  the  abdomen  with 

LIGAMENT,  OB  the    thigh,    the    aponeurosis    extends    from    the 

CRURAL  ARCH.  anterior  superior  spine  of  the  ilium  to  the  spine 
of  the  os  pubis,  and  forms  an  arch  over  the  intermediate  bony  exca- 
vation (fig.  98).  This,  which  is  termed  the  crural  arch,  or,  more 
commonly,  Poupart's  ligament,1  transmits  the  great  vessels  of  the 
thigh,  with  muscles  and  nerves. 


1.  External    abdominal 

ring. 

2.  Gimbernat's        liga- 

ment. 

3.  Poupart's    ligament, 

or   outer  pillar   of 
the  ring. 


4.  Internal  pillar  of  the 

ring. 

5.  Position  of  the  inter- 

nal ring,  in  dotted 
outline. 


DIAGRAM    OF    POUPART'S   LIGAMENT,    OF    THE   APONEUROSIS   OF    THE    EXTERNAL 
OBLIQUE,    AND    OF    THE    EXTERNAL   ABDOMINAL    RING. 

This  ligament,  when  not  separated  from  its  fascial  connections, 
does  not  run  straight  from  the  spine  of  the  ilium  to  that  of  the  os 
pubis,  but  is  slightly  curved,  with  its  convexity  towards  the  thigh. 
Above,  and  somewhat  to  the  outer  side  of  the  spine  of  the  os  pubis, 
is  situated  an  opening  in  the  aponeurosis,  called  the  external 

1  This  was  first  described  by  Fallopius,  an  Italian  anatomist,  in  his  Observa- 
tiones  Anatomica,  published  in  1561.  It  was  subsequently  described  by  Poupart 
in  1705,  in  the  M6m.  de  VAcad.  de  Paris,  and  is  now  commonly  called  '  Poupart's 
ligament.' 


EXTERNAL   ABDOMINAL  RING.  427 

abdominal  ring.  In  the  male  it  is  a  triangular  opening  about  an 
inch  long,  with  its  base  at  the  os  pubis,  and  will  admit  the  passage 
of  a  finger ;  it  transmits  the  spermatic  cord.  In  the  female  it  is 
smaller,  and  transmits  the  round  ligament  of  the  uterus.  Its  direc- 
tion is  downwards  and  inwards,  and  it  is  bounded  below  by  the  crest 
of  the  os  pubis,  above  by  some  arched  fibres  which  give  strength 
to  the  apex  of  the  opening,  and  on  each  side  by  the  free  margins 
of  the  apo neurosis  which  are  termed  its  columns  or  pillars.  The 
inner  or  upper  pillar  (No.  4  in  the  diagram)  is  thin,  and  is  attached 
to  the  front  of  the  os  pubis,  decussating  with  its  fellow  of  the  opposite 
side  in  front  of  the  symphysis.  The  outer  or  loiver  pillar  is  thicker 
and  stronger,  and  has  three  attachments  :  one,  into  the  spine  of  the 
os  pubis — PouparVs  ligament  (No.  3);  another,  for  three-quarters 
of  an  inch  along  the  linea  ilio-pectinea — Gimbernat's  ligament  (No. 
2) ;  the  third — or  triangular  ligament — consists  of  a  few  fibres 
which  pass  obliquely  upwards  and  inwards  beneath  the  spermatic 
cord  and  the  inner  pillar  as  far  as  the  linea  alba,  where  they 
expand  into  a  triangular  fascia  in  front  of  the  conjoined  tendon, 
and  are  continuous  with  the  aponeurosis  of  the  opposite  side.  At 
the  lower  part  of  the  aponeurosis  of  the  external  oblique,  there  are 
some  arched  fibres  called  inter  columnar  fibres,  which  are  strongest 
above  the  external  ring.  Their  use  is  to  strengthen  the  opening 
and  prevent  the  ring  from  enlarging. 

Attached  to  the  pillars  of  the  external  ring  is  a  thin  fascia,  the 
intercolumnar  Or  external  spermatic  fascia,  which  is  prolonged  over 
the  spermatic  cord  and  testis,  and  thus  forms  one  of  the  coverings 
of  that  organ. 

The  spermatic  cord  in  its  passage  through  the  ring  rests  upon 
the  external  pillar. 

The  external  oblique  should  now  be  detached 
from  the  ribs  and  the  crest  of  the  ilium,  and 
turned  forwards  as  far  as  this  can  be  done  without  injuring  its 
aponeurosis  or  the  crural  arch.  In  detaching  this  muscle  from  the 
ribs,  care  should  be  taken  not  to  reflect  with  it  the  upper  fibres  of 
the  rectus,  and  as  the  dissection  is  carried  forwards,  the  student 
should  avoid  injuring  the  thin  aponeurosis  of  the  internal  oblique 
muscle.  The  second  muscular  stratum  will  thus  be  exposed  and 


428 


INTERNAL   OBLIQUE. 


recognised  by  the  difference  in  the  direction  of  its  fibres,  which 
run  upwards  and  inwards. 

INTERNAL  This  is  thinner  than  the  last-named  muscle,  and 

OBLIQUE.  arises  by  fleshy  fibres  from  the  outer  half  or  more 

of  Poupart's  ligament,  from  the  anterior  two-thirds  of  the  middle 
lip  of  the  crest  of  the  ilium,  and  from  the  posterior  aponeurosis  of 
the  transversalis  muscle  (fascia  lumborum).  The  fibres  radiate  from 
their  origin,  the  anterior  ones  passing  transversely  forwards,  the 
posterior  ones  ascending  nearly  vertically.  The  fibres  are  inserted 

FIG.  99. 


1.  Conjoined  tendon  of 
internal  oblique 
and  transversalis. 


2.  Cremaster  muscle 
passing  down  in 
loops  over  the 
cord. 


DIAGRAM    OF    THE    LOWER   FIBRES    OF    THE    INTERNAL    OBLIQUE    AND    TRANSVERSALIS, 
WITH    THE    CREMASTER    MUSCLE. 

in  the  following  manner :  the  anterior  fibres  (which  arise  from 
Poupart's  ligament)  pass  inwards,  and  arch  over  the  spermatic  cord, 
descending  somewhat  to  be  inserted,  in  common  with  the  tendon 
of  the  transversalis  muscle,  into  the  crest  of  the  os  pubis,  and  for  a 
short  distance  into  the  linea  ilio-pectinea  immediately  behind  the 
external  ring;  the  middle  fibres  (which  arise  from  the  anterior 
iliac  spine  and  front  of  its  crest)  are  directed  transversely  inwards, 
to  be  attached  to  an  aponeurosis  which  passes-  to  the  linea  alba ; 
the  posterior  fibres  ascend  nearly  vertically  to  be  attached  into 


CREMASTER  MUSCLE.  429 

the  cartilages  of  the  four  lower  ribs,  and  are  continuous  with 
the  internal  intercostal  muscles,  which  they  represent  in  the 
abdomen. 

The  aponeurosis  of  the  internal  oblique  is  the  broad  expanded 
tendinous  tissue  into  which  the  muscle  is  anteriorly  attached,  and 
is  continued  to  the  middle  line,  where  its  fibres  join  those  of  the 
opposite  side  at  the  linea  alba.  It  extends  from  the  chest  to  the  os 
pubis,  and  its  fibres  run  in  the  same  direction  as  the  muscle.  At 
the  outer  border  of  the  rectus  it  splits  into  two  layers — an  anterior, 
which  passes  in  front  of  the  rectus  in  conjunction  with  the  aponeu- 
rosis of  the  external  oblique ;  and  a  posterior,  which,  in  common 
with  the  aponeurosis  of  the  transversalis,  passes  behind  the  rectus. 
The  point  of  division  of  the  aponeurosis  presents  a  semilunar  line 
extending  from  the  os  pubis  to  the  cartilage  of  the  eighth  rib.  This 
is  called  the  linea  semilunaris,  through  which  a  hernia  occasionally 
protrudes.  The  two  layers  thus  form  a  sheath  for  the  rectus, 
which,  except  at  the  lower  fourth  behind,  is  complete.  Midway 
between  the  umbilicus  and  the  os  pubis,  the  aponeuroses  of  all  the 
three  muscles  pass  in  front  of  the  rectus,  so  that  posteriorly  in  this 
situation  it  has  no  sheath.  The  lower  free  border  of  the  posterior 
part  of  the  sheath — the  semilunar  fold  of  Douglas — marks  the  situ- 
ation where  the  deep  epigastric  artery  enters  the  substance  of  the 
rectus. 

CREMASTER  The  cremaster  is  a  thin  pale  muscle,  or  the  re- 

MUSCLE.  verse,  according  to  the  condition  of  the  subject. 

It  is  best  to  regard  it  as  a  detachment  of  the  lowest  fibres  of  the 
internal  oblique,  which  arise  from  the  middle  of  Poupart's  ligament. 
Passing  along  the  outer  side  of  the  spermatic  cord,  the  fibres  descend 
with  it  through  the  external  ring,  and  then  arch  up  again  in  front 
of  the  cord  to  the  spine  and  crest  of  the  os  pubis,  forming  loops  of 
different  lengths,  some  reaching  only  as  low  as  the  external  ring, 
others  lower  still,  whilst  the  lowest  spread  out  over  the  tunica 
vaginalis  of  the  testis.  The  muscular  fibres  are  frayed  out,  being 
connected  by  loose  cellular  tissue,  and  form  a  covering  for  the  testis, 
called  the  cremasteric  fascia.  This  muscle  is  absent  in  the  female. 
Its  nerve  comes  from  the  genital  branch  of  the  genito-crural,  and 
its  artery  (cremasteric)  from  the  deep  epigastric. 


430  TRANSVERSALIS   MUSCLE. 

The  student  should  not  now  further  dissect  the 
DISSECTION 

structures  on  the  left  side,  so  that  they  may  be  left 

till  a  future  period  for  the  complete  demonstration  of  the  parts  con- 
cerned in  inguinal  hernia.  On  the  right  side,  the  internal  oblique 
should  be  detached  from  the  ribs  and  the  crest  of  the  ilium,  and 
turned  forwards,  without  disturbing  that  portion  of  it  connected 
with  the  crural  arch.  To  avoid  cutting  away  any  part  of  the  trans- 
versalis  in  reflecting  the  internal  oblique,  dissect  near  the  crest  of 
tlie  ilium,  and  search  for  an  artery  which  runs  between  these 
muscles,  and  may  be  followed  as  a  guide.  This  artery,  called'  the 
deep  circumflexa  ilii,  is  a  branch  of  the  external  iliac,  and  supplies 
the  abdominal  muscles.  Beneath  the  internal  oblique  the  continu- 
ations of  the  intercostal  nerves  and  vessels  are  brought  into  view, 
as  are  also  the  last  dorsal,  the  ilio-hypogastric,  and  ilio-inguinal 
nerves  near  the  crest  of  the  ilium.  These  should  be  preserved. 

The  internal  oblique  is  in  relation,  on  its  deeper  surface  with 
the  transversalis  abdominis,  the  fascia  transversalis,  and  with  the 
spermatic  cord  near  Poupart's  ligament ;  on  its  inner  side,  at  the 
division  of  its  aponeurosis,  with  the  outer  border  of  the  rectus ; 
below,  it  forms  the  upper  arched  boundary  of  the  inguinal  canal. 

TEANSVEKSALIS  This   muscle    arises  by  fleshy  fibres  from  the 

ABDOMINIS.  outer  third  of  Poupart's  ligament,  from  the  ante- 

rior two-thirds  of  the  inner  lip  of  the  crest  of  the  ilium,  from  a 
strong  fascia  attached  to  the  transverse  processes  of  the  lumbar 
vertebras,  and,  lastly,  from  the  inner  surfaces  of  the  six  or  seven 
lower  costal  cartilages,  by  digitations  which  correspond  with  those 
of  the  diaphragm.  From  this  origin  the  fibres  pass  horizontally 
forwards,  and  terminate  anteriorly  in  a  broad  aponeurosis  attached 
to  its  fellow  at  the  linea  alba.  Some  of  its  lower  fibres  arch  down- 
wards, and  are  inserted  with  some  fibres  of  the  internal  oblique  by 
means  of  a  conjoined  tendon  into  the  crest  of  the  os  pubis  and  the 
linea  ilio-pectinea. 

The  aponeurosis  into  which  the  fibres  are  inserted  is  broader 
below  than  above,  and  forms  part  of  the  posterior  sheath  of  the 
rectus,  excepting  in  the  lower  fourth,  where  it  passes  entirely  in 
front. 

In  the  dissection  of  the  back  we  have  fully  described  the  lumbar 


RECTUS    ABDOMINIS. 


431 


fascia,  showing  that  it  divides  into  three  layers  :  the  posterior  layer, 
attached  to  the  tips  of  the  spinous  processes,  gives  attachment 
to  the  internal  oblique,  and  is  continuous  with  the  aponeurosis  of 
the  serratus  posticus  inferior  and  latissimus  dorsi ;  the  middle  layer 
attached  to  the  tips  of  the  transverse  processes,  and  the  anterior 
layer — very  thin — attached  to  the  anterior  aspect  of  the  bases  of 
the  transverse  processes.  Between  the  anterior  and  middle  layer 
is  the  quadratus  lumborum  ;  between  the  middle  and  posterior,  the 
erector  spinas. 

EECTTJS  This  long  muscle  is  situated  vertically  in  front 

ABDOMINIS.  of  the  abdomen,  and  is  enclosed  in  a  sheath  formed 

by  the  aponeuroses  of  the  lateral  muscles  of  the  abdomen,  and 

FIG.  100. 


ERECTOR      SP. 


TRANSVERSE  SECTION  THROUGH  THE  ABDOMINAL  MUSCLES  TO  SHOW  THE 
FORMATION  OF  THE  SHEATH  OF  THE  EECTUS,  THE  QUADBATUS  LUM- 
BORUM, AND  THE  ERECTOR  SPIN.E. 

separated  from  its  fellow  by  the  linea  alba.  To  expose  it,  there- 
fore, slit  up  the  middle  of  the  sheath,  and  reflect  the  two  halves. 
It  arises  by  two  tendons,  the  inner  and  smaller  of  which  is  attached 
to  the  front  of  the  symphysis,  the  outer  to  the  crest  of  the  os  pubis. 
As  the  fibres  pass  up,  the  muscle  becomes  broader  and  thinner, 
and  is  inserted  into  the  fifth,  sixth,  and  seventh  costal  cartilages. 
Notice  the  tendinous  intersections  across  the  muscle  called  linece 
transversce,  which  are  incomplete  repetitions  of  the  ribs  in  the  wall 


432  PYEAMIDALIS. 

of  the  abdomen.1  Their  number  varies  from  three  to  five,  but  there 
are  always  more  above  than  below  the  umbilicus.  These  tendinous 
intersections  adhere  closely  to  the  sheath  in  front,  but  not  behind  ; 
consequently,  pus  formed  between  the  front  of  the  rectus  and  its 
sheath  would  be  confined  by  two  intersections ;  'not  so  on  the  back 
of  the  muscle,  where  pus  might  travel  down  the  entire  length  of  it. 
There  is  one  intersection  on  a  level  with  the  umbilicus,  one  on  a 
level  with  the  ensiform  cartilage,  and  an  intermediate  one  between 
these  two. 

The  sheath  of  the  rectus  consists  in  front  of  the  aponeurosis  of 
the  external  oblique,  and  half  the  thickness  of  that  of  the  internal 
oblique ;  while  the  back  of  the  sheath  comprises  the  aponeurosis 
of  the  transversalis,  and  half  that  of  the  internal  oblique  (fig.  100). 
This,  however,  applies  only  to  the  upper  three-fourths  of  the 
muscle ;  the  lower  fourth  has  no  sheath  behind,  since  all  the 
aponeuroses  pass  in  front  of  it ;  the  only  structure  in  contact  with 
the  muscle  in  this  part  is  the  fascia  transversalis. 

This  small  triangular  muscle  is  situated  near  the 
os  pubis,  close  to  the  linea  alba,  and  has  a  sheath 
of  its  own.  It  arises  by  tendinous  fibres  from  the  front  part  of 
the  os  pubis  and  the  anterior  pubic  ligament  in  front  of  the  rectus, 
and  terminates  in  the  linea  alba  about  midway  between  the  os  pubis 
and  the  umbilicus.  It  is  often  absent  on  one  or  even  both  sides. 

Linea  alba. — The  aponeuroses  of  the  abdominal  muscles  decus- 
sate along  the  middle  line  and  form  a  white  fibrous  band,  extending 
from  the  ensiform  cartilage  to  the  os  pubis.  This  is  the  linea  alba : 
it  is  the  fibrous  continuation  of  the  sternum,  and  is  broader  above 
than  below.  A  little  lower  than  the  middle  is  a  large  aperture  in 
it — the  umbilicus — through  which  a  hernial  protrusion  not  infre- 
quently takes  place.  It  is  in  relation  behind  with  the  fascia  trans- 
versalis, the  urachus,  and  the  bladder  when  distended. 

The  linea  alba,  being  the  thinnest  part  of  the  abdomen,  and 
free  from  large  blood-vessels,  is  chosen  as  a  safe  line  for  tapping  in 
dropsy,  for  puncturing  the  bladder  in  retention  of  urine,  and  for 
ovariotomy. 

Linece  semilunares. — These  are  the  two  slightly  curved  lines, 
1  Some  animals,  e.g.  the  crocodile,  have  bony  abdominal  ribs. 


FUNCTIONS   OF  THE   ABDOMINAL   MUSCLES.  433 

on  the  front  of  the  abdomen,  corresponding  with  the  outer  margins 
of  the  two  recti  muscles.  They  are  formed  by  the  junction  of  the 
aponeuroses  of  the  lateral  muscles. 

The  abdominal  muscles  serve  many  important  purposes : — 
FUNCTIONS  OF  -I8*-  ^-n  tranquil  expiration  they  push  the  dia- 

THE  ABDOMINAL  phragm  upwards  by  gentle  pressure  on  the  abdo- 
MUSCLES.  minal  viscera. 

In  forcible  expiration  the  same  process  takes  place,  but  with 
greater  energy.  This  is  variously  exemplified  in  coughing,  sneezing, 
and  laughing. 

2nd.  In  vomiting,  the  diaphragm  being  fixed  J  by  the  closure 
of  the  glottis,  the  abdominal  muscles  contract,  and  assist  the 
stomach  to  expel  its  contents. 

3rd.  In  conjunction  with  the  contracted  diaphragm,  they  assist 
the  muscular  walls  of  the  bladder  and  rectum  in  the  expulsion  of 
urine  and  faeces,  and  the  action  of  the  uterus  in  parturition.  They 
exercise  a  gentle  pressure  and  support  on  the  abdominal  viscera, 
and  shield  them  from  injury  by  strongly  contracting  when  a  blow 
is  anticipated. 

4th.  They  are  movers  of  the  trunk  in  various  ways.  For  ex- 
ample, the  right  external  oblique  acting  with  the  left  internal 
oblique  will  rotate  the  chest  towards  the  left  side,  as  in  mowing, 
and  vice  versa. 

The  rectus  is  chiefly  concerned  in  raising  the  body  from  the 
horizontal  position,  as  anyone  may  ascertain  by  placing  his  hand 
on  the  abdomen  while  rising  from  the  ground.  The  pyramidalis 
makes  the  linea  alba  tense. 

By  dividing  the  rectus  transversely  near  the 
umbilicus,  and  raising  it  from  its  position,  we 
have  a  complete  view  of  the  manner  in  which  the  sheath  is  formed : 
we  observe,  too,  that  this  is  absent  behind  the  lower  fourth  of  the 
muscle.  Eamifying  in  the  substance  of  the  muscle  is  a  large 
artery,  called  the  deep  epigastric,  a  branch  of  the  external  iliac ; 
also  the  continuation  of  the  internal  mammary,  which  descends 
from  the  subclavian. 

1  By  the  term  '  fixed,'  it  is  meant  that  the  diaphragm  forms  a  resisting  surface. 

F  F 


434  NERVES   OF   THE   ABDOMINAL   WALL. 

NEEVES  OF  THE  These  nerves  are  the  anterior  divisions  of  the 
ABDOMINAL  WALL,  six  lower  intercostal  nerves,  and  of  the  first  lum- 
bar. They  have  the  same  general  course  and  distribution,  and  are 
accompanied  by  small  arteries  derived  from  the  intercostal  and 
first  lumbar  arteries. 

The  intercostal  or  abdominal  nerves  come  forward  beneath  the 
anterior  extremities  of  the  intercostal  spaces,  and  then  run  between 
the  internal  oblique  and  transversalis,  towards  the  edge  of  the 
rectus,  which  they  enter,  small  twigs  coming  through  it  at  the 
middle  line  to  supply  the  skin.  Each  gives  off"  a  lateral  cutaneous 
branch,  which  perforates  the  external  intercostal  and  external 
oblique  muscles,  and  divides,  into  an  anterior  branch — distributed 
to  the  skin  and  superficial  fascia  as  far  as  the  rectus,  and  into  a 
posterior  branch,  smaller  than  the  anterior,  which  supplies  the  skin 
over  the  latissimus  dorsi. 

The  last  dorsal  nerve,  larger  than  the  other  intercostals,  is 
continued  forwards  beneath  the  last  rib,  lying  on  the  quadratus 
lumborum,  and  then  piercing  the  transversalis  aponeurosis,  runs 
between  this  muscle  and  the  internal  oblique,  and  is  finally  distri- 
buted like  the  preceding  nerves.  Its  lateral  cutaneous  branch  is 
very  large,  and  descends  over  the  crest  of  the  ilium. 

The  ilio-hypogastric  nerve,  a  branch  of  the  first  lumbar,  emerges 
from  the  outer  border  of  the  psoas,  and  then  runs  obliquely  across 
the  quadratus  lumborum  as  far  as  the  iliac  crest,  where  it  per- 
forates the  transversalis  muscle  and  divides  into  an  iliac  and  an 
hypogastric  branch  (p.  424). 

The  ilio-inguinal  nerve,  smaller  than  the  former,  and  like  it  a- 
branch  of  the  first  lumbar,  runs  along  the  iliac  crest  after  piercing 
the  psoas,  and  is  here  connected  with  the  ilio-hypogastric.  It 
comes  through  the  transversalis  near  the  front  of  the  ilium,  and, 
after  piercing  the  internal  oblique,  runs  in  front  of  the  cord  in  the 
inguinal  canal.  Its  cutaneous  distribution  has  been  described 
(p.  424). 

The  transversalis  muscle  must  now  be  reflected 

with  the  rectus  by  incisions  similar  to  those  for 

the  reflection  of  the  external  oblique,  when  a  thin  delicate  fascia 

behind,  the  fascia  transversalis,  will  be  exposed.    The  dissection 


FASCIA   TRANS VERSALIS. 


435 


should  take  place  from  below  upwards,  as  the  muscle  is  less  in- 
timately connected  with  the  fascia  below  than  it  is  higher  up. 

FASCIA  TRANS-  This  fascia  separates  the  transversalis    muscle 

VEBSALIS.  from  the  peritoneum,  and  is  so  called  because  it 

lies  in  contact  with  the  posterior  surface  of  the  muscle.  It  is  com- 
paratively thin,  superiorly,  where  it  is  continuous  with  the  fascia 
on  the  under  surface  of  the  diaphragm.  Inferiorly,  it  is  thick  and 
strong,  and  is  attached  to  the  crest  of  the  ilium  and  to  Poupart's 

FIG.  101. 


1.  Internal    abdominal 

ring. 

2.  Position  of  the  ex- 

ternal abdominal 
ring  in  dotted  out- 
line. 

3.  Epigastric      a.      in 

dotted  outline. 


4,  4.  Sheath  of  the  fem- 
oral vessels,  con- 
tinued from  the 
fascia  transver- 
salis. 

5.  Femoral  a. 

6.  Profunda  a. 

7.  Saphena  v. 

8,  8.  Fascia  transver- 
salis. 


DIAGRAM   OF   THE   FASCIA   TRANSVERSALIS   SEEN   FROM   THE   FRONT. 

ligament,  where  it  is  strengthened  by  fibres  from  the  aponeurosis 
of  the  transversalis ;  it  becomes  continuous  with  the  fascia  covering 
the  iliacus  muscle  (iliac  fascia),  and  below  with  the  pelvic  fascia. 
About  the  middle  of  Poupart's  ligament  it  sends  a  funnel-shaped 
prolongation  downwards  into  the  thigh,  forming  the  anterior  part 
of  the  sheath  of  the  femoral  vessels.  Internally,  it  is  connected 
with  the  margin  of  the  rectus,  to  the  lower  margin  of  the  conjoined 
tendon,  to  the  os  pubis,  and  to  the  pectineal  line.  This  fascia  is 


436  INTERNAL  ABDOMINAL  RING. 

strongest  just  behind  the  external  abdominal  ring,  and,  but  for  it 
and  the  conjoined  tendon,  there  would  be  a  direct  opening  into 
the  abdominal  cavity  through  the  external  ring.  The  outer  half  of 
the  fascia  is  very  firmly  connected  to  Poupart's  ligament  and  to 
the  fascia  iliaca ;  but  the  inner  half  is  loosely  connected  with  the 
crural  arch,  and  passes  down  under  it,  as  before  stated,  over  the 
femoral  vessels  into  the  thigh,  and  forms  the  front  of  what  is 
termed  the  crural  sheath. 

INTEENAL  AB-  The  opening  in  the  fascia  transversalis  through 

DOMINAL  EING.  which  the  spermatic  cord  passes  is  called  the 
internal  abdominal  ring  (or  the  inner  aperture  of  the  inguinal 
canal),  It  corresponds  to  a  point  midway  between  the  anterior 
superior  spine  of  the  ilium  and  the  spine  of  the  os  pubis,  and 
about  half  an  inch  above  Poupart's  ligament.  It  is  oval  with  the 
long  diameter  nearly  vertical ;  it  is  bounded  above  by -the  arched 
fibres  of  the  trausversalis  muscle,  and  on  the  inner  side  by  the 
deep  epigastric  vessels.  Its  margin  is  well  defined  on  the  inner, 
but  not  on  the  outer  side,  and  from  its  border  is  continued  for- 
wards a  funnel-shaped  prolongation  over  the  spermatic  cord,  which 
passes  through  the  ring.  This  covering,  thin  and  delicate,  is  termed 
the  infundibuliform  fascia.  (This  is  not  seen  in  the  diagram.) 
Close  by  the  inner  border  of  the  internal  ring,  the  deep  epigastric 
artery  ascends  to  enter  the  substance  of  the  rectus. 

AETEEIES  OF  The  abdominal  walls  are  supplied  with  blood 

THE  ABDOMINAL  derived  from  the  intercostal,  lumbar,  and  deep 
WALLS-  circumflex  iliac  arteries,  and,  in  front  also,  from 

the  internal  mammary  and  deep  epigastric  arteries. 

The  intercostal  arteries  come  from  the  descending  thoracic  aorta, 
and,  like  their  accompanying  nerves,  enter  the  abdominal  wall 
between  the  transversalis  and  internal  oblique  muscles.  They 
anastomose  with  the  internal  mammary,  deep  epigastric,  and  lumbar 
arteries. 

The  lumbar  artery  accompanies  the  last  dorsal  nerve. 

The  internal  mammary  artery  divides,  between  the  cartilages 
of  the  sixth  and  seventh  ribs,  into  the  musculo-phrenic  and  the 
superior  epigastric  arteries.  The  superior  epigastric  artery  de- 
scends behind  the  cartilage  of  the  seventh  rib,  and,  piercing  the 


ARTERIES   OF   THE   ABDOMINAL   WALLS.  437 

sheath  of  the  rectus,  enters  that  muscle,  supplying  it  and  anasto- 
mosing with  the  deep  epigastric. 

The  musculo-pTirenic  artery  descends  obliquely  outwards  be- 
hind the  cartilages  of  the  false  ribs,  and  pierces  the  diaphragm 
about  the  ninth  rib ;  it  is  then  continued  along  the  last  intercostal 
space,  and  terminates  in  branches  for  the  supply  of  the  abdominal 
walls. 

The  deep  epigastric  artery  arises  from  the  external  iliac,  just 
before  this  vessel  passes  under  the  crural  arch  to  take  the  name  of 
femoral.  It  ascends  inwards  between  the  fascia  transversalis  and 
the  peritoneum,  forms  a  gentle  curve  on  the  inner  side  of  the  internal 
abdominal  ring,  and  consequently  on  the  inner  side  of  the  spermatic 
cord,  and  then  enters  the  rectus  muscle  just  below  the  fold  of 
Douglas,  which  is  the  lower  arched  edge  of  the  posterior  sheath  of 
the  rectus. - 

The  artery  runs  in  the  substance  of  the  rectus  parallel  with  the 
linea  alba,  and  inosculates  with  the  superior  epigastric  branch  of 
the  internal  mammary  artery.  It  is  accompanied  by  two  veins,  of 
which  the  larger  is  on  its  inner  side ;  these  terminate  in  a  single 
trunk  in  the  external  iliac  vein. 

The  deep  epigastric  gives  off  the  following  branches  : — 

The  pubic  is  the  most  important  branch.  It  runs  inwards, 
behind  the  crural  arch,  towards  the  os  pubis,  behind  which  it  ana- 
stomoses with  the  pubic  branch  of  the  obturator.  Sometimes  the 
obturator  artery  is  absent  or  small,  in  which  case  the  pubic  branch 
of  the  epigastric  enlarges  and  takes  the  place  of  the  absent  vessel. 
It  derives  its  chief  practical  interest  from  the  fact  that  it  is  liable 
to  be  wounded  in  dividing  the  stricture  in  femoral  hernia.1  But 
its  size  varies  in  different  subjects,  and  is  sometimes  so  small  as 
to  escape  observation.  The  second  branch  is  the  cremasteric.  It 
supplies  the  coverings  of  the  cord,  but  chiefly  the  cremaster  muscle. 
After  giving  off  other  unnamed  muscular  branches,  some  of  which 
perforate  the  muscle  to  supply  the  skin,  the  main  trunk  terminates 
in  the  rectus  by  inosculations  with  the  internal  mammary. 

1  There  is  a  preparation  in  the  Museum  of  St.  Bartholomew's  Hospital  quite  to 
the  point.  The  patient  had  profuse  hasmorrhage,  which  commenced  five  hours 
after  the  operation.  He  died  from  peritonitis. 


438  THE   INGUINAL   CANAL. 

DEEP  CIKCUM-  The  deep  circumflexa  ilii  artery  is  a  branch  of 

FLEXA  ILII.  the  external  iliac,  just  above  the  crural  arch  ;  it 

runs  upwards  and  outwards,  behind  and  parallel  with  Poupart's 
ligament,  and  at  the  middle  of  the  crest  of  the  ilium  pierces  the 
transversalis  muscle,  and,  running  in  the  same  direction,  lies  be- 
tween the  transversalis  and  internal  oblique.  It  anastomoses  with 
the  ilio-lumbar  artery,  and  sends  small  muscular  branches,  which 
run  upwards,  and  communicate  with  the  epigastric  and  the  lumbar 
arteries. 

The  circumflex  iliac  veins  join  to  form  a  single  vein,  which 
crosses  the  external  iliac  artery,  and  opens  into  the  external  iliac 
vein. 

To  see  that  part  of  the  peritoneum  concerned  in 
DISSECTION.  .         .  .        ,       „      . 

inguinal  hernia,  the  fascia  transversalis  must  be 

removed  by  incisions  similar  to  those  recommended  before.  The 
fascia  is  easily  separable  from  the  peritoneum  which  is  situated 
immediately  behind  it,  owing  to  the  presence  of  more  or  less  fat — 
subperitoneal  fat.  The  peritoneum  at  the  inner  ring  presents  a 
well-marked  depression,  which  varies,  however,  considerably :  in 
some  being  scarcely  visible ;  in  others,  being  continued  downwards 
into  the  inguinal  canal,  in  the  form  of  a  pouch.  In  some  instances, 
a  communication  is  found  between  the  general  cavity  of  the  peri- 
toneum and  the  tunica  vaginalis  testis. 

INGUINAL  Having   examined   the  several  strata  through 

CANAL.  which  the  spermatic  cord  passes,  replace  them  in 

their  natural  position,  and  examine  the  inguinal  canal  as  a  whole. 
Its  direction  is  obliquely  downwards  and  inwards.  Its  length 
in  a  well-formed  adult  male  is  from  one  and  a  half  to  two  inches. 
It  commences  at  the  inner  ring,  and  terminates  at  the  external 
abdominal  ring.  It  is  bounded  in  front  by  skin,  superficial  and 
deep  fasciae,  by  the  aponeurosis  of  the  external  oblique,  and  ex- 
ternally by  a  small  portion  of  the  internal  oblique ;  behind,  by 
the  fascia  transversalis,  by  the  conjoined  tendon  of  the  internal 
oblique  and  transversalis,  and  by  the  triangular  ligament ;  above, 
by  the  lower  fleshy  fibres  of  the  internal  oblique  and  transversalis ; 
below,  by  the  junction  of  the  fascia  transversalis  with  the  crural 
arch. 


SPERMATIC   CORD.  439 

SPERMATIC  This  round  cord  extends  from  the  testis  to  the 

CORD.  internal  abdominal  ring,  and  consists  of  numerous 

structures,  connected  together  by  delicate  areolar  tissue,  and  is  sur- 
rounded by  the  different  strata  from  the  abdominal  muscles,  which 
are  pushed  down  in  the  descent  of  the  testis  into  the  scrotum  in  foetal 
life.  The  cord  lies  in  the  inguinal  canal ;  at  the  outer  ring  it  rests 
on  the  outer  pillar,  and  at  the  inner  ring  the  different  constituents 
of  the  cord  separate  from  each  other. 

The  arteries  of  the  cord  are  derived  from  the  spermatic  artery 
from  the  abdominal  aorta,  the  deferential  artery  from  the  superior 
vesical,  and  the  cremasteric  branch  from  the  deep  epigastric. 

The  veins  of  the  cord  are  chiefly  the  spermatic :  they  form  on 
the  cord  a  plexus  of  veins — the  pampiniform  plexus — and,  passing 
up  in  front  of  the  cord,  open  on  the  right  side  into  the  inferior 
vena  cava ;  and  on  the  left  side,  into  the  left  renal  vein. 

The  lymphatics  pass  into  the  lumbar  glands. 

The  nerves  are  derived  from  the  renal,  aortic,  and  hypogastric 
plexuses.  In  front  of  the  cord  is  the  ilio-inguinal  nerve,  and  behind 
it,  is  the  genital  branch  of  the  genito-crural  nerve. 

The  cord,  as  will  presently  be  described,  receives  coverings  from 
the  external  oblique,  from  the  internal  oblique  and  transversalis, 
and  from  the  fascia  transversalis. 

The  vas  deferens,  the  excretory  duct  of  the  testis,  passes  through 
the  inguinal  canal,  being  placed  behind  the  other  constituents  of  the 
cord,  and,  after  passing  through  the  inner  ring,  curves  round  the 
epigastric  artery  in  its  descent  into  the  pelvis. 

BOUND  LIGA-  In  the  female  there  is  a  round  cord  occupying 

MENT.  the  inguinal  canal — the  round  ligament — which  is 

lost,  external  to  the  outer  ring,  in  the  subcutaneous  tissues  of  the 
labium  majus.  Its  coverings  are  the  same  as  those  of  the  male, 
excepting  the  cremasteric  fascia. 

DEEP  CBURAL  This  structure,  which  is  apparently  a  thickening 

ARCH.  of  the  fascia  transversalis,  has  more  to  do  with 

femoral  hernia,  and  its  description  will,  therefore,  be  deferred  until 
this  form  of  hernia  is  considered  in  the  dissection  of  the  thigh. 


440  PARTS   CONCERNED   IN   INGUINAL    HERNIA. 

DISSECTION   OF   THE   PAETS   CONCEENED   IN   INGUINAL   HEENIA. 

The  student  has  now  completed  the  dissection 
on  the  right  side,  and,  having  mastered  the  general 
anatomy  of  this  region,  he  may  pass  on  to  the  special  consideration 
of  the  anatomy  of  inguinal  hernia.  If  the  instructions  before  given 
have  been  duly  observed,  the  left  side  is  available  for  this  purpose  ; 
and,  although  it  may  be  well  that  the  dissector  (especially  for  the 
first  time)  should  have  the  advantage  of  the  parts  being  made  clear 
by  his  demonstrator,  there  is  no  real  difficulty  in  making  out  the 
different  layers  which  constitute  the  coverings  of  a  hernia,  or  the 
various  parts  through  which  a  hernia  travels. 

It  will  be  remembered  that  on  the  left  side  the  dissection  has 
been  carried  as  far  as  the  exposure  of  the  internal  oblique  and 
ere  master.  An  incision  must  now  be  made  through  the  external 
oblique,  from  a  point  midway  between  the  umbilicus  and  the  os 
pubis,  transversely  outwards  to  the  anterior  superior  iliac  spine,  and 
another  from  the  same  point  downwards  in  the  middle  line  through 
the  linea  alba  as  far  as  the  symphysis  pubis.  When  this  flap  has 
been  turned  downwards,  the  dissector  will  see  that  it  is  aponeurotic, 
and  he  can  take  the  opportunity  of  making  out  the  external  abdo- 
minal ring  and  the  external  spermatic  fascia  which  is  prolonged 
downwards  from  the  pillars  of  the  ring,  as  also  the  intercolumnar 
bands  which  strengthen  the  upper  part  of  the  ring. 

The  internal  oblique  now  comes  into  view,  and  its  origin  from 
Poupart's  ligament  must  be  carefully  made  out,  together  with  the 
cremaster  muscle,  which -loops  in  front  of  the  cord,  and  which  can 
be  seen  coming  under  the  arched  fibres  of  this  muscle.  Next, 
the  internal  oblique  should  be  reflected  from  Poupart's  ligament 
and  the  iliac  crest  by  a  transverse  incision  to  the  extent  of 
that  through  the  external  oblique.  The  flap  should  then  be  re- 
flected inwards,  care  being  taken  not  to  reflect  with  it  the  sub- 
jacent muscle  (transversalis)  ;  this  may  be  prevented  by  looking 
for  a  branch  of  the  deep  circumflex  iliac  artery,  which  runs  along 
the  crest  of  the  ilium  between  these  muscles.  The  turning  back 


PARTS   CONCERNED    IN   INGUINAL   HERNIA.  441 

of  this  muscle  exposes  the  tranversalis,  which  in  its  turn  will  be 
reflected  inwards  in  the  same  manner.  The  inner  parts  of  both 
these  muscles  are  intimately  connected  by  a  common  tendon,  called 
the  conjoined  tendon,  inserted  in  front  of  the  rectus  into  the  crest 
of  the  os  pubis  and  the  pectineal  line.  Observe  that  this  tendon  lies 
immediately  behind  the  external  abdominal  ring,  and  that  it  varies 
in  thickness  in  different  subjects.  The  arching  over  of  the  lower 
fibres  of  the  internal  oblique  and  transversalis,  so  as  to  form  the 
upper  boundary  of  the  inguinal  canal,  are  now  well  seen. 

Reflect  the  transversalis  exactly  in  the  same  way  as  the  internal 
oblique,  when  the  fascia  transversalis  comes  into  view,  presenting 
the  funnel-shaped  prolongation  of  fascia — infundibuliform — which 
is  continued  over  the  cord  and  testis. 

The  transversalis  fascia  should  now  be  detached  from  the  sub- 
jacent peritoneum,  in  front  of  which  is  more  or  less  fat  (s«5- 
peritoneal),  and  turned  down,  when  the  internal  abdominal  ring 
becomes  apparent,  with  its  well-defined  inner  margin. 

During  the  reflection  of  these  successive  muscles,  the  student 
will  have  been  enabled  to  recognise  the  strata  which  are  prolonged 
from  them  :  viz.,  from  the  external  oblique  is  derived  the  spermatic 
fascia ;  from  the  internal  oblique  and  transversalis  is  derived  the 
cremasteric  fascia ;  and  from  the  fascia  transversalis  is  prolonged 
the  transversalis  fascia,  which  here  takes  the  name  of  the  infundi- 
buliform fascia. 

The  extent  and  boundaries  of  the  inguinal  canal  and  the  rela- 
tion of  the  epigastric  artery  to  the  inner  ring  can  now  be  clearly 
defined;  and  if  the  dissector  passes  his  little  finger  into  the 
internal  abdominal  ring,  down  the  canal  and  out  through  the 
external  ring,  he  will  easily  see  that  it  carries  before  it  the  three 
strata  previously  described,  which  constitute  not  only  the  coverings 
of  the  cord,  but  likewise  the  coverings  '  of  an  oblique  inguinal 
hernia,  when  this  exists. 

PKACTICAL  The  testis,  originally  formed  in  the  loins,  passes, 

APPLICATION.  about  the    eighth  month  of  foetal  life,  from  the 

abdomen  into  the  scrotum,  through  an  oblique  canal  in  the  wall 

1  In  the  case  of  a  hernia  there  is  necessarily  in  addition  a  covering  of  sub- 
peritoneal  fat,  and  of  peritoneum  which  forms  the  sac. 


442  PARTS   CONCERNED   IN   INGUINAL   HERNIA. 

of  the  abdomen,  called  the  inguinal  canal.  A  portion  of  peri- 
toneum is  pouched  out  before  the  descending  testis,  and  consti- 
tutes the  tunica  vaginalis  testis.  The  blood-vessels,  nerves,  and 
vas  deferens  are  drawn  down  with  the  testis,  and  constitute  the 
spermatic  cord.  The  inguinal  canal  runs  obliquely  through  the 
abdominal  wall,  that  it  may  the  better  resist  the  protrusion  of 
intestine. 

The  wall  of  the  abdomen,  as  previously  stated,  is  composed  of 
various  strata,  and  the  testis  and  cord  in  their  passage  through 
each  stratum  derive  from  each  a  covering  similar  in  structure  to 
the  stratum  itself.  Of  these  strata  there  are  three :  the  first,  pro- 
ceeding from  within  outwards,  is  the  fascial  stratum  derived  from 
the  fascia  transversalis ;  the  second  is  the  muscular  stratum  (cre- 
masteric)  from  the  internal  oblique  and  transversalis  muscles ;  the 
third  is  the  aponeurotic  stratum  from  the  external  oblique. 

The  passage  of  the  testis  through  the  lower  part  of  the  ab- 
dominal parietes  (inguinal  canal)  occasions,  at  this  part  of  the 
belly,  a  natural  weakness  which,  associated  with  other  conditions, 
favours  the  protrusion  of  intestine  in  this  situation. 

A  protrusion  of  intestine  through  any  part  of  the  inguinal 
canal  is  called  an  inguinal  hernia :  of  which,  two  chief  varieties 
exist,  the  indirect  or  oblique,  and  the  direct ;  the  former  protrud- 
ing to  the  outer  side  of  the  deep  epigastric  artery ;  the  latter 
coming  out  to  the  inner  side  of  the  artery. 

OBLIQUE  The  most  common  form  of  inguinal  hernia  is 

INGUINAL  HERNIA,  that  in  which  a  portion  of  intestine  protrudes 
first  through  the  internal  ring,  then,  traversing  the  inguinal  canal, 
emerges  through  the  external  ring,  and  thence  may  descend  into 
the  scrotum.  This  variety  is  called  an  oblique  inguinal  hernia.1 
If  the  intestine  stops  within  the  inguinal  canal,  it  is  called  an  in- 
complete inguinal  hernia ;  if,  however,  the  protrusion  has  emerged 
through  the  external  ring,  it  is  called  a  complete  inguinal  hernia ; 
and,  lastly,  if  it  descends  into  the  scrotum,  it  is  called  a  scrotal 
hernia. 

1  A  hernia  is  sometimes  called  external  or  internal,  according  to  the  relation 
of  the  protrusion  to  the  deep  epigastric  artery :  thus,  an  oblique  inguinal  hernia 
which  first  protrudes  through  the  inner  ring  is  called  an  external  hernia,  and 
vice  versa. 


OBLIQUE   AND   DIRECT   INGUINAL   HERNIA.  443 

COVERINGS  OF  A-  complete  oblique  inguinal  hernia,  passing  as 

AN  OBLIQUE  IN-  it  does  through  the  same  structures  as  the  testis 
GUINAL  HERNIA.  ^j^  jn  f^al  }if6j  receives  the  same  coverings  as 
that  gland ;  they  are  : — 

1.  The  skin  and  the  superficial  fascia. 

2.  The  intercolumnar  fascia,  derived  from  the  external  oblique. 

3.  The  cremaster,  derived  from  the  internal  oblique  and  transversalis. ' 

4.  The  infundibuliform  fascia,  derived  from  the  fascia  transversalis. 

5.  The  subperitoneal  fat,  and  the  peritoneum  which  constitutes  the 
sac. 

An  incomplete  oblique  inguinal  hernia  is  covered  by — 

1.  The  shin  and  superficial  fascia. 

2.  The  aponeurosis  of  the  external  oblique. 

3.  The  cremaster. 

4.  The  infu ndibidiform  fascia. 

5.  The  stibperitonealfat  and  the  peritoneum. 

DIRECT  INGUI-  The  intestine,  however,  does  not  always  escape 

NAL  HERNIA.  through  the  internal  ring.  Sometimes  it  pro- 

trudes internal  to  the  deep  epigastric  artery  through  a  triangular 
weak  place,  HesselbacJis  triangle,  bounded  on  the  inner  side  by  the 
rectus,  on  the  outer  side  by  the  deep  epigastric  artery,  and  below 
by  Poupart's  ligament.  This  space  is  relatively  weak,  having  in 
front  of  it  only  the  fascia  transversalis  and  the  conjoined  tendon  of 
the  internal  oblique  and  transversalis ;  moreover,  it  is  situated 
immediately  behind  the  external  abdominal  ring.  A  portion  of 
intestine  protruding  through  this  triangle  comes  directly  forwards 
through  the  external  ring,  and  the  hernia  is  then  called  a  direct 
inguinal  hernia. 

COVERINGS  OF  A  A-  direct  inguinal  hernia  protrudes  immediately 
DIRECT  INGUINAL  on  the  inner  side  of  the  epigastric  artery  through 
HERNIA.  fae  external  ring ;  and  its  course  forwards  is 

mainly  prevented  by  the  resistance  of  the  conjoined  tendon.2  This 
hernia  is  covered  by — 

1  The  cremaster  muscle  is  absent  in  the  female. 

z  In  our  experience  the  weakness  of  the  conjoined  tendon  is,  anatomically 
speaking,  the  determining  cause  of  this  form  of  hernia. 


444  CONGENITAL  INGUINAL   HERNIA. 

1.  The  skin  and  superficial  fascia. 

2.  The  intercolumnar  fascia. 

3.  The  conjoined  tendon  of  the  internal  oblique  and  transversalis. 

4.  The  fascia  transversalis. 

5.  The  subperitonealfat  and  the  peritoneum. 

A  direct  hernia,  as  has  been  said,  emerges  through  Hesselbach's 
triangle,  and  if  this  triangle  be  viewed  from  its  deeper  aspect, 
it  will  be  seen  that,  usually,  the  obliterated  hypogastric  artery 
corresponds  in  its  course  to  the  deep  epigastric  artery.  Occa- 
sionally, however,  it  is  placed  further  inwards,  so  that  it  divides  the 
triangle  into  two  smaller  ones,  in  both  of  which  there  is  a  shallow 
pouching  of  peritoneum.  Now,  if  a  direct  hernia  protrudes 
through  the  outer  of  these  two  smaller  triangles,  it  descends 

FIG.  102. 


VARIETIES  OF  CONGENITAL  INGUINAL  HERNIA,  CONSEQUENT  UPON  SOME  DEFECT  IN  THE 
DEVELOPMENT  OF  THE  SPERMATIC  PORTION  OF  THE  TUNICA  VAGINALIS.  THE 
ARROWS  MARK  THE  PROTRUSION. 

1.  Hernia  in  the  tunica  vaginalis  testis.  3.  Infantile  hernia. 

2.  Hernia  in  the  funicular  portion  of  the  tunica  4.  Encysted  hernia. 

vaginalis. 

through  the  inguinal  canal,  and  thus  will  have  all  the  coverings  of 
an  ordinary  oblique  inguinal  hernia. 

In  almost  all  cases,  the  immediate  investment  of  the  intestine 
is  the  parietal  layer  of  the  peritoneum.  This  constitutes  the  sac 
of  the  hernia.  The  opening  of  the  sac,  communicating  with  the 
abdomen,  is  called  its  mouth ;  then  comes  the  narrow,  constricted 
portion,  or  neck ;  and  lastly,  the  body,  or  expanded  part  of  the  sac. 
CONGENITAL  Owing  to  the  comparatively  late  descent  of  the 

HERNIA.  testis  in   fcetal   life,  it   frequently  happens   that 


CONGENITAL   INGUINAL   HERNIA.  445 

either  no  closure,  or  only  a  partial  closure,  takes  place  in  the 
vaginal  portion  of  the  tunica  vaginalis.  Under  these  conditions, 
when  a  protrusion  takes  place,  the  intestine  does  not  push  forwards 
a  sac  derived  from  the  parietal  layer  of  the  peritoneum,  but  it  lies 
in  a  sac  formed  by  the  tunica  vaginalis,  which  still  communicates 
with  the  peritoneal  cavity.  These  hernias  are  always  oblique,  and 
are  termed  congenital.1  There  are  four  varieties,  all  of  which  are 
the  result  of,  or  associated  with,  some  congenital  defect.  They  are 
as  follows  : — 

1.  Hernia  in  the  tunica  vaginalis  testis. — This  occurs  when  a  protru- 
sion of  intestine  takes  place  through  the  narrow  canal  which  persists 
between  the  general  cavity  of  the  peritoneum  and  the  tunica  vaginalis 
testis,  in  consequence  of  the  non-obliteration  of  the  original  communica- 
tion between  them.     In  this  case,  the  intestine  surrounds  the  testis,  and 
the  sac  is  formed  by  the  tunica  vaginalis  testis  (fig.  102,  I).2 

2.  Hernia  in  the  funicttlar  portion  of  the  tunica  vaginalis  occurs 
when  an  incomplete  closure  of  the  tunica  vaginalis  takes  place  imme- 
diately above  the  testis  ;  the  canal  above  it  being  still  unclosed  and 
communicating  with  the  peritoneal  cavity.     The  sac  is  formed  by  the 
original  pouch  of  the  peritoneum  in  the  descent  of  the  testis,  although 
shut  off  from  the  tunica  vaginalis  testis  by  a  thin  septum  (fig.  102,  2). 

3.  Infantile  hernia  is  rare,  and  occurs  when  the  original  peritoneal 
canal  is  occluded  at  the  inner  ring,  so  that  the  tunica  vaginalis  testis 
reaches  up  as  high  as  the  canal,  or  even  as  far  as  the  internal  ring.    The 
intestine  in  this  variety  protrudes  a  sac  through  the  inner  ring,  but 
behind  this  abnormal  extension  of  the  tunica  vaginalis  ;  so  that   in 
front  of  the  hernia  there  are  three  layers  of  peritoneum  :  two  formed 
by  the  tunica  vaginalis,  the  third  by  the  sac  (fig.  102,  3). 

4.  Encysted  hernia  is  still  rarer  than  the  preceding,  and  may  occur 
in  those  cases  in  which  the  closing  septum    at  the   internal  ring   is 
so  thin  that  an  advancing  hernia  pushes  before  it  this  thin  stratum 
(which  forms  its  sac)  as  a  diverticulum  into  an  unclosed  tunica  vaginalis 
(fig.  102,  4). 

1  The  term  congenital  applied  to  this  form  of  hernia  is  apt  to  suggest  the  idea 
that  it  occurs  at  birth.  But  this  is  not  of  necessity  so.   Although  the  state  of  parts 
favourable  to  its  occurrence  exists  at  birth,  the  hernia  itself  may  not  take  place 
till  many  years  afterwards — in  fact,  at  any  period  of  life. 

2  A  good  specimen  of  this  variety,  prepared  by  Percival  Pott,  is  in  the  Museum 
of  St.  Bartholomew's  Hospital. 


446  UMBILICAL   HERNIA. 

POSITION  OP  The  spermatic  cord  is  generally  situated  behind 

SPERMATIC  COED.  and  to  the  outer  side  of  a  hernial  sac.  In  some 
cases,  however,  the  hernia  separates  the  constituents  of  the  cord, 
so  that  one  or  other  of  these  comes  to  lie  in  front  of  the  protrusion. 

SEAT  OF  The  stricture  may  be  seated  either  at  the  ex- 

STRICTURE.  ternal  ring,  the  internal  ring,  at  any  intermediate 

part  between  these,  or  at  the  neck  of  the  sac.  Sometimes  there  is  a 
double  stricture,  one  at  the  external  ring,  the  other  at  the  internal. 
As  stated,  the  stricture  may  be  caused  by  the  neck  of  the  sac, 
independently  of  the  parts  outside  it ;  for  the  peritoneum  may 
become  thickened  and  indurated,  and  sufficiently  unyielding  to 
strangulate  the  protruded  intestine.  The  strangulation  in  a  con- 
genital hernia  is  nearly  always  caused  by  the  neck  of  the  sac  itself. 
In  dividing  the  stricture,  the  surgeon  should,  in  all  cases, 
adhere  to  the  golden  rule  laid  down  by  Sir  Astley  Cooper — namely, 
to  divide  it  directly  upwards.  In  this  direction,  there  is  the  least 
likelihood  of  wounding  the  deep  epigastric  artery. 

CHANGES  PRO-  Whoever  has  the  opportunity  of  dissecting  an 

DUCED  BY  AN  OLD  old  hernia  of  some  size,  will  observe  that  the 
AND  LARGE  obliquity  of  the  inguinal  canal  is  destroyed.  The 

HERNIA.  constant  dragging  of  the  protruded  viscera  upon 

the  inner  margin  of  the  internal  ring  gradually  approximates  the 
internal  ring  to  the  external,  so  that  at  last  the  one  gets  quite 
behind  the  other,  and  there  is  a  direct  opening  into  the  abdomen. 
But  the  position  of  the  deep  epigastric  artery  with  regard  to  the 
sac  remains  unaltered.  It  is  still  on  the  inner  side  of  the  neck  of 
the  sac. 

In  hernige  of  long  standing,  all  its  coverings  undergo  a  change. 
They  become  thickened  and  hypertrophied,  and  so  altered  from 
what  they  once  were  that  they  scarcely  look  like  the  same  parts. 

UMBILICAL  This  is  a  hernia  which  protrudes  through  the 

HERNIA.  umbilical  opening  in  the  middle  line  at  the  um- 

bilicus, and  is  most  commonly  met  with  in  infant  life,  and  in  the 
female  sex  in  advanced  life,  especially  in  obese  subjects.  The 
hernia  is  frequently  large,  and,  in  its  enlargement,  it  increases  in 
an  upward  direction,  so  that  the  aperture,  through  which  it  comes, 
is  not  in  the  centre  of  the  hernia. 


VENTRAL    HERNIA.  447 

Its  coverings  are  skin,  subcutaneous  fat  and  connective  tissue, 
a  thin  fascia  which  covers  in  the  umbilical  aperture,  fascia  trans- 
versalis,  subperitoneal  fat,  and  peritoneum. 

The  seat  of  strangulation  in  this  variety  of  hernia  is  the  fibrous 
margin  of  the  umbilical  aperture.  This  must  be  divided,  and, 
as  there  are  no  vessels  or  other  structures  of  importance  near  it, 
the  margin  may  be  divided  at  any  part  most  convenient  to  the 
operator.  Owing  to  the  size  which  umbilical  hernia?  frequently 
attain,  it  is  not  always  easy  to  divide  the  constricting  margin,  and 
great  care  is  needed  to  prevent  the  intestines  being  injured  during 
the  operation. 

VEKTBAL  This  term  is  applied  to  those  forms  of  hernia 

HEBNI.E.'  which  protrude  through  the  abdominal  walls  in 

situations  not  included  in  the  inguinal  and  umbilical  varieties. 
The  most  common  variety  is  that  which  comes  through  the  linea 
alba,  usually  above  the  umbilicus.  They  are  small  and  mushroom- 
shaped,  with  narrow  pedicles,  and  are  commonly  irreducible.  In 
some  cases,  these  protrusions  are  masses  of  subperitoneal  fat  emerging 
through  foramina  in  the  linea  alba,  growing  after  they  protrude ; 
so  that  these  are  not  hernias  in  the  strict  sense  of  the  term. 
Ventral  hernias  occasionally  come  through  the  linea  semilunaris ; 
others  come  through  the  triangular  interval  between  the  latissimus 
dorsi  and  posterior  free  border  of  the  external  oblique,  and  are 
termed  lumbar  hernice.  There  is,  in  fact,  no  part  of  the  abdominal 
walls  through  which  a  hernia  may  not  protrude. 

Expose  the  contents  of  the  abdomen,  by  an  in- 
cision from  the  ensiform  cartilage  to  the  os  pubis  a 
little  to  the  left  side  of  the  linea  alba,  so  as  to  preserve  a  ligament, 
ligamentum  teres,  which  passes  from  the  umbilicus  to  the  liver, 
and  also  a  cord,  the  urachus,  which  ascends  in  the  middle  line 
from  the  bladder  to  the  umbilicus ;  then  make  another  incision 
transversely  on  a  level  with  the  umbilicus,  and  turn  the  flaps 
outwards. 

Behind  the  linea  alba,  the  peritoneum  is  raised 

into  a  fold  by  a  fibrous  cord,  passing  from  the 

bladder  to  the  umbilicus :  this  is  the  urachus,  which  in  foetal  life 

is  a  tube  connecting  the  bladder  with  the  allantois.     On  either 


448       STRUCTURES  SEEN  ON  OPENING  THE  ABDOMEN. 

side  of  the  urachus  are  two  other  folds,  enclosing  cords  which 
ascend  obliquely  towards  the  umbilicus :  these  are  the  impervious 
remains  of  the  Jiypogastric  arteries. 

On  opening  the  cavity  of  the  peritoneum,  there  are  seen,  in  con- 
nection with  the  fibrous  cords  just  mentioned,  two  fossae  in  the  neigh- 
bourhood of  Poupart's  ligament — one  on  the  inner  side,  the  other 
on  the  outer  side  of  the  obliterated  hypogastric  artery.  The  depth 
of  these  fossae  depends  upon  the  tension  of  this  cord ;  so  that,  while 
sometimes  they  are  scarcely  visible,  at  others  they  are  deep  and 
well-marked.  They  are  of  importance,  since  they  correspond  with 
the  internal  and  external  abdominal  rings ;  hence,  the  greater 
depth  of  one  or  other  hollow  may  determine  the  locality  of  the  pro- 
trusion of  a  hernia.  Occasionally  the  deep  epigastric  artery  lies 
nearer  the  middle  line  than  it  normally  does,  so  that  we  may 
have  three  pouches  instead  of  two,  through  either  of  which  a 
hernia  may  emerge. 

The  abdominal  cavity  is  seen  to  be  composed  of  two  divisions — 
an  upper  or  abdomen  proper,  and  a  lower  or  the  pelvis.  It  is  the 
upper  division  that  we  are  about  to  describe. 

Take  now  a  survey  of  the  viscera  before  they  are  disturbed  from 
their  relative  positions. 

WHAT  is  SEEN  IR  tne  right  hypochondrium,  the  right  lobe  of 

ON  OPENING  THE  the  liver  is  seen  projecting  more  or  less  below  the 
ABDOMEN.  cartilages  of  the  ribs,  and  the  fundus  of  the  gall- 

bladder below  the  edge  of  the  liver,  near  the  end  of  the  ninth  costal 
cartilage.  In  the  left  hypochondrium  is  seen  more  or  less  of  the 
stomach  according  to  its  distension.  Across  the  umbilical  region 
extends  a  broad  fold  of  the  peritoneum  containing  fat,  the  great 
omentum,  which  descends  from  the  lower  curvature  of  the  stomach, 
forming  a  curtain  over  the  convolutions  of  the  small  intestine.  The 
breadth  of  this  fold  varies  ;  sometimes  being  so  shrunk  and  crumpled 
as  to  be  scarcely  visible.  The  lower  part  of  the  abdomen  and  part 
of  the  pelvis  are  occupied  by  the  small  intestine.  The  urinary 
bladder  is  not  apparent,  unless  distended  sufficiently  to  rise  out  of 
the  pelvis.  In  the  right  iliac  fossa  is  the  caput  coli,  the  com- 
mencement of  the  large  intestine  ;  but  the  ascending  part  of  the 
large  intestine  in  the  right  lumbar  region,  and  the  descending 


POSITION   OF   THE   ABDOMINAL   VISCERA.  449 

part  of  it  in  the  left,  are  not  visible  unless  distended  :  they  lie 
contracted  at  the  back  of  the  abdomen.  Such  are  the  viscera 
usually  seen  on  opening  the  abdomen ;  but  a  certain  latitude  is  to 
be  allowed,  as  sometimes  more  of  one  organ  is  seen  and  less  of 
another,  according  as  this  or  that  is  distended  or  hypertrophied. 
Much  also  depends  upon  the  amount  of  pressure  which  the  ribs 
have  undergone  during  life. 

'  PARTICULAR  The  position  of  each  viscus  should  now  be  ex- 

POSITION  OF  aniined  separately,  and  first  that  of  the  stomach. 

EACH  Viscus.  rj-^g  stomach  is  irregularly  conical  in  shape.     It 

THE  STOMACH.  is  placed  obliquely,  the  smaller  or  pyloric  end 
being  the  lower ;  its  great  end  is  situated  in  the  left  hypochon- 
drium  ;  its  narrow  or  pyloric  end  extends  obliquely  across  the 
epigastrium  into  the  right  hypochondrium3  where  it  is  overlapped 
by  the  liver. 

The  left  or  cardiac  end  is  situated  behind  the  ribs,  and  in  con- 
tact with  the  concavity  of  the  spleen,  to  which  it  is  connected  by 
&  fold  of  peritoneum.  In  front  it  has  the  abdominal  wall,  above 
it  has  the  liver  and  the  diaphragm,  and  below  it,  is  the  transverse 
colon;  the  right  or  pyloric  end  extends  to  the  gall-bladder,  and 
is  in  contact  with  the  under  aspect  of  the  liver,  where  it  is  con- 
tinuous with  the  duodenum ;  posteriorly,  it  rests  on  the  pancreas, 
the  aorta,  and  the  two  crura  of  the  diaphragm.  The  stomach  is 
connected  with  other  viscera  by  the  following  peritoneal  folds : 
(1)  the  great  omentum,  attached  to  its  lower  convex  border,  forms 
a  curtain  of  fat,  more  or  less  thick,  in  front  of  the  transverse  colon 
and  small  intestines;  (2)  the  gastro-hepatic  or  lesser  omentum, 
which  connects  the  lesser  curve  of  the  stomach  with  the  trans- 
verse fissure  of  the  liver ;  and  (3)  the  gastro-splenic  omentum, 
which  connects  the  cardiac  end  of  the  stomach  with*  the  hilum 
of  the  spleen.  The  relative  position  and  size  of  the  stomach  vary 
according  to  the  amount  of  distension :  when  much  distended, 
the  anterior  surface,  owing  to  the  greater  mobility  of  the  great 
curve  and  the  pyloric  end  of  the  stomach,  is  turned  upwards, 
and  the  lower  border  forwards.1 

1  Lesshaft  states  that  the  position  of  the  stomach  is  vertical,  and  that  when 
distended  it  does  not  alter  its  position,  but  that  it  is  affected  equally  in  all  direc- 

G  G 


450  RELATIVE   POSITION   OF  THE   SMALL   INTESTINES. 

The  first  part  of  the  intestinal  canal  is  termed 
intestinum  duodenum,  because  it  is  about  the 
breadth  of  twelve  fingers.  Commencing  at  the  pyloric  end  of  the 
stomach,  the  duodenum  ascends  as  high  as  the  neck  of  the  gall- 
bladder ;  then  turning  downwards  it  passes  in  front  of  the  right 
kidney ;  lastly,  making  another  bend,  it  crosses  the  spine  obliquely 
towards  the  left  side  of  the  second  lumbar  vertebra.  Here  the 
intestinum  jejunum  begins,  and  this  part  of  the  canal  may  be  see'n 
by  raising  the  transverse  colon.  Thus  the  duodenum  describes  a 
kind  of  horse-shoe  curve,  of  which  the  concavity  is  towards  the 
left,  and  embraces  the  large  end  or  head  of  the  pancreas.  For 
convenience  of  description  the  duodenum  is  divided  into  an  ascend- 
ing, a  descending,  and  a  transverse  portion.  The  first  is  com- 
pletely surrounded  by  a  peritoneal  covering ;  the  second  and  third 
are  only  covered  by  peritoneum  in  front,  and  are  fixed  to  the  back 
of  the  abdomen.  The  relative  anatomy  of  the  duodenum  will  be 
more  fully  seen  hereafter  (p.  474). 

JEJUNUM  AND  Pursuing  its  course  from  the  left  side  of  the 

ILEUM.  second  lumbar  vertebra,  the  intestinal  canal  forms 

a  number  of  convolutions,  occupying  the  lower  regions  of  the 
abdomen,  and  which  are  loosely  connected  to  the  spine  by  a  broad 
peritoneal  fold  termed  the  mesentery.  Of  these  convolutions,  the 
upper  two-fifths  constitute  the  intestinum  jejunum;  the  lower 
three-fifths,  the  intestinum  ileum.  This  is  an  arbitrary  division. 
There  is  no  definite  limit :  the  character  of  the  bowel  gradually 
changes — that  is,  it  becomes  less  vascular,  has  fewer  folds  of  the 
lining  membrane,  and  its  coats  are  therefore  less  substantial  to  the 
feel. 

COMMENCEMENT  ^n  *ne  right  iliac  fossa,  the  small  intestine  opens 
OF  LAEGE  IN-  into  the  left  side  of  the  caecum,  which  is  easily 

TESTINE.  recognised  by  its  sacculated  appearance  ;  here  the 

large  intestine  begins,  and  it  is  guarded  by  the  ileo-caacal  valve 
(fig.  103).  Immediately  below  the  junction  the  large  intestine  is 
expanded  into  a  blind  pouch,  about  two  and  a  half  inches  in  length 
and  breadth,  called  the  ccecum  or  caput  coli.  Into  the  back  part  of 

tions.  (Lancet,  March  11,  1882.)  This  opinion  is  not,  however,  generally  enter- 
tained by  anatomists. 


THE    LAEGE    INTESTINE. 


451 


this  pouch  opens  a  little  tube,  closed  at  the  other  end,  called  the 
appendix  vermiformis.  This  tube  varies  from  three  to  six  inches  in 
length,  is  about  as  thick  as  a  large  earthworm,  and  is  either  coiled 
up  behind  the  caecum,  or  connected  to  it  by  a  peritoneal  fold,  so  as 
to  hang  loose  in  the  abdomen.  It  is  hollow,  and  its  opening  into 
the  caecum  is  usually  guarded  by  a  valve  of  mucous  membrane. 

The  large  intestine  is  about  five  or  six  feet  in  length,  and  in 
its  course  it  describes  an  arch  which  encircles  the  convolutions  of 

FIG.  103. 


1.  Ileum. 

2.  Uaecum  or  caput  coli. 


3.  Appendix    vermi- 
formis. 


SECTION   THROUGH   THE   JUNCTION   OF   THE   LARGE   AND   SMALL  .INTESTINE   TO   SHOW 
THE   ILEO-C^CAL   VALVE   AND   APPENDIX   VERMIFOKMIS. 

the  small  intestines.  It  is  largest  at  its  commencement,  and  lessens 
in  size  until  at  the  upper  part  of  the  rectum  it  becomes  narrowest ; 
below  this  it  again  forms  a  dilatation,  the  ampulla,  just  above  its 
termination  at  the  anus.  It  is  successively  divided  into  caecum, 
ascending,  transverse,  and  descending  colon,  sigmoid  flexure  and 
rectum.  The  commencement  of  the  large  intestine  is  generally 
confined  by  the  peritoneum  to  the  iliac  fossa,  in  which  it^lies,  being- 
separated  from  the  iliacus  muscle  by  the  iliac  fascia  and  by  more  or 
less  connective  tissue  and  fat.1  Tracing  the  large  intestine  from 

1  But  this  is  not  invariably  so.     The  bowel  is,  in  some  subjects,  connected  to 

G  G  2 


452 


COUESE   OF   THE   LARGE   INTESTINE. 


this  point,  it  is  continued  as  the  ascending  colon.  We  find  it  some- 
what smaller  than  the  caecum,  and  it  ascends  through  the  right 
lumbar  region  in  front  of  the  right .  kidney  as  high  as  the  under 
surface  of  the  liver,  where  it  abruptly  makes  a  bend  to  the  left 
side — the  hepatic  flexure  of  the  colon :  it  then  crosses  the  umbilical 
region  transversely  from  right  to  left,  and  is  known  as  the  trans- 
verse colon.  Reaching  the  left  hypochondriac  region,  it  makes  a 
sharp  bend  downwards  beneath  the  lower  border  of  the  spleen, 
forming  the  splenic  flexure  of  the  colon ; l  thence  it  descends  in 
front  of  the  left  kidney,2  through  the  left  lumbar  region  into  the 
left  iliac,  as  the  descending  colon.  In  the  iliac  fossa  the  intestine, 

FIG.  104. 


RELATIVE    POSITION    OF    THE    KIDNEYS    AND    THE    LARGE    INTESTINE    SEEN 
FROM    BEHIND. 


L.  K.  Left  kidney. 

E.  K.  Eight  kidney,  crossed  obliquely  by  the 
last  dorsal  artery  and  nerve. 


A.  c.  Ascending  colon. 
D.  C.  Descending  colon. 


as  the  sigmoid  flexure,  becomes  narrow  and  makes  a  curve  like  the 
letter  S.  Lastly,  the  bowel  enters  the  pelvis  on  the  left  side  of  the 
sacrum,  and  here  takes  the  name  of  rectum.  This  term,  so  far  as 

the  fossa  by  a  fold  of  peritoneum  or  a  meso-ccecum.  I  have  seen  this  fold  suffi- 
ciently loose  to  allow  the  caput  coli  to  travel  over  to  the  left  iliac  fossa. 

1  This  transverse  part  of  the  colon,  in  some  instances,  makes  a  coil  behind  the 
stomach  to  the  diaphragm ;  such  a  state  of  things,  when  the  bowel  happens  to  be 
distended,  is  apt  to  give  rise  to  symptoms  of  diseased  heart.     See  some  observa- 
tions in  point  by  Dr.  Copland,  in  Lond.  Med.  Oaz.  1847,  vol.  v.  p.  660. 

2  The  contiguity  of  the  ascending  and  descending  colon  to  the  right  and  left 
kidney  respectively,  explains  the  occasional  bursting  of  renal  abscesses  into  the 
intestinal  canal. 


RELATIONS  OF  THE  LARGE  INTESTINE.  453 

concerns  the  human  subject,  is  misapplied ;  the  canal  runs  anything 
but  a  straight  course  through  the  pelvis,  since  it  curves  to  adapt 
itself  to  the  sacrum. 

Looking  at  the  entire  course  of  the  colon,  observe  that  it  forms 
an  arch,  of  which  the  concavity  embraces  the  convolutions  of  the 
small  intestines. 

Let  us  now  see  to  what  extent  the  small  and  the  large  intestines 
are  invested  with  a  peritoneal  coat.  The  small  intestines,  with  the 
exception  of  the  duodenum,  which  cannot  at  present  be  examined, 
we  shall  find  are  completely  surrounded  by  peritoneum,  except  at 
their  mesenteric  border  along  which  the  vessels  pass  to  the  bowel ; 
the  ccKCum  is  covered,  as  a  rule  only  in  front  and  on  its  sides,  the 
posterior  surface  being  connected  to  the  iliac  fascia  by  connective 
tissue ;  the  ascending  colon  is  also  only  covered  on  the  front  aspect 
and  sides,  the  posterior  surface  being  loosely  connected  by  areolar 
tissue  to  the  quadratus  lumborum  and  right  kidney ;  the  transverse 
colon  is  almost  entirely  surrounded  by  peritoneum,  which  is  re- 
flected horizontally  backwards  as  a  broad  double  layer — the  trans- 
verse meso-colon — to  the  spine  ;  the  descending  colon,  smaller  than 
the  transverse  colon,  and  more  deeply  situated  than  the  ascending 
colon,  is  only  invested  with  peritoneum  on  its  anterior  and  inner 
surfaces ;  the  sigmoid  flexure  is  completely  invested  with  peri- 
toneum, which  connects  this  part  of  the  bowels  with  a  loose  fold 
to  the  left  iliac  fossa ;  the  rectum  is  completely  surrounded  by 
peritoneum  in  its  upper  half,  and  is  connected  to  the  front  of  the 
sacrum  by  a  fold,  the  meso-vectum ;  the  lower  half  of  the  rectum, 
for  the  first  three  inches,  is  only  covered  in  front  with  peritoneum ; 
the  last  inch  and  a  half  has  no  peritoneal  investment  at  all.1 

EELATIONS  OF  At  present  we  have  only  traced  the  course  of 

THE  LAKGE  the  large  intestine  through  the  different  abdominal 

INTESTINE.  regions,  but  now  we  are  able  to  see  the  relations 

of  the  various  portions  of  the  bowel. 

The  ccecum  rests  in  the  right  iliac  fossa,  separated  from  the 

1  It  should  be  recollected,  that  the  ascending  and  descending  colon  are  not 
infrequently  completely  invested  by  peritoneum,  and  therefore,  virtually  speaking, 
have  a  mesentery.  This  occasional  occurrence  is  important  when  the  operation  of 
right  or  left  lumbar  colotomy  has  to  be  performed. 


454          RELATIONS  OF  THE  LARGE  INTESTINE. 

iliacus  by  the  iliac  fascia  and  connective  tissue  ;  in  front  it  has  the 
anterior  abdominal  wall. 

The  ascending  colon  has  behind  it,  the  quadratus  lumborum  and 
right  kidney ;  in  front,  it  has  the  abdominal  wall  and  small  in- 
testines ;  above,  it  is  in  contact  with  the  under  aspect  of  the  liver 
to  the  right  of  the  gall-bladder. 

The  transverse  colon  is  concave  posteriorly,  and  has  above,  the 
liver,  gall-bladder,  the  stomach,  and  the  lower  border  of  the  spleen ; 
behind,  it  has  the  transverse  meso-colon  and  the  third  part  of  the 
duodenum  ;  in  front,  it  is  in  contact  with  the  abdominal  wall  and 
great  omentum  ;  below,  with  the  small  intestines. 

The  descending  colon,  deeper  situated  than  the  ascending  colon, 
lies  behind,  in  contact  with  the  left  crus  of  the  diaphragm,  the  left 
kidney  and  quadratus  lumborum  ;  in  front,  with  the  small  intestines, 
and  on  its  left  side,  with  the  abdominal  wall. 

The  sigmoid  flexure  is  in  relation  behind  with  the  iliac  fossa,  the 
left  spermatic  artery  and  ureter,  the  left  common  iliac  vessels ;  in 
front,  with  the  small  intestines  and  abdominal  wall. 

The  relations  of  the  rectum  cannot  at  present  be  satisfactorily 
made  out ;  the  description  of  them  has  been  deferred  till  the 
dissection  of  the  side  view  of  the  pelvic  viscera. 

LENGTH  OF  THE         The  small  intestine,  including  the  duodenum, 
ALIMENTARY  varies  from  sixteen  to  twenty-four  feet  in  length, 

CANAL.  an(j  fae  large  intestine  from  five  feet  to  five  feet 

and  a  half;    these  measurements  are  subject  to  some  variation 
according  to  the  height  of  the  subject. 

The  average  lengths  of  the  different  portions  of  the  alimentary 
canal  are  as  follows  : — 

Duodenum         .  .  8  to  10  inches 

Jejunum   .         .  .  two-fifths     )  of  the  remaining  part 

Tleum        .         .  .  three-fifths  j      of  the  small  intestine 

Caecum      .         .  2^  inches 

Ascending  colon  .  8  inches 

Transverse  colon  .  12  inches 

Descending  colon  .  1 1  inches 

Sigmoid  flexure  .  22  inches 

Rectum  6  to  8  inches 


RELATIONS   OF  THE   LIVER.  455 

SITUATION  OF  The  liver  occupies  the  whole  of  the  right  hypo- 

•THE  LIVEB.  chondrium,  and  extends  over  the  epigastric  region, 

more  or  less,  into  the  left.  Unless  the  individual  be  very  corpulent 
we  can  ascertain  during  life  the  extent  to  which  the  liver  projects 
below  the  costal  cartilages,  and  the  general  dimensions  of  the  organ 
may  be  tolerably  well  told  by  percussion.  Its  anterior  border  is 
sharp  and  thin,  and  presents  in  the  epigastric  region  a  deep  notch 
for  the  round  ligament,  and  generally  projects  a  little  way  below 
the  ribs;  its  posterior  border  is  broad  and  connected  to  the 
diaphragm  by  the  coronary  ligament ;  it  is  in  relation  behind  with 
the  inferior  vena  cava,  the  aorta,  and  the  crura  of  the  diaphragm.  Its 
upper  convex  surface  ascends  as  high  as  the  fifth  intercostal  space,  is 
accurately  adapted  to  the  arch  of  the  diaphragm,  and  is  divided 
into  two  unequal  parts  by  the  falciform  or  suspensory  ligament ; 
its  under  surface  overlies  part  of  the  stomach,  and  of  the  duodenum, 
the  right  kidney  and  supra-renal  capsule,  and  the  hepatic  flexure 
of  the  colon.  Its  right  border  is  thick ;  its  left  is  thin  and  sharp. 
To  the  diaphragm  the  liver  is  connected  by  folds  of  peritoneum, 
called  ligaments.  One  of  these,  nearly  vertical  in  direction,  and 
called  the  suspensory,  or,  from  its  shape,  the  falciform,  ligament,  is 
situated  a  little  to  the  right  of  the  mesial  line.  The  lower  and 
free  edge  of  it  contains  the  impervious  remains  of  the  umbilical 
vein,  called  the  round  ligament.  The  suspensory  ligament,  traced 
backwards,  leads  to  another  broad  fold  extending  horizontally  from 
the  diaphragm  to  the  posterior  border  of  the  liver  ;  this  constitutes 
the  lateral  ligament,  right  or  left,  according  as  we  trace  it  on  one 
or  the  other  side  of  the  falciform  ligament. 

The  junction  of  the  lateral  and  falciform  ligaments  is  described 
by  some  authors  as  the  coronary  ligament. 

SITUATION  OF  The  gall-bladder  is  the  reservoir  for  the  bile, 

THE  GALL-  and  is  closely  confined  by  the  peritoneum  in  a 

BLADDEB.  slight  depression  on  the  under  surface  of  the  right 

lobe  of  the  liver,  to  which  it  is  connected  by  areolar  tissue  ;  occa- 
sionally the  gall-bladder  is  completely  surrounded  by  peritoneum. 
It  is  pyriform  in  shape,  and  its  broad  end  or  fundus,  covered  with 
peritoneum,  projects  beneath  the  anterior  border  of  the  liver  opposite 
the  ninth  costal  cartilage.  It  measures  three  to  four  inches  in 


456  RELATIONS   OF   THE   SPLEEN. 

length,  is  an  inch  and  a  half  broad,  and  contains  from  eight  to 
twelve  drachms.  The  neck  is  inclined  upwards  and  towards  the 
left,  and  is  firmly  connected  to  the  liver  by  areolar  tissue.  The 
gall-bladder  is  in  relation  above  with  the  liver  and  small  blood- 
vessels ;  below,  with  the  transverse  colon  and  with  the  first  portion 
of  the  duodenum ;  its  neck-  is  curved  upon  itself  like  the  letter  S, 
and  bending  downwards  terminates  in  the  cystic  duct.  It  some- 
times happens  that  the  gall-bladder,  in  consequence  of  some 
obstruction  to  its  duct,  becomes  unusually  distended,  and  occasions 
a  swelling  below  the  margin  of  the  ribs,  which  might  be  mistaken 
for  an  hepatic  abscess.1  The  close  proximity  of  the  gall-bladder  to 
the  duodenum  and  the  transverse  colon  explains  the  occasional 
evacuation  of  gall-stones  by  ulceration  into  the  intestinal  canal.2 

SITUATION  OF  The  spleen  is  the  dark,  purple-grey,  flattened 

THE  SPLEEN.  organ  deeply  situated  in  the  left  hypochondrium, 

between  the  stomach  and  the  ninth,  tenth,  and  eleventh  ribs.  It 
is  placed  nearly  vertically  ;  its  outer  surface  is  smooth  and  convex, 
to  correspond  with  the  diaphragm  and  ribs  ;  its  inner  surface,  where 
its  great  vessels  enter,  is  concave,  and  connected  to  the  great  end 
of  the  stomach  by  a  broad  peritoneal  fold,  called  the  gastro-splenic 
omentum.  Its  external  surface  is  in  relation  with  the  diaphragm 
which  separates  the  organ  from  the  ninth,  tenth,  and  eleventh  ribs ; 
its  internal  surface  is  concave,  and  presents  a  vertical  fissure — the 
hilum — situated  nearer  the  posterior  than  the  anterior  border  ;  it 
is  at  this  fissure  that  the  two  layers  of  peritoneum  are  reflected 
from  the  stomach  to  the  spleen,  and  the  splenic  vessels  enter  and 
emerge ;  it  is  in  relation  with  the  cardiac  end  of  the  stomach,  the 
tail  of  the  pancreas,  the  left  supra-renal  capsule,  and  the  left  crus 
of  the  diaphragm  ;  the  upper  border  is  rounded,  and  is  connected 
to  the  diaphragm  by  a  fold  of  peritoneum — the  suspensory  ligament ; 
the  lower  border  is  in  contact  with  the  splenic  flexure  of  the  colon ; 
the  posterior  border  is  thick,  and  is  connected  with  the  left  kidney 
by  areolar  tissue  ;  the  anterior  margin  usually  presents  a  more  or 
less  deep  notch.  Its  hilum  is  connected  with  the  cardiac  end  of 

1  See  cases  in  point  recorded  by  Andral,  Chir.  Med.  torn.  iv. ;  and  Graves, 
Dublin  Hospital  Reports,  vol.  iv. 

2  See  preparations  in  St.  Bartholomew's  Hospital  Museum. 


EELATIONS   OF   THE   KIDNEYS.  457 

the  stomach  by  a  fold  of  peritoneum — the  g astro-splenic  omentum ; 
and  with  the  under  surface  of  the  diaphragm  by  a  small  peritoneal 
fold — the  suspensory  ligament.1 

SITUATION  OF  This  is  the  large  salivary  gland  of  the  abdomen. 

THE  PANCKEAS.  It  is  placed  transversely  across  the  back  of  the 
abdomen,  in  front  of  the  spine,  about  the  level  of  the  first  lumbar 
vertebra.  It  is  about  seven  inches  in  length,  and  an  inch  and  a 
half  in  breadth.  Its  right  end  or  head  is  contained  within  the 
curve  of  the  duodenum  ;  its  left  end,  or  tail,  extends  as  far  as  the 
spleen.  The  further  connections  and  relations  of  the  pancreas 
cannot  at  this  stage  of  the  dissection  be  satisfactorily  seen. 

SITUATION  OF  The  kidneys  are  two  large  excretory  glands, 

THE  KIDNEYS.  situated  at  the  back  of  the  abdomen  in  each  lum- 

bar region,  nearly  opposite  the  two  last  dorsal  and  the  two  upper 
lumbar  vertebrae — the  right,  owing  to  the  size  of  the  liver,  being  a 
little  lower  than  the  left.  They  lie  imbedded  in  fat,  which  main- 
tains them  in  their  proper  position.  Behind,  they  rest  on  the  crus 
of  the  diaphragm,  on  the  quadratus  lumborum  and  psoas,  separated 
by  the  aponeurosis  of  the  transversalis ;  in  front,  the  right  kidney 
is  in  relation  with  the  peritoneum,  the  right  lobe  of  the  liver,  the 
second  part  of  the  duodenum,  and  the  ascending  colon  :  the  left 
kidney  is  in  contact  with  the  peritoneum,  the  cardiac  end  of  the 
stomach,  the  spleen,  the  end  of  the  pancreas,  and  the  descending 
colon  ;  externally,  it  is  convex,  and  in  contact  with  the  abdominal 
parietes ;  internally,  it  is  concave,  and  presents  a  deep  hollow — the 
hilum,  from  which  pass  the  ureter  and  large  vessels ;  above,  it  is  in 
relation  with  the  supra-renal  capsule  ;  below,  it  extends  nearly  as 
low  as  the  crest  of  the  ilium. 

SITUATION  OF  These  are  two  ductless  glands,  situated  at  the 

THE  SUPRA-RENAL  top  of  the  kidneys  and  behind  the  peritoneum. 
CAPSULES.  Tne  right  one  is  triangular;  the  left,  oval  and 

almond-shaped.  The  right  supra-renal  capsule  is  in  relation  in  front, 
with  the  under  aspect  of  the  liver ;  the  left,  with  the  pancreas  and 
spleen ;  behind,  it  rests  on  the  crus  of  the  diaphragm ;  the  upper 
border  is  convex  and  thin ;  the  lower  border  is  concave,  and  rests 

1  We  find  occasionally  in  the  gastro-splenic  omentum  one  or  more  small  spleens, 
in  addition  to  the  large  one. 


458  THE   PERITONEUM. 

on  the  kidney ;  the  inner  border  is  in  relation  with  the  semilunar 
ganglion  and  splanchnic  nerves,  and  with  the  vena  cava  on  the 
right  side,  and  with  the  aorta  on  the  left  side.  The  anterior  surface 
is  slightly  indented,  from  which  the  supra-renal  vein  passes  out  to 
join  on  the  right  side  the  inferior  vena  cava,  and  on  the  left  side 
the  left  renal  vein. 

A  certain  range  of  motion  being  necessary  to 
PERITONEUM.  ,         ,  ,       .      ,  ,  .,    ,       .  , 

the  abdominal  viscera,  they  are  provided  with  a 

serous  membrane,  called  the  peritoneum.  This  membrane,  like 
other  serous  membranes,  is  a  closed  sac,  one  part  of  which  lines  the 
containing  cavity,  the  other  is  reflected  over  the  contained  viscera. 
These  are  respectively  termed  the  parietal  and  the  visceral  layers. 
In  the  female,  however,  it  is  not,  strictly  speaking,  a  closed  sac, 
since  it  communicates  with  the  cavity  of  the  uterus  through  the 
Fallopian  tubes.  The  internal  surface  of  the  peritoneum  is  smooth 
and  polished,  and  lined  by  squarnous  endpthelium ;  the  external 
surface — the  sub-peritoneal  tissue — is  composed  of  areolar  tissue, 
which  connects  the  internal  layer  to  the  invested  viscus  or  abdo- 
minal parietes.  There  is  nothing  between  the  .parietal  and  the 
visceral  layers — in  other  words,  inside  the  sac — but  just  sufficient 
moisture  to  lubricate  its  smooth  and  polished  surface.  The  viscera 
are  all,  more  or  less,  outside  the  sac ;  some  lie  altogether  behind  it, 
as  the  pancreas,  kidneys,  and  supra-renal  capsules  ;  others,  as  the 
lower  parts  of  the  duodenum,  caecum,  ascending  and  descending 
colon,  are  only  partially  covered  by  it ;  while  others,  as  the  stomach, 
liver,  jejunum,  ileum,  and  some  parts  of  the  large  intestine,  are 
completely  invested  by  it :  these  latter  push  the  visceral  layer 
before  them,  and  so  give  rise  to  membranous  folds ;  the  larger  the 
fold,  the  freer  is  the  mobility  of  the  viscus  which  occasions  it. 

COURSE  OF  THE          Now   trace   the   peritoneum    as   a   continuous 
PERITONEUM.  membrane.     Since  the  peritoneum  is  a  perfect  sac, 

it  matters  not  where  we  begin  :  we  must  come  back  to  the  starting- 
point. 

If  a  longitudinal  section  be  made  through  the  viscera  in  the 
middle  of  the  body,  one  can  trace  the  peritoneum  thus — beginning 
at  the  diaphragm,  and  taking,  for  brevity's  sake,  two  layers  at  a 
time  (fig.  105). 


THE   PERITONEUM. 


459 


FIG.  105. 


From  the  diaphragm  two  layers  of  peritoneum  proceed  to  the 
liver,  forming  its  lateral  ligaments ;  they  separate  to  enclose  the 
liver,  meet  again  on  its  under  aspect,  and  pass  on,  under  the  name 
of  the  gastro-liepcutic  omentum,  to 
the  small  curve  of  the  stomach. 
Separating  here,  they  embrace 
the  stomach,  and,  meeting  again 
at  its  greater  curve,  pass  down 
like  a  curtain  over  the  small  in- 
testine to  form  the  great  omentum. 
At  the  lower  margin  of  the  great 
omentum,  they  are  reflected  up- 
wards (so  that  the  great  omentum 
consists  of  four  layers)  to  the  front 
of  the  transverse  colon,  which 
they  enclose,  and,  after  joining 
again  at  the  back  of  the  colon, 
proceed  to  the  spine,  forming  the 
transverse  meso-colon.  At  this 
situation  the  two  layers  diverge, 
the  upper  one  ascends  in  front  of 
the  pancreas,  and  the  crura  of  the 
diaphragm  to  its  under  surface, 
at  which  point  we  started.1 

The  peritoneum  passes  from 
the  under  surface  of  the  right  lobe 
of  the  liver  to  the  kidney,  forming 
a  slight  fold — the  hepato-renal 
fold ;  on  the  left  side,  where  the 
peritoneum  extends  from  the  dia- 
phragm to  the  cardiac  end  of  the  stomach,  it  passes  as  a  slight 
duplicature,  forming  the  gastro-phrenic  ligament ;  an  extension  of 

1  In  foetal  life,  the  ascending  layers  of  the  great  omentum  may  be  traced  back 
to  the  spine  near  the  pancreas  ;  and  here  the  layers  diverge  from  each  other.  The 
upper  layer  ascends  in  front  of  the  pancreas  to  the  diaphragm ;  the  lower  layer 
proceeds  over  the  arch  of  the  colon,  and  then  back  to  the  spine,  thus  forming  the 
transverse  meso-colon.  Its  reflections  afterwards  are  the  same  as  in  the  adult. 
As  the  foetus  grows,  the  great  omentum  becomes  adherent  to  the  arch  of  the  colon. 


DIAGRAM   OF   THE   PERITONEUM. 


460  THE    PERITONEUM. 

this  is  seen,  passing  as  a  distinct  fold — the  costo-colic  ligament — 
from  the  diaphragm  to  the  splenic  flexure  of  the  colon. 

The  lower  layer  is  reflected  from  the  spine  over  the  small  intes- 
tine, back  again  to  the  spine,  to  form  the  mesentery.  From  the 
root  of  the  mesentery  it  descends  into  the  pelvis,  and  invests  the 
upper  two-thirds  of  the  rectum.  From  the  rectum,  in  the  male,  it 
is  reflected  to  the  posterior  part  of  the  bladder,  forming  the  recto- 
vesical  pouch,  and  thence  to  the  wall  of  the  abdomen,  along  which 
it  can  be  traced  up  to  the  diaphragm.  In  the  female,  it  is  reflected 
from  the  rectum  on  to  the  posterior  wall  of  the  vagina  half  an  inch 
from  the  uterine  extremity,  constituting  the  recto-vaginal  pouch 
(Douglas*  poucli),  and  thence  over  all  the  back,  but  only  about  half- 
way down  the  front  of  the  uterus,  to  the  posterior  wall  of  the 
bladder ;  after  which  its  reflections  are  the  same  as  in  the  male.1 

Such  is  the  course  of  the  peritoneum  as  seen  in  a  longitudinal 
section,  but  there  are  lateral  reflections  which  cannot  be  seen  except 
in  a  transverse  section :  thus,  from  the  great  end  of  the  stomach, 
two  layers  proceed  to  the  spleen,  forming  the  g astro-splenic  amen- 
tum ;  from  the  transverse  meso-colon  it  is  reflected  on  either  side 
over  the  ascending  and  descending  colon. 

The  structures  completely  invested  with  peritoneum  are,  the 
stomach,  liver,  first  part  of  the  duodenum,  the  jejunum  and  ileum, 
the  transverse  colon,  sigmoid  flexure,  upper  part  of  rectum,  spleen, 
uterus,  and  ovaries. 

The  following  parts  of  the  alimentary  canal  are  only  partially 
covered  by  peritoneum  :  namely,  the  descending  and  transverse 
portions  of  the  duodenum,  the  caecum,  the  ascending  and  descend- 
ing colon  (with  exceptional  cases),  the  middle  part  of  the  rectum, 
the  upper  part  of  the  vagina,  and  the  hinder  wall  of  the  bladder. 

The  viscera  uncovered  by  peritoneum  are,  the  lower  part  of  the 
rectum,  the  anterior  and  the  lower  part  of  the  posterior  wall  of  the 
vagina,  the  anterior  and  part  of  the  posterior  wall  of  the  bladder. 

Anatomists  speak  of  the  lesser  cavity  of  the  peritoneum,  as  dis- 
tinguished from  the  greater.  This  lesser  cavity,  or  cavity  of  the 

1  For  a  detailed  description  of  the  development  of  the  great  omentum  and  the 
transverse  meso-colgn,  see  a  paper  by  C.  B.  Lockwood,  Journal  of  Anatomy  aiid 
Physiology,  vol.  xviii. 


LESSER  CAVITY  OF  THE  PERITONEUM. 


461 


great  omentum,  is  situated  behind  the  stomach  'and  the  descending 
layers  of  the  great  omentum.  If  air  be  blown  through  the  foramen 
of  Winslow  (which  is  the  constricted  communication  between  the 


FIG.  106. 


•G.P.  Greater  cavity  of 
the  peritoneum. 

L.P.  Lesser  cavity  of 
the  peritoneum. 

A.  Aorta. 


St.  Stomach. 

s.  Spleen. 

v.  Inferior  vena  cava. 

L.  Liver. 


DIAGRAM    OF   A    TRANSVERSE    SECTION    THROUGH    THE    UPPER    PART    OF    THE 
ABDOMINAL   CAVITY    SEEN    FROM    ABOVE. 

greater  and  lesser  cavities  of  the  peritoneum),  the  lesser  cavity  be- 
comes distended.  It  is  bounded  in  front  by  the  lesser  omentum, 
the  stomach,  and  the  descending  layers  of  the  great  omentum; 

FIG.  107. 


G.O.  The  great  omen- 
tum, with  its  ca. 
vity. 

j.  Small  intestine. 

A.  Aorta. 


v.  Inferior  vena  cava. 
A.C.  Ascending  colon. 
B.C.  Descending  colon. 
K.  Kidneys. 


DIAGRAM   OF   A   TRANSVERSE   SECTION   THROUGH   THE   LOWER   PART   OF   THE 
ABDOMINAL   CAVITY. 

behind,  by  the  ascending  layers  of  the  great  omentum,  the  colon, 
the  upper  layer  of  the  transverse  meso-colon  and  its  ascending 
layer;  above,  by  the  liver;  below,  by  the  turn  of  the  great 
omentum. 


462  THE   MESENTERY. 

FORAMEN  OF  This  foramen  is  the  narrow  circular  opening 

WINSLOW.  between   the  greater  and   lesser  cavities  of  the 

peritoneum,  through  which  the  two  cavities  communicate.  It  is 
situated  behind  the  right  edge  of  the  gastro-hepatic  or  lesser 
omentum.  By  passing  your  finger  into  it,  you  will  find  the 
foramen  bounded  above,  by  the  lobulus  Spigelii  or  caudatus  of  the 
liver ;  below,  by  the  commencement  of  the  duodenum  and  by  the 
curving  forwards  of  the  hepatic  artery ;  in  front,  by  the  lesser 
omentum,  enclosing  the  hepatic  artery  and  duct  and  the  vena 
portse ;  and  behind,  by  the  vena  cava  inferior. 

The  several  folds,  formed  by  the  reflections  of  the  peritoneum, 
which  connect  the  viscera  either  to  each  other  or  to  the  back  of  the 
abdomen,  are  classified  respectively  as  ligaments,  mesenteries,  and 
omenta :  the  ligaments  are  attached  to  the  viscera,  and  help  to 
maintain  them  in  position ;  the  mesenteries  pass  from  the  abdominal 
walls  to  the  large  and  small  intestines,  and  maintain  them  in  posi- 
tion and  allow  of  blood-vessels  to  pass  to  and  from  them ;  and  the 
omenta  are  broad,  flat  duplicatures  which  pass  from  the  stomach  to* 
the  neighbouring  viscera. 

This  is  the  fold  which  suspends  the  small  in- 
testine from  the  back  of  the  abdomen.  •  To  see  it, 
raise  the  great  omentum  and  the  transverse  arch  of  the  colon.  Its 
attached  part  or  root  is  about  six  inches  in  length,  and  extends 
from  the  left  side  of  the  second  lumbar  vertebra  obliquely  across 
the  spine  to  the  right  sacro-iliac  symphysis.  The  loose  part  of  the 
mesentery  is  very  broad,  and  curves  like  a  ruffle,  enclosing  the 
small  intestine  from  the  beginning  of  the  jejunum  to  the  end  of  the 
ileum.  Its  shape  resembles  an  open  fan,  and  its  length  from  the 
vertebral  column  to  its  attachment  to  the  intestine  is  about  four 
inches.  Above,  it  is  connected  with  the  under  surface  of  the  trans- 
verse meso-colon ;  below,  with  that  part  of  the  peritoneum  which 
lines  the  inner  part  of  the  caecum  and  ascending  colon.  We  must 
trace  between  its  two  layers  the  mesenteric  vessels,  nerves,  glands, 
and  lymphatics. 

TRANSVERSE  This  broad  fold  connects  the  transverse  colon 

MESO-COLON.  to   the  back  of  the    abdomen,  and   between   its 

layers  the   vessels   pass  to  and   from   this  portion  of  the  larger 


GREAT    OMENTUM.  463 

gut.  It  forms  an  imperfect  partition  dividing  the  abdomen 
into  an  upper  compartment,  containing  the  stomach,  liver,  and 
spleen;  and  a  lower,  containing  the  convolutions  of  the  small 
intestines. 

ASCENDING  AND  As  regards  the  caecum,  and  the  ascending  and 
DESCENDING  descending  portions  of  the  colon,  they  are,  as  a 

MESO-COLON.  general  rule,  bound  down  by  the  peritoneum  in 

their  respective  situations  (fig.  107).  The  peritoneum  covers  only 
two-thirds  or  thereabouts  of  their  anterior  surface ;  their  posterior 
surface  is  connected  by  loose  cellular  tissue  to  the  back  of  the 
abdomen.  The  colon,  ascending  or  descending,  can  therefore  be 
opened  in  the  lumbar  region,  below  the  kidney,  without  injury  to 
the  peritoneum :  a  fact  upon  which  is  founded  the  operation  of 
colotomy  for  the  relief  of  stricture  of  the  rectum.  In  some  cases, 
the  ascending  and  descending  colon  (more  commonly  the  latter) 
are  completely  surrounded  by  peritoneum  and  connected  to  the 
lumbar  regions,  respectively,  by  a  right  and  a  left  lumbar  meso- 
colon. 

SIGMOID  MESO-  The  sigmoid  flexure  is,  as  a  rule,  completely  in- 

COLON.  vested  by  peritoneum,  which  passes  as  a  thin  fold 

to  the  iliac  fossa,  allowing  a  considerable  amount  of  movement  of 
this  part  of  the  intestine. 

The  upper  third  of  the  rectum  is  also  surrounded 
MESO-EECTUM.        ,  .,  ,  .  ,  ,, 

by  peritoneum,  which  passes  to  the  sacrum  and 

thus  retains  it  in  position.  The  haemorrhoidal  vessels  pass  between 
its  layers. 

This  broad  peritoneal  fold,  known  also  as  the 
GREAT  OMENTUM.  7 .  .  -.      ,,  „         , 

gastro-coiic  omentum,  is  composed  ot  tour  layers, 

and  proceeds  as  a  double  layer  from  the  lower  border  of  the 
stomach,  as  far  as  the  pelvis,  where  these  two  layers  ascend  to 
enclose  the  transverse  colon.  It  lies  like  a  curtain  over  the  con- 
volutions of  the  small  intestines,  and  we  find  it  in  some  bodies 
extending  low  into  the  pelvis ;  in  others,  small  and  crumpled  up 
usually  in  the  left  hypochondrium.  Its  thickness  varies  consider- 
ably :  in  thin  subjects  it  is  often  translucent ;  in  corpulent  persons, 
on  the  other  hand,  it  is  loaded  with  fat,  and  contributes  in  great 
measure  to  the  size  of  the  abdomen. 


464          BRANCHES  OF  THE  ABDOMINAL  AORTA. 

GASTKO-HEPATIC  This  double  fold  passes  from  the  transverse 
OK  LESSEE  OMEN-  fissure  on  the  under  surface  of  the  liver  to  the 
TUJI-  upper  curve  of  the  stomach.  It  is  composed  of 

two  layers,  and  between  them  are  the  portal  vein  and  hepatic  artery 
with  the  nerves  going  to  the  liver,  and  the  hepatic  duct  and 
lymphatics  coming  from  it.  The  right  border'  of  this  fold  is  free, 
and  forms  the  anterior  rounded  margin  of  a  constriction,  called 
the  foramen  of  Winslow,  which  leads  into  the  lesser  cavity  of  the 
peritoneum :  its  left  border  passes  on  to  the  oesophagus.  In  this 
fold  the  common  bile  duct  lies  to  the  right,  .the  -hepatic  artery 
to  the  left,  and  the  vena  portge  behind  and  between  them.  If 
now  the  finger  be  introduced  behind  the  right  border,  it  passes 
through  the  foramen  of  Winslow  into  the  lesser  cavity  of  the 
peritoneum. 

GASTKO-  This  fold  proceeds  from  the  great  end  of  the 

SPLENIC  OMEN-  stomach  to  the  spleen,  and  is  continuous  below 
TUM-  with  the  great  omentum.  It  contains  between  its 

layers  the  branches,  vasa  brevia,  which  proceed  from  the  splenic 
artery  to  the  great  end  of  the  stomach. 

The   reflections   of  the   peritoneum   from   the 
abdominal   walls   to    the   liver,   the   spleen,    the 
bladder,  and  uterus,  and  constituting  their  ligaments,  have  been,  or 
will  be,  described  with  the  respective  viscera. 

BRANCHES  OF  Our  next  object  should  be  the  examination  of 

THE  ABDOMINAL  the  arteries  which  supply  the  viscera.  The  abdo- 
AOBTA.  mined  aorta  enters  the  abdomen  between  the  pillars 

of  the  diaphragm  in  front  of  the  last  dorsal  vertebra,  and  then, 
descending  a  little  to  the  left  of  the  spine,  divides  on  the  body  of 
the  fourth  lumbar  vertebra,  a  little  to  the  left  of  the  middle  line, 
into  the  two  common  iliac  arteries.  The  relations  of  the  aorta 
cannot  at  present  be  sufficiently  made  out,  so  that  this  will  be 
described  later  on.  In  its  course  it  gives  off  its  branches  in  the 
following  order  (fig.  108)  : — 

1.  The  phrenic,  for  the  supply  of  the  diaphragm. 

2.  The  cosliac   axis,  a  short  thick  trunk,  which  immediately 
subdivides  into  three  branches  for  the  supply  of  the  stomach,  the 
liver,  and  the  spleen. 


BRANCHES   OF   THE   ABDOMINAL   AORTA.  465 

3.  The   superior   mesenteric,  for  the  supply  of  all  the  small 
intestines,  and  the  upper  half  of  the  large. 

4,  5.  The  supra-renal  and  the  renal  arteries. 

6.  The  spermatic,  for  the  testicles ;  the  ovarian,  for  the  ovaries. 

7.  The  inferior  mesenteric,  for  the  supply  of  the  lower  half  of 
the  large  intestine. 

8.  The  lumbar,  four  branches  analogous  to  the  intercostals,  for 
the  supply  of  the  back  part  of  the  abdomen. 

FIG.  108. 


-j  !»•       i*tii»»jtoj»Kfi — gg.Kiiiiu iniyimi  |i 

1.  Phrenic.  6.  Spermatic. 

2.  Cceliac  axis.  HHH—  7-  Inferi°r  mesenteric. 

3.  Superior  mesenteric.  °  **          tji5|  8'  Lumbar- 

4.  Supra-renal.  JRa  **•  Sacra  media. 

5.  Renal. 


BRANCHES  OF  THE  ABDOMINAL  AORTA. 


9.  The  arteria  sacra  media,  which  is  given  off  at  the  bifurcation 
of  the  aorta,  supplies  the  fifth  lumbar  artery  and,  running  down 
in  front  of  the  sacrum,  supplies  the  rectum  and  other  structures. 

By  some  anatomists  the  branches  are  arranged  in  two  classes 
— those  destined  to  supply  the  viscera,  and  those  to  supply  the 
abdominal  parietes :  the  former,  are  the  cceliac  axis,  supra-renal, 
renal,  spermatic,  superior  and  inferior  mesenteric  arteries;  the 
latter  are  the  phrenic,  the  lumbar,  and  sacra  media  arteries. 

H  H 


466  CCELIAC   AXIS. 

These  branches  are  to  be  traced  throughout  in 
the  following  order.  Take  the  coeliac  axis  first. 
To  dissect  this  artery  and  its  branches,  the  liver  must  be  well 
raised  and  the  stomach  drawn  down,  as  in  fig.  109,  and  the  anterior 
layer  of  peritoneum  removed  from  the  gastro-hepatic  omentum. 
A  close  network  of  very  tough  tissue  surrounds  the  visceral  branches 
of  the  aorta.  This  tissue  consists  almost  entirely  of  plexuses  of 
nerves,  derived  from  the  sympathetic  system,  each  plexus  taking 
the  name  of  the  artery  which  it  surrounds.  Of  these  plexuses,  the 
largest  surrounds  the  coeliac  axis  like  a  ring.  This  is  the  solar 
plexus,  and  is  formed  by  the  junction  of  the  two  semilunar  gan- 
glia (see  Dissection  of  Thorax,  p.  189).  From  this,  as  from  a  root, 
other  secondary  plexuses  branch  off,  and  surround  the  following 
arteries — the  phrenic,  coronary,  hepatic,  splenic,  superior  mesen- 
teric,  inferior  mesenteric,  and  renal;  the  plexuses  receiving  the 
names  of  the  arteries  around  which  they  twine.  It  requires  a  lean 
subject  and  much  patience  to  trace  them. 

CCELIAC  Axis  AND  The  coeliac  axis  arises  from  the  front  of  the 
ITS  BRANCHES.  aorta,  between  the  pillars  of  the  diaphragm,  im- 
mediately above  the  upper  border  of  the  pancreas,  to  the  left  of 
the  lobulus  Spigelii,  to  the  right  of  the  cardiac  end  of  the  stomach, 
and  having  the  semilunar  ganglia  on  each  side.  It  is  a  short, 
thick  trunk  which  runs  between  the  two  layers  of  the  lesser  omen- 
tum, and,  after  a  course  of  about  half  an  inch,  divides  into  three 
branches,  the  hepatic  running  to  the  right,  the  splenic  to  the  left, 
and  the  coronaria  ventriculi  upwards  and  to  the  left  side. 

The  following  is  the  plan  of  the  coeliac  axis  and  its  branches : — 

( Coronaria    ventri-  ( ossophageal. 
culi.  |  gastric. 

/pyloric.  (gastro-epiploicadextra. 

Hepatic    .        .     \  gastro-duodenalis.  -I  pancreatico-duodenalis 

( cystic.  I     superior. 

/pancreatic  branches. 
Splenic     .         .     \  gastro-epiploica  sinistra. 

\vasa  brevia  to  stomach. 

COBONAKIA  The   coronaria  ventriculi,  the   smallest  of  the 

VENTBICULI.  three,   ascends  a  little  to   the   left   towards   the 

oesophageal  end  of  the  stomach,  where  it  gives  off  oesophageal 


CCELIAC  Axis 


BRANCHES   OF   THE   CCELIAC   AXIS. 


467 


branches,  which  anastomose  with  the  cesophageal  branches  of  the 
thoracic  aorta ;  and  others  to  the  cardiac  end  of  the  stomach,  which 
inosculate  with  the  vasa  brevia  of  the  splenic  artery.  It  then  runs 
from  left  to  right,  along  the  lesser  curvature  of  the  stomach  towards 
the  pylorus,  supplying  branches  on  both  surfaces  of  the  stomach, 
and  finally  anastomoses  with  the  pyloric  branch  of  the  hepatic 
artery. 

FIG.  109. 


Gall- 
bladder. 


Kidney    . 

Descending 
duodenum 


Termination 
of  bile-duct . 


— 1--  Spleen. 


"  "Commencement  of  the  intesti- 
num  jejunum. 


DIAGRAM   OF   THE    BBANCHES   OF    THE    CCELIAC   AXIS. 
(Pancreas  in  dotted  outline  behind  the  stomach.) 


1.  Coronaria  ventriculi. 

2.  Splenic  a. 

3.  Hepatic  a. 

4.  Pyloric  a. 


5.  Gastro-duodenalis. 

6.  Gastro-epiploica  sinistra. 

7.  Vasa  brevia. 

8.  Superior  mesenteric  a. 


HEPATIC 
AETEBY. 


The  hepatic  artery  ascends  to  the  right  between 
the  layers  of  the  lesser  omentum  to  the  transverse 
fissure  of  the  liver,  where  it  divides  into  two  branches,  right  and 
left,  for  the  supply  of  the  respective  lobes  of  the  liver. 

In  its  course  to  the  liver,  it  lies  to  the  left  of  the  common  bile- 

H  H  2 


468  BRANCHES   OF   THE   CCELIAC   AXIS. 

duct,  and  in  front  of  the  portal  vein :  all  three  are  contained  in 
the  right  half  of  the  lesser  omentum.     The  hepatic  gives  off — 

a.  The  pyloric,  which  descends  to  the  upper  border  of  the  pylorus, 
and  runs  along  the  lesser  curve  of  the  stomach  from  right  to  left, 
inosculating  with  the  coronaria  ventriculi. 

b.  The  gastro-duodenalis  descends  behind  the  ascending  portion  of 
the  duodenum,  divides,  after  a  short  course,  into  (a)  the  gastro-epiploica 
dextra,  which  runs  along  the  greater  curve  of  the  stomach,  between  the 
layers  of  the  great  omentum,  from  right  to  left,  and  anastomoses  with 
the  gastro-epiploica  sinistra  from  the  splenic,  supplying  both  surfaces 
of  the  stomach  and  the  great  omentum  ;  and  (ft)  the  pancreatico-duode- 
nalis  superior,  which  runs  down  between  the  head  of  the  pancreas  and 
the  descending  portion  of  the  duodenum,  and  anastomoses  with  the 
pancreatico-duodenalis  inferior,  a  branch  of  the  superior  mesenteric, 
and  with  the  pancreatic  branches  of  the  splenic. 

c.  The  cystic,  commonly  a  branch  of  the  right  hepatic,  ascends  along 
the  neck  of  the  gall-bladder,  and  divides  into  two  branches,  one  of  which 
ramifies  on  the   under  surface  of  the  gall-bladder,  the  other  passes 
between  the  liver  and  the  upper  surface  of  the  gall-bladder. 

SPLENIC  The  splenic,  the  largest  of  the  three,  proceeds 

AETEEY.  tortuously  towards  the  left  side,  above  its  corre- 

sponding vein,  along  the  upper  border  of  the  pancreas  to  the  hilum 
of  the  spleen,  which  it  enters  by  numerous  branches. 

It  gives  off  :  1.  Several  small  branches  to  the  pancreas,  pancreaticce 
parvce  :  one,  rather  larger  than  the  rest,  pancreatica  magna,  accom- 
panies the  pancreatic  duct.  These  arteries  anastomose  with  the  pan- 
creatico-duodenal  branches  of  the  hepatic  and  superior  mesenteric 
arteries.  2.  The  gastro-epiploica  sinistra,  which  runs  to  the  right 
along  the  great  curve  of  the  stomach,  between  the  layers  of  the  great 
omentum,  and  inosculates  with  the  gastro-epiploica  dextra.  3.  Vasa 
brevia,  five  to  seven  in  number,  which  proceed  between  the  layers  of 
the  gastro-splenic  omentum,  to  the  great  end  of  the  stomach,  where  they 
communicate  with  branches  from  the  coronaria  ventriculi,  and  the 
gastro-epiploica  sinistra.  4.  The  splenic  branches  are  five  or  six  in 
number,  and  enter  the  fissure  of  the  spleen. 

Thus  the  stomach  is  supplied  with  blood  by  four  channels, 
which  by  their  inosculations  form  a  main  artery  along  its  lesser 


VENA   PORT^l.  469 

curve,  another  along  its  greater;  from  these,  numerous  branches 
are  furnished  to  both  surfaces  of  the  stomach.  The  artery  of  the 
greater  curve  also  sends  down  numerous  omental  branches,  which 
form  a  network  between  the  layers  of  the  great  omentum. 

The  vein  corresponding  to  the  coronaria  ventriculi  artery,  called 
the  coronary,  commences  close  to  the  pylorus,  runs  along  the  lesser 
curve  of  the  stomach  as  far  as  the  oesophagus,  and  then  descending 
to  the  right,  between  the  two  layers  of  the  gastro-hepatic  omentum 
opens  into  the  vena  portae.1 

The  splenic  vein  returns  the  blood  from  the  spleen  by  five  or 
six  branches  which  unite  to  form  a  single  trunk.  This  runs  along 
the  upper  border  of  the  pancreas  below  the  artery,  and  after  re- 
ceiving the  branches  corresponding  to  the  branches  of  the  artery 
and  the  inferior  mesenteric  vein,  joins  the  superior  mesenteric 
vein  to  form  the  vena  portas. 

The  hepatic  veins  do  not  run  with  the  hepatic  artery,  but 
return  the  blood  from  the  liver  and  terminate  in  the  vena  portse. 

VENAPOKT^::  The  veins  which    return   the   blood   from   the 

ITS  PECULIABITIES.  abdominal  portion  of  the  alimentary  canal,  the 
pancreas,  and  the  spleen,  do  not  empty  themselves  into  the  vena 
cava  inferior,  but  all  unite  into  one  large  vein,  called  the  vena 
2)ortce,  which  ramifies  throughout  the  liver,  and  secretes  the  bile. 
The  trunk  of  the  vena  portaa  itself  is  about  three  inches  long. 
Tracing  it  downwards,  you  find  that  it  is  formed  behind  the  great 
end  of  the  pancreas  and  in  front  of  the  inferior  cava,  by  the  con- 
fluence of  the  splenic  and  superior  mesenteric  veins  (fig.  110).  In 
its  passage  to  the  liver,  the  vena  portae  is  accompanied  by  the 
hepatic  artery  and  the  common  bile-duct,  lying  behind  and  between 
them.  At  the  transverse  fissure  of  the  liver  it  presents  a  slight 
enlargement,  called  the  sinus,  and  then  divides  into  two  branches 
corresponding  to  the  right  and  left  lobes.  The  vein  ramifies  in 
the  substance  of  the  liver  like  an  artery,  and  is  surrounded,  with 
the  branches  of  the  hepatic  artery  and  duct,  in  a  sheath  of  areolar 
hepatic  tissue  called  Glisson's  capsule.  The  vena  portae  may,  then, 
be  compared  to  the  stem  of  a  tree,  of  which  the  roots  arise  in  the 
digestive  organs,  and  the  branches  spread  out  in  the  liver.  After 

1  See  Walsham  in  the  Journal  of  Anatomy  -and  Physiology,  vol.  xiv.  p.  399. 


470 


COMMON   BILE   DUCT. 


Fm.  110. 


\ 


HEPATIC  DUCT. 


receiving  the  veins  corresponding  to  the  branches  of  the  hepatic 
artery,  the  vena  portas  returns  its  blood  into  the  inferior  vena  cava 
through  the  venee  cavse  hepaticse. 

The  veins  which  empty  themselves  into  the  vena  portae  have 
no   valves.     Therefore,  if  any  obstruction   arises   in   the  venous 

circulation  through  the  liver, 
the  roots  of  the  portal  vein 
are  apt  to  become  congested  : 
this  is  a  common  cause  of 
haemorrhoids,  diarrhoea,  hae- 
morrhage from  the  bowels, 
and  ascites. 

The     he- 
patic duct  is 

formed  by  the  junction  of  the 
right  and  left  hepatic  ducts, 
which  issue  from  the  trans- 
verse fissure.  The  hepatic 
duct  descends  nearly  verti- 
cally for  about  an  inch  and 
a  half,  when  it  is  joined  at 
an  acute  angle  by  the  cystic 
duct.  The 
cystic  duct, 

about  an  inch  in  length, 
descends,  from  the  neck  of 
the  gall  bladder,  towards  the 
left  in  the  gastro-hepatic 
omentum,  lying  to  the  right 
of  the  hepatic  artery  and  in 
front  of  the  vena  portae.  The 
hepatic  and  cystic  ducts  unite  to  form  the  ductu 
communis  cJioledochus,  or  the  common  bile  duct 
the  duct  thus  formed,  passes  downwards  and  to 
the  left,  between  the  two  layers  of  the  lesser  omentum,  close  to 
its  right  border.  It  is  about  three  inches  long,  and  if  distended 
would  be  about  the  size  of  a  crow-quill.  It  descends  behind  the 


CYSTIC  DUCT. 


DIAGRAM  OF  THE  VENA  PORTJE. 

(The  arrow  is  introduced  behind  the  free 
border  of  the  lesser  omentum.) 


DUCTUS  COM- 
MUNIS  CHOLE- 

DOCHUS. 


COMMON   BILE   DUCT. 


471 


first  portion  of  the  duodenum ;  in  front  of  the  vena  portge ;  to 
the  right  of  the  hepatic  artery ;  to  the  left  of  the  descending 
portion  of  the  duodenum  ;  and  behind  the  head  of  the  pancreas. 
Then  turning  towards  the  right,  it  gets  behind  the  descending 
duodenum,  and  opens  obliquely  into  the  back  part  of  the  second 
portion,  near  the  junction  with  the  third.  The  duct  runs  through 
the  coats  of  the  bowel  for  nearly  three-quarters  of  an  inch,  and 
sometimes  before  doing  so  unites  with  the  pancreatic  duct  (p.  470). 

FIG.  111. 


1.  Superior  mesenteric  a. 

2.  Colica  media. 

3.  Colica  dextra. 

4.  Beo-colica. 


5.  Inferior  mesenteric  a. 

6.  Colica  sinistra. 

7.  Arteria  sigmoidea. 

8.  Superior  haemorrhoidal 


PLAN   OF   THE    MESENTERIC   ARTERIES,   AND   THEIR   COMMUNICATIONS.1 


DISSECTION. 


The  great  omentum,  with  the  arch  of  the  colon, 
must  now  be  turned  up  over  the  chest,  and  the 
small  intestines  pushed  towards  the  left  side.  Then,  by  removing 
the  anterior  layer  of  the  peritoneum  from  the  mesentery,  we  expose 
the  mode  in  which  the  superior  mesenteric  artery  ramifies  so  as 
to  supply  the  small  intestines.  In  making  this  dissection,  the 
mesenteric  glands  immediately  attract  notice.  They  lie  in  great 
numbers  between  the  layers  of  the  mesentery,  and  vary  consider- 
ably in  size.  The  fine  tubes,  called  lacteal  vessels,  which  traverse 

1  The  inferior  pancreatico-duodenal  artery  is  not  represented. 


472  SUPERIOR  MESENTERIC  ARTERY. 

the  glands,  are  too  thin  and  transparent  to  be  seen  under  ordinary 
circumstances.  But  in  cases  where  sudden  death  has  taken  place 
during  digestion,  they  are  found  distended  with  chyle,  and  can  be 
traced  into  the  glands  from  all  parts  of  the  small  intestine.1  After 
traversing  the  glands,  they  all  eventually  empty  their  contents  into 
the  receptaculum  chyli  (p.  184). 

SUPERIOR  This  large  artery  arises  from  the  front  of  the 

MESENTEEIC  aorta  just  below  the  coeliac  axis,  descends  beneath 

ABTEBY  AND  the   pancreas,  in  front  of  the  transverse  part  of 

BRANCHES.  tlie  auoaemim  fa  4g7),  and  then  runs  between 

the  layers  of  the  mesentery  towards  the  right  iliac  fossa,  where 
it  terminates  in  branches  for  the  supply  of  the  caecum.  Thus  it 
describes  a  gentle  curve  from  left  to  right.  It  is  crossed  by  the 
pancreas  and  splenic  vein,  and  will  be  seen  to  supply  the  descend- 
ing and  transverse  duodenum,  the  jejunum,  ileum,  and  the  ascend- 
ing and  transverse  colon.  It  is  accompanied  by  its  corresponding 
vein,  and  is  surrounded  by  the  superior  mesenteric  sympathetic 
plexus.  It  gives  off  the  following  branches  : — 

1.  The  inferior  pancreatico-duodenal  branch,  which  runs  up  behind 
the  pancreas,  within  the  concavity  of  the  duodenum,  to  inosculate  with 
the  superior  pancreatico-duodenal  branch  of  the  hepatic. 

2.  Vasa  intestini  tenuis  of  the  small  intestine,  from  ten  to  sixteen 
in  number,  are  given  off  from  the  left  or  convex  side  of  the  curve,  and 
are  distributed  to  the  jejunum  and  ileum  ;  while  from  the  concave  side 
come — 

3.  The  ileo-colic ; 

4.  The  right  colic,  for  the  supply  of  the  ileum,  caecum,  and  ascend- 
ing colon ;  and 

5.  The  middle  colic,  for  the  supply  of  the  transverse  colon. 

The  student  should  now  trace  the  branches  to  the  small  intes- 
tine, in  order  to  see  the  series  of  arches  which  they  form  by  their 
mutual  inosculations.  There  are  three  or  four  tiers  of  them,  each 
tier  composed  of  smaller  and  more  numerous  branches  than  the 
preceding.  The  ultimate  branches  ramify  in  circles  round  the 
intestine.  This  circular  arrangement  of  the  vessels  in  the  coats 

1  The  arrangement  of  the  chyliferous  vessels  is  well  displayed  in  the  plates  of 
Mascagni. 


INFERIOR  MESENTERIC   ARTERY.  473 

of  the  bowel  is  practically  interesting,  because  it  enables  one  in 
almost  all  cases  to  distinguish  the  intestine  from  the  hernial  sac. 

The  colic  branches  of  the  superior  mesenteric  are  the  ileo-colict 
which  is  the  continuation  of  the  main  trunk,  and  divides  into  two 
branches  :  one  supplies  the  lower  part  of  the  ileum,  and  the  other  the 
csecum ; 

The  right  colic,  which  proceeds  towards  the  ascending  colon  ;  and 
The  middle  colic,  which  ascends  between  the  layers  of  the  meso- 
colon  to  the  arch.  They  are  arranged  after  the  same  plan  as  those  of 
the  small  intestine  :  that  is,  they  inosculate  and  form  a  series  of  arches 
which  successively  decrease  in  size,  and  finally  terminate  in  circles 
round  the  bowel. 

The  superior  mesenteric  vein  joins  the  splenic  behind  the 
pancreas,  and  forms  the  vena  portse  (p.  470). 

_,  To  trace  this  artery,  the  small  intestine  must  be 

DISSECTION  OF  , 

THE  INFERIOR  drawn  over  towards  the  right  side,  and  the  peri- 

MESENTEEIC  toneum  covering  the  artery  removed,  since   the 

ABTEEY  AND  artery  lies  behind  the  peritoneum.     It  is  given  off 

from  the  front  of  the  aorta,  about  two  inches 
above  its  bifurcation,  and  is  surrounded  by  the  inferior  mesenteric 
plexus  of  sympathetic  nerves.  Descending  towards  the  left  iliac 
fossa,  it  crosses  obliquely  over  the  left  common  iliac  artery,  passes 
between  the  layers  of  the  meso-rectum,  and,  taking  the  name  of 
superior  hcemorrhoidal,  is  finally  distributed  to  the  upper  part  of 
the  rectum.  Its  branches  are  : — 

1.  The  colica  sinistra,  which  crosses  behind  the  peritoneum,  over  the 
left  kidney,  and  supplies  the  descending  colon. 

2.  The  sigmoidea,  which  runs  over  the  psoas,  is  distributed  to  the 
sigmoid  flexure. 

3.  The  superior  hcemorrhoidal,  which  supplies  the  upper  part  of  the 
rectum,  and  will  be  dissected  with  the  side  view  of  the  pelvis. 

These  branches  of  the  inferior  mesenteric  inosculate  in  the  form 
of  arches,  like  the  colic  branches  of  the  superior  mesenteric.  The 
colica  sinistra,  too,  forms  a  large  arterial  arch  with  the  colica  media, 
so  that  there  is  a  chain  of  arterial  communications  from  one  end  to 
the  other  of  the  intestinal  canal  (fig.  111). 


474  RELATIONS   OF   THE   DUODENUM. 

The  inferior  mesenteric  vein  ascends  nearly  vertically  behind 
the  peritoneum,  passes  in  front  of  the  left  psoas,  behind  the  third 
portion  of  the  duodenum  and  the  pancreas,  and  joins  the  splenic 
behind  the  pancreas. 

To  see  the  relations  of  the  duodenum  and  the 
pancreas,  two  ligatures  about  an  inch  apart  should 
be  placed  on  the  upper  end  of  the  jejunum,  and  two  others  at  a 
similar  distance  apart  on  the  lower  end  of  the  sigmoid  flexure  of 
the  colon.  After  the  jejunum  and  the  sigmoid  flexure  have  been 
divided  between  the  ligatures  respectively,  the  small  and  large  in- 
testines are  to  be  removed  by  cutting  through  the  peritoneal  folds 
which  connect  them  to  the  abdominal  walls.  By  turning  up  the 
stomach,  we  expose  the  duodenum  curving  round  the  great  end  of 
the  pancreas. 

DUODENUM,  The   duodenum   (p.    467)    commences   at   the 

BELATIONS  OF.  pyloric  end  of  the  stomach,  and  terminates  on  the 

left  side  of  the  second  lumbar  vertebra,  where  the  intestinum 
jejunum  begins.  It  is  about  eight  to  ten  inches  in  length,  and  is 
divided  into  three  parts,  an  ascending,  descending,  and  transverse. 

The  first  portion  ascends  obliquely  as  high  as  the  neck  of  the 
gall-bladder  ;  then,  making  a  sudden  bend,  it  descends  in  front  of 
the  right  kidney  as  low  as  the  third  lumbar  vertebra.  Lastly, 
making  another  bend,  it  ascends  obliquely  across  the  spine  to  the 
left  side  of  the  second  lumbar  vertebra :  here  the  intestine  takes 
the  name  of  jejunum.  Thus  the  duodenum  describes  a  horseshoe 
curve,  the  concavity  of  which  is  directed  towards  the  left  side,  and 
embraces  the  head  of  the  pancreas. 

The  first  or  ascending  portion  is  about  two  inches  long,  and  is 
completely  invested  by  peritoneum.  It  is  comparatively  free,  so 
that  the  movements  of  the  stomach  may  not  be  restricted.  In 
front  of  it  are  the  liver  and  the  neck  of  the  gall-bladder.  Behind 
it  are  the  bile-duct,  the  hepatic  artery,  and  the  vena  portee.  The 
second  or  descending  portion  is  about  three  inches  long,  and  is 
covered  by  peritoneum  only  on  its  anterior  surface.  It  is  firmly 
connected  to  the  deeper  structures  behind,  and  to  the  pancreas  on 
its  left  side,  so  that  no  movement  is  permitted  in  this  portion. 
It  descends  from  the  neck  of  the  gall-bladder  to  the  right  side  of 


RELATIONS  OF  THE  PANCREAS.  475 

the  body  of  the  third  lumbar  vertebra.  It  lies  behind  the  trans- 
verse colon,  in  front  of  the  right  kidney  and  the  ductus  communis 
choledochus  ;  on  the  left  side  it  is  in  relation  with  the  head  of  the 
pancreas,  its  duct,  and  the  superior  and  inferior  pancreatico-duo- 
denal  arteries.  The  third  or  transverse  portion,  about  four  inches 
long,  is  situated  behind  the  transverse  meso-colon,  just  above  the 
mesentery  and  the  superior  mesenteric  vessels.  Above  it,  are  the 
pancreas,  and  the  superior  mesenteric  artery  and  vein  which  pass 
between  the  pancreas  and  the  duodenum  :  behind,  it  rests  upon 
the  crura  of  the  diaphragm,  the  inferior  vena  cava,  and  the  aorta. 
This  portion,  like  the  second,  is  only  covered  in  front  by  peri- 
toneum. Notice  how  firmly  the  duodenum  is  braced  up  on  the  left 
side  of  the  second  lumbar  vertebra ;  and  how  the  jejunum  begins 
here  by  an  abrupt  downward  bend. 

PANCREAS,  The   pancreas  is  a  large   compound  racemose 

BELATIONS  OF.  gland,  situated  immediately  behind  the  stomach 

(p.  470).  It  is  of  an  elongated  form,  and  of  pinkish-white  colour. 
It  is  placed  transversely  across  the  spine  ;  its  larger  end,  or  head, 
is  embraced  by  the  duodenum  ;  its  lesser  end,  or  tail,  is  in  contact 
with  the  spleen.  It  is  about  six  to  eight  inches  in  length,  its 
average  breadth  is  one  inch  and  a  half,  and  its  thickness  from  half 
an  inch  to  an  inch.  Its  weight  is  from  2£  oz.  to  3^  oz.,  although  it 
frequently  exceeds  the  latter  weight. 

In  front,  the  gland  has  the  ascending  layer  of  the  transverse 
meso-colon  and  the  stomach  :  its  right  extremity,  or  head,  is  em- 
braced by  the  duodenum,  separated  from  it  by  the  pancreatico- 
duodenal  arteries ;  behind  the  head  is  the  ductus  communis 
choledochus,  whilst  the  body  is  in  relation  posteriorly  with  the  in- 
ferior vena  cava,  the  superior  mesenteric  vein  and  artery,  the  aorta, 
the  beginning  of  the  vena  portae,  the  crura  of  the  diaphragm,  the 
left  kidney,  the  supra-renal  capsule,  and  the  inferior  mesenteric 
vein ;  its  left  extremity,  or  tail,  touches  the  concavity  of  the  lower 
surface  of  the  spleen,  and  is  in  front  of  the  left  supra-renal  capsule ; 
the  upper  border  is  in  relation  with  the  coeliac  axis,  the  splenic 
artery  and  vein  lying  in  a  groove  in  the  gland,  and  on  the  right 
side  with  the  ascending  portion  of  the  duodenum  and  the  hepatic 
artery ;  the  loiver  border  is  in  relation  with  the  transverse  portion 


476  RELATIONS   OF  THE   KIDNEYS. 

of  the  duodenum,  from  which  it  is  separated  by  the  superior 
mesenteric  vessels,  and  to  the  left  side  with  the  inferior  mesenteric 
vein. 

Its  duct  (canal  of  Wirsung)  runs  from  left  to  right,  near  the 
lower  border  and  anterior  surface  of  the  gland,  and  empties  itself 
into  the  back  part  of  the  descending  portion  of  the  duodenum, 
conjointly  with,  or  close  to,  the  opening  of  the  common  bile-duct. 
It  receives  numerous  branches  from  the  splenic  artery  3  which  runs 
along  its  upper  border  ;  some  from  the  superior  mesenteric,  which 
lies  immediately  beneath  it,  and  others  from  the  gastro-duodenalis. 
The  liver,  stomach,  duodenum,  pancreas,  and 
spleen  should  now  be  collectively  removed.  For 
this  purpose  it  is  necessary  to  cut  through  the  ligaments  of  the 
liver,  the  venae  cavee  hepaticas,  and  the  branches  of  the  coeliac  axis. 
These  viscera,  with  the  remainder  of  the  intestinal  canal,  should  be 
macerated  in  water,  while  you  examine  all  that  is  to  be  seen  at  the 
back  of  the  abdomen :  namely,  the  deep-seated  muscles,  the  aorta,, 
the  inferior  vena  cava,  the  kidneys,  the  lumbar  plexus  of  nerves, 
and  the  sympathetic  nerve. 

KIDNEYS  AND  ^ne  kidneys,  two  large  glands  which  excrete 

URETER,  BELA-  the  urine,  are  situated  in  the  lumbar  region, 
TIONS  OF.  behind  the  peritoneum,  one  on  each  side  of  the 

spine.  They  extend  from  the  eleventh  rib  nearly  as  far  as  the 
crest  of  the  ilium,  and  lie  embedded  in  more  or  less  fat,  on  the 
quadratus  lumborum,  the  psoas,  and  the  crura  of  the  diaphragm. 
The  weight  of  the  kidney  is  from  4^  oz.  to  8  oz.,  the  left  weighing 
a  little  more  than  the  right,  and  the  right  is  somewhat  the  lower 
of  the  two.  Surmounting  each  is  a  small  body,  called  the  supra- 
renal capsule. 

The  anterior  surface  is  convex,  and  the  right  kidney  has  in- 
front,  the  liver,  the  ascending  colon,  the  descending  portion  of  the 
duodenum,  and  the  colica  dextra  artery ;  the  left  kidney  has  in  front, 
the  lower  part  of  the  spleen,  the  cardiac  end  of  the  stomach,  the 
descending  colon,  the  tail  of  the  pancreas,  and  the  colica  sinistra 
artery.  This  explains  how  it  is  that  a  renal  abscess  or  calculus  is 
sometimes  evacuated  by  the  rectum.  Above,  the  right  kidney  is 
in  contact  with  the  under  surface  of  the  liver,  and  its  upper  end 


THE   DIAPHRAGM.  477 

reaches  as  high  as  the  lower  border  of  the  eleventh  rib ;  the  left 
kidney  is  in  contact  above  with  the  spleen,  and  reaches  to  the  level 
of  the  upper  border  of  the  eleventh  rib.  The  posterior  surface  is 
flat  and  lies  on  the  corresponding  crus  of  the  diaphragm,  the  quad- 
ratus  lumborum,  and  the  psoas,  separated  however  by  the  anterior 
layer  of  the  aponeurosis  of  the  transversalis ;  the  outer  border  is 
convex,  and  looks  towards  the  parietes  ;  the  inner  border .  presents 
a  deep  notch,  the  hilum,  continuous  with  a  cavity,  the  sinus, 
through  which  pass  the  renal  artery  and  vein,  the  ureter,  the 
renal  plexus  of  nerves  and  lymphatics,  surrounded  by  connective 
tissue  and  fat.  The  vessels  and  duct  have  the  following  relations  : — 
anteriorly  is  the  renal  vein,  posteriorly  is  the  ureter,  the  renal 
artery  being  between  them.  The  ureter  descends  almost  vertically 
on  the  psoas  muscle,  enters  the  pelvis  over  the  division  of  the  com- 
mon iliac  artery,  and  empties  itself  into  the  lower  part  of  the  bladder 
after  running  obliquely  through  its  coats.  The  kidney,  below,  de- 
scends nearly  as  low  as  the  crest  of  the  ilium,  and  is  not  so  broad  as  the 

DISSECTION.  upper  extremity.     The  kidneys  and  supra-renal 

capsules  must  be  removed  and  reserved  for  further  examination. 

SEMILUNAB  The  semilunar  ganglia,  two  in  number,  are  con- 

GANGLIA.  tained  in  the  solar  plexus,  and  are  situated  one  on 

each  side  of  the  coeliac  axis,  in  the  neighbourhood  of  the  supra- 
renal bodies  ;  that  on  the  right  side  will  be  found  lying  under  the 
vena  cava  inferior.  They  consist  of  irregular  ganglionic  masses. 
Above,  each  ganglion  receives  the  great  splanchnic  nerve  (p.  189), 
and  the  two  ganglia  are  connected  on  their  inner  sides.  Filaments 
are  distributed  to  the  supra-renal  and  renal  plexuses  and  to  the 
plexuses  which  surround  the  branches  of  the  abdominal  aorta. 
The  branches  of  the  solar  plexus  will  be  described  later  on. 

This  is  a  partly  muscular  and  partly  tendinous 
arch,  so  constructed  as  to  form  a  complete  move- 
able  partition  between  the  chest  and  the  abdomen  :  a  floor  for  the 
one,  and  a  roof  for  the  other.  Its  upper  or  thoracic  surface  is  con- 
vex ;  its  lower  or  abdominal,  concave.  On  removing  its  peritoneal 
coat,  and  a  thin  fascial  covering  from  the  transversalis  fascia,  we 
observe  a  broad  tendon  in  the  centre,  and  that  muscular  fibres 

,  a  partition  wall. 


478 


THE    DIAPHRAGM. 


converge  to  it  from  all  sides  (fig.  112).  The  diaphragm  arises,  1. 
From  the  ensiform  cartilage  by  fleshy  fibres ;  2.  From  the  inner 
surfaces  of  the  cartilages  of  the  six  lower  ribs  by  as  many  digita- 
tions,  which  correspond  with  those  of  the  transversalis ;  3.  From 
two  thin  tendinous  arches,  called,  respectively,  the  ligamenta 
arcuata,  externum  and  internum  (the  external  arch  is  the  thickened 
upper  border  of  the  anterior  layer  of  the  transversalis  fascia,  and 
extends  from  the  last  rib  to  the  transverse  process  of  the  first 
lumbar  vertebra,  and  arches  over  the  quadratus  lumborum ;  the 
internal  passes  from  the  transverse  process  of  the  first  lumbar  ver- 

FIG.  112. 


1.  Aorta  passing  be- 

tween the  crura. 

2.  Opening  for  oeso- 

phagus. 

3.  Opening  for  vena 

cava. 


4.  Quadra tus     lum- 

borum. 

5.  Psoas  magnus. 

The  dark  arches 
above  the  quad- 
ratus and  psoas 
are  the  '  arcu- 
ate ligaments.' 


DIAGRAM    OF    THE    DIAPHRAGM,    THE    OPENINGS    IN    IT,    AND    THE    PHRENIC    ARTERIES. 


tebra  to  the  body  of  the  same  vertebra,  and  arches  over  the  psoas)  ; 
and  4.  From  the  front  of  the  bodies  of  the  lumbar  vertebrae  by  two 
elongated  bundles,  called  the  crura  of  the  diaphragm.  Both  crura 
have  tendinous  origins  ;  the  right  crus  is,  however,  a  little  longer 
than  the  left ;  the  former  arises  from  the  first,  second,  and  third 
lumbar  vertebras  and  their  intervening  cartilages;  the  left  does 
not  descend  so  low  by  one  vertebra.  The  inner  fibres  of  each  crus 
decussate ;  those  of  the  right  being  the  more  anterior.  In  their 
decussation  the  fibres  separate  the  aortic  from  the  cesophageal 
openings.  Between  the  two  crura  the  aorta  enters  the  abdomen. 
From  these  various  origins  the  fibres  ascend,  at  first  nearly  ver- 


THE    DIAPHRAGM. 


479 


tically,  and  then  all  arch  inwards,  and  converge  to  be  inserted  into 
the  central  tendon. 

The  central  tendon  is  nearly  the  highest  part  of  the  diaphragm. 
It  presents  a  white  glistening  surface,  owing  to  the  crossing  of  its 
tendinous  fibres ;  its  shape  may  be  compared  to  tha,t  of  a  trefoil 
leaf,  and  it  is  composed  of  a  right  and  left  leaflet  and  a  middle 
leaflet,  separated  from  each  other  by  indentations.  Of  the  three 
leaflets,  the  right  is  the  largest  and  the  left  the  smallest.  The 
chief  point  of  interest  about  the  tendon  is  that,  in  consequence 
of  its  connections  with  the 

pericardium,  below  which  it  Fi3. 113. 

lies  (p.  168),  it  is  always 
maintained  nearly  on  the 
same  level ;  so  that  it  helps 
to  support  the  heart,  and 
serves  as  a  fixed  point  for 
the  insertion  of  the  muscular 
fibres  of  the  diaphragm. 

OPENINGS  IN  There  are 

THE  DIAPHRAGM.  three  large 
openings  in  the  diaphragm 
for  the  transmission  of  the 
aorta,  the  oesophagus,  and 
the  inferior  vena  cava, 
respectively,  and  several 
smaller  apertures  for  the 
transmission  of  nerves  and 

vessels.  The  aortic  opening  is  osseo-aponeurotic,  and  lies  in  the 
middle  line  between  the  two  crura  in  front  of  the  spine ;  it  trans- 
mits, also,  the  vena  azygos  major  and  the  thoracic  duct,  both  of 
which  lie  rather  to  the  right  side  of  the  aorta.  Trace  the  crura 
upwards,  and  observe  that  the  inner  fibres  of  each  cross  each  other 
in  front  of  the  aorta,  somewhat  like  the  letter  X.1  Above  the 
decussation,  and  a  little  to  the  left  of  it,  is  the  oesophageal  opening ; 
this  is  oval  and  entirely  muscular,  and  transmits  the  oesophagus 

1  This  decussation  is  not  always  complete.    But  the  right  crus  always  crosses 
more  or  less  over  the  left,  so  that  the  crura  are  never  strictly  parallel. 


DIAPHRAGM   FROM   ITS   UPPER   SURFACE. 

(The  dotted  lines  show  the  amount  of 
descent  on  contraction.) 


480  FUNCTION  OF  THE  DIAPHRAGM. 

and  the  pneumogastric  nerves.  The  opening  for  the  vena  cava 
(foramen  quadratum)  is  situated  in  the  highest  part  of  the  central 
tendon,  rather  to  the  right  of  the  middle  line,  and  is  quadrate  in 
shape.  Through  this  opening  pass  the  inferior  vena  cava,  some 
lymphatics  from  the  convex  surface  of  the  liver,  and  usually  a 
branch  from  the  right  phrenic  nerve.  Observe  that  the  vein  is 
intimately  connected  to  its  margin,  and  kept  permanently  open. 
Lastly,  there  pass  through  the  cms,  on  each  side,  the  sympathetic 
and  the  greater  and  lesser  splanchnic  nerves ;  and  in  addition,  on 
the  left  side,  the  vena  azygos  minor.  The  arch  of  the  diaphragm, 
in  expiration,  extends  about  as  high  as  the  fifth  rib  on  the  right 
side,  and  the  sixth  rib  on  the  left. 

The  nerves  of  the  diaphragm  are  the  phrenic  (p.  180),  and  the 
five  or  six  lower  intercostal  nerves.  The  diaphragm  also  receives 
minute  filaments  from  the  diaphragmatic  plexuses,  which  come  from 
the  semilunar  ganglia.  On  its  under  surface,  on  the  right  side, 
close  to  the  supra-renal  capsule,  the  plexus  joins  some  branches  of 
the  right  phrenic  nerve,  at  which  spot  there  is  a  small  ganglion 
{ganglion  diaphragmaticum),  from  which  filaments  are  given  off  to 
the  liver,  vena  cava,  and  supra-renal  capsule.  It  is  absent  on  the 
left  side.  Its  blood-vessels  are  the  two  phrenic,  derived  from  the 
aorta,  the  internal  mammary  (p.  159),  and  the  lower  intercostal. 

FUNCTION  OP  The  diaphragm  is  the  great  muscle  concerned 

THE  DIAPHBAGM.  in  inspiration.  It  may  be  said  with  Haller,  that 
it  is  '  musculus  post  cor  nobilissimus.'  During  inspiration  the 
muscular  sides  of  the  diaphragm  contract,  and  become  less  arched 
(as  shown  by  the  dotted  line  in  fig.  113)  ;  the  floor  of  the  chest  sinks 
in  consequence,  and  more  room  is  made  for  the  expansion  of  the 
lungs.  During  expiration  the  diaphragm  relaxes,  and  the  air  is 
expelled,  partly  by  the  elasticity  of  the  lungs  and  the  thoracic  walls, 
partly  by  muscular  action.  This  alternate  sinking  and  rising  of 
the  diaphragm  constitutes  a  chief  part  of  the  mechanism  of  breath- 
ing. But  the  diaphragm  conduces  to  the  performance  of  many 
other  functions.  Acting  in  concert  with  the  abdominal,  muscles, 
it  assists  in  the  expulsion  of  the  fteces  and  the  urine,  also  in  partu- 
rition and  in  vomiting :  for  in  all  these  operations  we  first  take  in 
a  deep  breath,  that  the  diaphragm  may  be  in  a  state  of  contraction, 


COURSE  AND  RELATIONS  OF  THE  ABDOMINAL  AORTA.    481 

and  so  form  a  resisting  surface,  against  which  the  viscera  may  be 
compressed  by  the  abdominal  muscles.  Moreover,  by  its  rapid  or 
spasmodic  contractions  it  is  one  of  the  chief  agents  concerned  in 
laughing,  sneezing,  coughing,  hiccough. 

The  student  should  now  dissect  the  large  vessels 
and  the  muscles  of  the  back  part  of  the  abdomen. 
To  do  so,  the  mesentery  which  lies  in  front  of  the  aorta  and  vena 
cava  is  to  be  removed,  as  well  as  the  fat  and  connective  tissue. 
The  dissection  should  include  the  parietal  branches  of  the  abdo- 
minal aorta ;  afterwards,  its  great  primary  divisions — the  common 
and  external  iliac  arteries — should  be  cleaned  as  far  as  Poupart's 
ligament.  The  quadratus  lumborum,  the  psoas,  and  iliacus  muscles 
should  be  carefully  cleaned,  care  being  taken  not  to  injure  the 
nerves  and  arteries  lying  in  front  of  them  ;  thus,  in  front  of  the 
quadratus  lumborum  are  the  last  dorsal,  the  ilio-hypogastric,  and 
ilio-inguinal  nerves,  which  cross  the  muscle  obliquely  ;  in  front  of 
the  iliacus  are  the  external  cutaneous  and  anterior  crural  nerves  ;  and 
coming  through,  and  then  lying  in  front  of  the  psoas,  is  the  genito- 
crural  nerve,  while  to  the  inner  side  of  the  muscle  is  the  obturator 
nerve.  The  gangliated  cord  of  the  sympathetic  nerves,  situated  on 
each  side  of  the  bodies  of  the  vertebrae,  must  also  be  made  out ; 
and,  lastly,  the  sheath  which  invests  the  psoas  should  be  examined, 
and  the  branches  of  the  lumbar  plexus  preserved  as  they  emerge 
from  beneath  the  outer  border  of  the  muscle. 

Before  examining  the  course  of  the  aorta,  notice  that  a  chain 
of  lymphatic  glands  extends  along  the  brim  of  the  pelvis  and  the 
bodies  of  the  lumbar  vertebras,  following  the  course  of  the  great 
blood-vessels.  Generally  speaking,  they  are  small ;  only  one  here 
and  there  attracts  observation.  They  transmit  the  lymphatics 
from  the  lower  limbs,  the  abdominal  wall,  and  the  testicle ;  and 
all  eventually  lead  to  the  receptacidum  chyli,  or  beginning  of  the 
thoracic  duct  (p.  184).  This  is  usually  found  on  the  right  of 
the  aorta,  close  to  the  second  lumbar  vertebra. 

COURSE  AND  r-^ne  abdominal  aorta  enters  the  abdomen  between 

EELATIONS  OF  THE  the  crura  of  the  diaphragm  in  front  of  the  body  of 
ABDOMINAL  AOETA.  the  }ast  dorsal  vertebra,  and  descends  a  little  to 
the  left  side  of  the  front  of  the  spine,  as  low  as  the  middle  of  the 

II 


482  THE   ABDOMINAL    AORTA. 

fourth  lumbar  vertebra,  where  it  divides  into  the  two  common  iliac 
arteries.  It  follows  the  curve  of  the  lumbar  convexity,  attaining  its 
greatest  curve  on  a  level  with  the  third  lumbar  vertebra.  It  rapidly 
lessens  in  size,  owing  to  the  large  branches  it  gives  off  in  its  course. 
The  division  of  the  aorta  into  the  two  common  iliac  arteries  is  about 
the  level  of  the  highest  point  of  the  crest  of  the  ilium,  and  just 
below  the  left  side  of  the  umbilicus.  The  artery  has  in  front  of  it, 
the  stomach  and  the  lesser  omentum,  the  solar  plexus  surrounding 
the  creliac  axis,  the  splenic  vein,  the  pancreas,  the  transverse  por- 
tion of  the  duodenum,  the  left  renal  vein,  the  mesentery,  the  aortic 
sympathetic  plexus,  and  a  chain  of  lymphatic  glands.  To  the  right 
side  of  it,  lie  the  right  crus  of  the  diaphragm,  the  inferior  vena  cava, 
the  thoracic  duct,  the  vena  azygos,  and  the  right  semilunar  gan- 
glion. To  the  left  side  of  it,  are  the  left  crus,  the  left  semilunar 
ganglion,  and  the  sympathetic  nerves.  Behind,  it  rests  on  the 
receptaculum  chyli,  the  thoracic  duct,  the  left  lumbar  veins,  and 
the  anterior  common  ligament. 

The  branches  of  the  aorta  still  to  be  examined  arise  from  it  in 
pairs — namely,  the  phrenic,  capsular,  renal,  spermatic,  and  lumbar 
(see  diagram,  p.  483). 

PHBENIC  These  arteries  supply  the  under  surface  of  the 

ARTEEIES.  diaphragm,  and  occasionally  arise  separately,  usually 

by  a  common  trunk,  from  the  aorta,  after  its  passage  under  the 
crura  of  the  diaphragm  (fig.  114).  The  right  phrenic  passes  out- 
wards, behind  the  liver  and  the  inferior  vena  cava,  and  then  gets  to 
the  right  side  of  the  caval  opening  in  the  diaphragm ;  the  left  phrenic 
ascends  behind  the  ossophagus,  and  gets  to  the  left  side  of  the  ceso- 
phageal  opening.  Each  ascends,  lying  on  its  corresponding  crus,  as 
far  as  the  central  tendon,  where  it  divides  into  two  branches :  one, 
the  external,  passes  transversely  across  the  tendon  to  the  side  of 
the  diaphragm ;  the  other,  the  internal  branch,  which  seems  to  be 
the  continuation  of  the  artery,  runs  forward  to  the  anterior  part  of 
the  muscle.  Their  first  branches  are  to  the  supra-renal  capsules ; 
then,  the  internal  branch  of  the  right  gives  off  a  small  branch  to 
the  vena  cava,  the  corresponding  branch  of  the  left  sends  one  to 
the  ossophagus.  Moreover  small  branches  are  distributed  respec- 
tively to  the  liver  and  to  the  spleen.  They  inosculate  with  each 


THE   ABDOMINAL   AORTA. 
Fio.  114. 


483 


DIAGRAM   OP   THE   COUKSE   AND   RELATIONS   OF   THE   ABDOMINAL   AORTA   AND 

VENA   CAVA   INFERIOR. 

1.  Ilio-hypogastric  nerve.       2.  Ilio-ingumal  n.       3.  Bxcerual  cutaneous  n.       4.  Anterior  crural  n. 

i  i  2 


484          BRANCHES  OF  THE  ABDOMINAL  AORTA. 

other,  with  the  rnusculo-phrenic  branches  of  the  internal  mammary, 
and  the  intercostal  arteries.  The  right  phrenic  vein  terminates  in 
the  inferior  vena  cava ;  the  left  vein  in  the  renal  vein,  if  not  in  the 
vena  cava. 

SUPKA-EENAL  The  supra-renal  or  capsular  arteries  are  two 

ARTERIES,  very  small  branches,  given  off  from  the  aorta,  one 

on  each  side,  opposite  to  the  superior  mesenteric  artery ;  each  runs 
upon  the  crus  of  the  diaphragm,  the  right  behind  the  inferior  cava, 
and  is  distributed  to  the  supra-renal  body,  inosculating  with 
branches  from  the  phrenic  and  renal  arteries.  The  right  capsular 
vein  terminates  in  the  inferior  cava,  the  left  in  the  left  renal 
vein. 

RENAL  ARTERIES  The  renal  arteries  arise  from  the  aorta  imme- 
AND  VEINS.  diately  below  the  superior  mesenteric  artery,  and 

run  transversely  to  the  hila  of  the  kidneys.  Both  are  covered  by 
their  corresponding  veins.  The  right  is  longer  and  rather  lower 
than  the  left,  and  passes  behind  the  vena  cava.  Each,  after  send- 
ing a  small  branch  to  the  supra-renal  body  and  ureter,  enters  its 
kidney,  not  as  a  single  trunk,  but  by  several  branches,  correspond- 
ing to  the  original  lobes  of  the  organ.  The  renal  veins  lie  in  front 
of  the  arteries,  and  join  the  vena  cava  at  right  angles.  The  left  is 
longer  than  the  right,  and  crosses  over  the  aorta ;  it  also  receives 
the  spermatic,  capsular,  and  the  phrenic  veins  of  its  own  side. 

SPERMATIC  Tne  spermatic  arteries,  two  in  number,  arise 

ARTERIES  AND  from  the  front  of  the  aorta,  a  little  below  the 

VEINS-  renal,  and  pass  to  the  testes  in  the  male  and  to 

the  ovaries  in  the  female.  Each  runs  down  behind  the  peritoneum, 
obliquely  over  the  psoas,  crossing  over  the  ureter,  and  the  front  of 
the  external  iliac  artery  immediately  above  the  crural  arch :  the 
right  artery  in  addition  lying  over  the  vena  cava.  Each  then  passes 
through  the  internal  abdominal  ring  and  inguinal  canal,  with  the 
other  constituents  of  the  spermatic  cord,  to  the  testicle,  where  it 
becomes  tortuous,  and  divides  into  several  branches,  some  of  which 
accompany  the  vas  deferens  and  supply  the  epididymis ;  others 
supply  the  testis  by  piercing  the  tunica  albuginea.  Each  artery  is 
accompanied,  below  the  external  abdominal  ring,  by  a  very  convo- 
luted plexus  of  veins — pampiniform  plexus.  At  the  inner  ring  they 


BRANCHES  OF  THE  ABDOMINAL  AORTA.          485 

terminate  in  two  tortuous  veins,  which  unite  before  they  empty 
themselves,  on  the  right  side,  obliquely,  into  the  vena  cava ;  on  the 
left  side,  at  right  angles,  into  the  left  renal  vein,  after  passing 
behind  the  sigmoid  flexure  of  the  colon.  In  the  female,  the  ovarian 
arteries  descend  towards  the  pelvis,  and  lie  between  the  two  layers 
of  the  broad  ligament  to  be  distributed  to  the  ovaries,  some  branches 
also  going  to  the  Fallopian  tubes,  and  one  to  the  side  of  the  uterus 
to  anastomose  with  the  uterine  artery  of  the  internal  iliac.  They 
likewise  send  small  offsets  to  the  round  ligament,  and  thence  to 
the  skin  of  the  pubes  and  groin. 

LUMBAR  There  are  usually  five  of  these  arteries  on  each 

ARTERIES  AND  side :  four  arise  from  the  back  of  the  aorta,  the 

BRANCHES.  fifth  comes  from  the  arteria  sacra  media.     They 

are  analogous  to  the  intercostal  arteries  on  a  small  scale.  They 
proceed  outwards  over  the  bodies  of  the  vertebra  beneath  the  sym- 
pathetic nerve  and  the  arches  formed  by  the  psoas  muscle;  the 
two  upper  pass  beneath  the  crura  of  the  diaphragm ;  those  on  the 
right  side  being  also  behind  the  vena  cava  inferior.  Passing 
towards  the  intervertebral  foramina,  they,  like  the  intercostals, 
divide  into  dorsal  and  abdominal  branches. 

The  dorsal  branches  pass  between  the  transverse  processes  of 
the  vertebrae,  accompanied  by  the  posterior  branches  of  the  cor- 
responding nerves,  and  are  of  a  size  proportionate  to  the  large 
development  of  the  muscles  of  the  back  which  they  supply.  They 
also  send  spinal  branches,  which  enter  the  spinal  canal  through 
the  intervertebral  foramina ;  some  of  these  are  distributed  to  the 
anterior  part  of  the  cauda  equina,  and  others  to  the  bodies  of  the 
lumbar  vertebrae,  forming  a  series  of  arches  behind  them. 

The  abdominal  branches  all  run  outwards  behind  the  quadra- 
tus  lumborum,  except  the  last,  which  usually  runs  in  front.  After 
supplying  the  quadratus  and  psoas,  they  pass  forwards  between  the 
abdominal  muscles  and  supply  the  walls  of  the  abdomen.1  They 
anastomose,  laterally,  with  the  ilio-lumbar  and  circumflex  iliac 

1  Just  as  the  thoracic  intercostals,  by  communicating  with  the  internal  mam- 
mary, form  an  arterial  ring  round  the  chest,  so  do  the  lumbar,  by  communicating 
with  the  epigastric,  form  a  similar,  though  less  perfect,  ring  round  the  walls  of  the 
abdomen. 


486  INFERIOR  VENA   CAVA. 

arteries  ;  in  front,  with  the  internal  mammary  and  epigastric  arte- 
ries ;  and  above,  with  the  intercostals. 

The  lumbar  veins  empty  themselves  into  the  vena  cava  inferior, 
the  left  passing  behind  the  aorta. 

The  arteria  sacra  media,  a  diminutive  continuation  of  the  aorta, 
proceeds  from  its  bifurcation,  and  runs  down,  behind  the  left 
common  iliac  vein  and  in  front  of  the  sacrum,  to  the  coccyx.  It 
sends  off  the  fifth  lumbar  artery,  and  lateral  branches,  which  ana- 
stomose with  the  lateral  sacral  arteries ;  it  also  supplies  small  vessels 
to  the  posterior  part  of  the  rectum,  which  run  forwards  between 
the  layers  of  the  meso-rectum.  In  close  connection  with  the  ter- 
minal branch  of  this  artery  at  the  tip  of  the  coccyx  is  a  small 
roundish  body  called  the  coccygeal  or  Luschka's  gland}-  It  is  about 
the  size  of  a  pea,  and  is  placed  between  the  levatores  ani  and 
the  sphincter  ani.  It  is  probably  composed  of  a  plexus  of  small 
arteries,  which  are  surrounded  by  one  or  more  layers  of  granular 
polygonal  cells.  The  body  itself  is  invested  by  connective  tissue, 
in  which  also  some  branches  from  the  ganglion  impar  have  been 
traced.  This  gland  should  be  considered  as  an  arterial  gland,  of 
which  the  intercarotic  ganglion  is  another  example. 

The  vena  sacra  media  empties  itself  into  the  left  common  iliac 
vein. 

VENA  CAVA  The  vena  cava  inferior  is  formed  by  the  junction 

INFERIOR.  of  the  two  common  iliac  veins,  a  little  to  the  right 

side  of  the  intervertebral  cartilage  between  the  fourth  and  fifth 
lumbar  vertebrae.  It  ascends  in  front  of  the  spine,  in  the  greater 
part  of  its  course  lying  to  the  right  of  the  aorta.  As  it  approaches 
the  diaphragm,  the  vena  cava  inclines  a  little  to  the  right,  sepa- 
rated from  the  aorta  by  the  right  crus  of  the  diaphragm.  It  is 
then  received  into  a  deep  groove  on  the  posterior  border  of  the 
liver,  and  afterwards  passes  through  the  tendinous  opening  in  the 
diaphragm  to  reach  the  right  auricle  of  the  heart.  Its  relations, 
beginning  from  below,  are — in  front,  the  mesentery,  the  third  part 
of  the  duodenum,  the  pancreas,  the  right  spermatic  artery,  the 
portal  vein,  and  the  liver ;  behind  it  are  the  right  renal  artery,  the 

1  Luschka,  Anatomic  des  Menschen,  1864,.  vol.  ii.  pt.  2,  p.  187 ;  Arnold,  Virchow 
ArcMv,  1864,  1865,  and  1866  ;  Callender,  British  Medical  Journal,  June  13,  1874. 


PSOAS   AND   ILIAC   FASCIAE.  487 

right  lumbar  arteries,  the  sympathetic  of  the  right  side,  and  the 
right  phrenic  artery ;  on  its  left  is  the  aorta,  and  higher  up  the  right 
crus.  It  receives  the  lumbar  veins,  the  right  spermatic  (the  left 
joins  the  renal),  the  renal,  the  right  supra-renal,  the  right  phrenic, 
and  the  hepatic  veins  which  are  usually  three  in  number,  one  each 
from  the  right  and  left  lobes,  and  one  from  the  lobulus  Spigelii. 

The  student  should  now  direct  his  attention  to  the  three  large 
muscles  which  are  seen  at  the  back  of  the  abdomen :  the  quadratus 
lumborum  situated  between  the  last  rib  and  the  crest  of  the  ilium ; 
the  iliacus  occupying  the  iliac  fossa ;  and  the  psoas  magnus  passing 
from  the  sides  of  the  lumbar  vertebras,  along  the  brim  of  the  pelvis, 
and  beneath  Poupart's  ligament,  to  be  inserted  into  the  lesser  tro- 
chanter  of  the  femur.  The  nerves  should  at  the  same  time  be 
cleaned,  and,  if  more  convenient,  the  student  might  dissect  the 
muscles  on  one  side,  and  the  nerves  and  arteries  on  the  other. 

The   fascia    covering    the    iliacus    and    psoas 
PSOAS  FASCIA.  .       .  °.  ,  r 

muscles  is  seen  to  be  thin  above  and  thicker  below. 

It  consists  of  two  portions,  the  psoas  and  the  iliac  fascia.  The  psoas 
fascia  is  attached  to  the  sides  of  the  lumbar  vertebras  and  their 
intervertebral  cartilages,  internally  to  the  sacrum,  and  above  to 
the  ligamentum  arcuatum  internum  ;  externally  it  is  thinner,  and 
is  continuous  with  the  fascia  lumborum.  It  is  this  sheath  which 
determines  the  ordinary  course  of  a  psoas  abscess — namely,  be- 
neath the  crural  arch  into  the  upper  part  of  the  thigh  ;  for  it  is  a 
rare  exception  when  the  matter  travels  into  the  pelvis. 

The  iliac  fascia  covers  the  iliacus  muscle,  and 
is  attached  to  the  inner  lip  of  the  crest  of  the 
ilium,  and  to  the  brim  of  the  pelvis,  through  its  connection 
with  the  sheath  of  the  psoas  and  the  tendinous  insertion  of  the 
psoas  parvus.  Its  most  important  attachment  is  to  the  outer  half 
of  the  crural  arch,  and  it  is  here  directly  continuous  with  the  fascia 
transversalis  (p.  435),  so  that  together  they  present  an  effectual 
barrier  to  the  escape  of  intestine  beneath  this  part  of  the  arch.1 
On  the  inner  half  of  Poupart's  ligament,  these  two  fascise  are 
separated  by  the  femoral  vessels,  so  that  the  fascia  transversalis 

1  The  iliac  fossae  are  liable  to  be  the  seat  of  suppuration,  and  the  course  which 
the  pus  takes  depends  upon  its  position  with  regard  to  the  iliac  fascia.  If  the 


488  PSOAS   MAGNUS. 

lies  in  front  of,  the  fascia  iliaca  behind  the  artery  and  vein,  thus 
forming  their  sheath  as  they  pass  down  the  thigh.  This  portion  of 
the  iliac  fascia  also  forms  a  sheath  for  the  psoas  and  iliacus  as  far 
as  their  insertion,  and  becomes  continuous  with  the  iliac  portion  of 
the  fascia  lata.  Internally  the  iliac  fascia  is  attached  to  the  linea 
ilio-pectinea,  where  it  becomes  continuous  with  the  pubic  portion 
of  the  fascia  lata.  The  external  iliac  artery  and  vein  lie  in  front 
of  the  fascia,  while  the  anterior  crural  nerve  is  behind  it. 

These  fasciae  are  now  to  be  dissected  off,  when  the  psoas  and 
iliacus  will  be  completely  exposed. 

This  long  muscle  arises  by  five  muscular  fas- 
PSOAS  MAGNUS.          .      ,.    „  ,,  *     «    u 

ciculi  from  the   transverse    processes   or   all   the 

lumbar  vertebrae,  also  from  the  bodies  of  the  last  dorsal  and  all  the 
lumbar  vertebras  and  their  intervening  fibro-cartilages,  but  only 
from  the  projecting  borders  of  their  bodies,  not  from  the  central 
concave  part ;  here  the  fibres  arise  from  tendinous  arches  thrown 
over  the  lumbar  vessels.  The  muscle  descends  vertically  along  the 
brim  of  the  pelvis,  beneath  the  crural  arch  into  the  thigh,  and  is 
inserted  by  a  strong  tendon  into  the  back  part  of  the  lesser  tro- 
chanter  of  the  femur.  In  front,  the  psoas  has,  in  relation  with  it, 
the  psoas  fascia,  the  ligamentum  arcuatum  internum,  the  common 
and  external  iliac  artery  and  vein,  the  kidney  and  ureter,  the 
spermatic  vessels,  the  genito-crural  nerve,  the  colon,  the  renal 
vessels,  the  vas  deferens,  the  psoas  parvus  when  present ;  behind  it, 
are  the  ilium,  the  transverse  processes  of  the  lumbar  vertebras,  the 
quadratus  lumborum,  the  anterior  layer  of  the  transversalis  apo- 
neurosis,  the  lumbar  plexus  of  nerves,  and  the  obturator  nerve, 
which  lower  down  runs  along  the  inner  border  of  the  muscle  ;  on 
its  inner  side,  are — the  crus  of  the  diaphragm,  the  bodies  of  the 
lumbar  vertebras,  the  lumbar  arteries,  the  lumbar  glands,  and  the 
sympathetic  nerves ;  to  the  inner  side  of  the  left  psoas  is  the  aorta, 
and  to  that  of  the  right  psoas  is  the  inferior  vena  cava.  Towards  its 
insertion  the  tendon  of  the  psoas  lies  bet  ween  the  iliacus  and  pectineus . 

pus  be  seated  in  the  loose  cellular  tissue  between  the  peritoneum  and  the  fascia,  it 
usually  advances  just  above  the  crest  of  the  ilium,  or  towards  the  groin  through 
the  inguinal  canal ;  but,  if  seated  beneath  the  fascia,  the  matter  usually  makes  its 
way  under  the  crural  arch  towards  the  upper  and  outer  part  of  the  thigh. 


ILIACUS.  489 

As  it  passes  under  the  crural  arch,  the  tendon  of  the  psoas  lies 
immediately  over  the  capsule  of  the  hip-joint,  and  there  is  a  large 
bursa  between  them  to  facilitate  the  play  of  the  tendon.  It  should 
be  borne  in  mind  that  occasionally,  even  in  young  subjects,  but 
more  frequently  in  old  ones,  in  consequence  of  wear  and  tear,  this 
bursa  communicates  with  the  hip-joint.  The  fact  is  important, 
for  it  explains  how  a  psoas  abscess  sometimes  makes  its  way  into 
the  hip-joint,  a  result  frequently  fatal. 

Once  in  about  eight  or  ten  subjects  there  is  a 
PSOAS  PAKVUS.  ,,  ,         ,,    ,  ° 

small  muscle  called  the  psoas  parvus  placed  super- 
ficially to  the  preceding  muscle.  It  arises  from  the  sides  of  the 
bodies  of  the  last  dorsal  and  the  first  lumbar  vertebras,  and  the 
intervening  fibro-cartilage ;  thence,  descending  in  front,  and  to  the 
inner  side  of  the  psoas  magnus,  it  ends  in  a  long  flat  tendon,  which 
spreads  out,  and  is  inserted  into  the  linea  ilio-pectinea. 

The  iliacus  arises  from  the  iliac  fossa,  the  inner 

lip  of  the  crest  of  the  ilium,  the  ilio-lumbar  liga- 
ment,1 the  base  of  the  sacrum,  and  the  anterior  superior  spine  of 
the  ilium ;  below,  also  from  the  anterior  inferior  spine  and  from 
the  capsule  of  the  hip-joint.  The  fibres  converge  beneath  the 
crural  arch,  and  are  inserted  mainly  into  the  outer  side  of  the 
tendon  of  the  psoas,  and  partly  into  the  triangular  surface  of  the 
femur,  below  and  anterior  to  the  lesser  trochanter.  Thus  the  two 
muscles,  so  far  as  their  action  goes,  may  be  considered  as  one,  and 
are  sometimes  called  the  ilio-psoas. 

The  iliacus  in  the  abdomen  is  in  relation,  in  front,  with  the 
iliac  fascia,  the  external  cutaneous  and  anterior  crural  nerves,  with 
the  caacum  on  the  right,  and  with  the  sigmoid  flexure  on  the  left 
side ;  behind,  it  is  in  contact  with  bone ;  on  its  inner  side  is  the 
psoas.  In  the  thigh  it  is  in  relation,  in  front,  with  the  rectus, 
the  sartorius,  the  fascia  lata,  the  anterior  crural  nerve,  the  pro- 
funda  femoris  and  the  external  circumflex  arteries ;  behind,  with 
the  capsular  ligament  of  the  hip-joint ;  on  the  inner  side,  with 
the  psoas ;  and  on  the  outer,  with  the  crureus  and  vastus  internus 
muscles. 

1  This  ligament  extends  from  the  transverse  process  of  the  last  lumbar  vertebra 
to  the  ilium. 


490  QUADRATUS   LUMBORUM. 

The  combined  action  of  the  psoas  and  iliacus  is  to  assist  in 
raising  the  body  from  the  recumbent  position,  and  to  fix  the  pelvis 
steadily  on  the  thigh :  this  supposes  the  fixed  point  to  be  at  the 
trochanter  minor.  If  the  fixed  point  be  at  the  spine,  then  the 
muscle  flexes  and  rotates  the  femur  outwards.  It  is  this  action 
which  often  occasions  so  much  displacement  in  fractures  of  the 
upper  third  of  the  femur. 

QUADRATUS  This  quadrilateral  muscle  extends  from  the  crest 

LUMBORUM  AND  of  the  ilium  to  the  last  rib,  and  is  contained  in  a 
ITS  SHEATH.  sheath  formed  for  it  by  the  aponeurotic  origin 

of  the  transversalis  (p.  431).  The  anterior  layer  of  its  sheath 
is  attached  to  the  roots  of  the  transverse  processes  of  the  lumbar 
vertebrae,  and  the  posterior  layer  to  their  summits.  The  muscle, 
broader  below  than  above,  arises  by  two  portions — one  from  the 
ilio-lumbar  ligament  and  from  the  crest  of  the  ilium  for  two  inches 
external  to  it,  and  is  inserted  into  the  last  rib,  and  by  tendinous 
slips  into  the  apices  of  the  transverse  processes  of  the  upper  four 
lumbar  vertebras ;  the  other  portion  of  the  muscle  arises  from  the 
transverse  processes  of  the  third,  fourth,  and  fifth  lumbar  vertebrae, 
and  is  inserted  into  the  lower  margin  of  the  last  rib,  in  front  of  the 
preceding  portion.  The  principal  use  of  the  muscle  is  to  steady 
the  spine ;  it  also  steadies  the  last  rib,  and  enables  it  to  serve 
as  a  fixed  point  for  the  action  of  the  intercostal  muscles  and  the 
diaphragm.1 

By  raising  the  quadratus,  we  observe  the  aponeurotic  origin 
of  the  transversalis  from  the  summits  of  the  transverse  processes : 
this  constitutes  the  posterior  part  of  its  sheath,  and  separates  the 
muscle  from  the  erector  spinae. 

COMMON  ILIAC  The  abdominal  aorta  divides,  in  front  of  the  left 

ARTERIES  AND  side  of  the  fourth  lumbar  vertebra,  into  two  great 

VEINS-  branches,  termed  the  common  iliac  arteries.     They 

1  The  respective  attachments  of  the  quadratus  lumborum,  the  crossing  of  its 
fibres,  and  its  mode  of  action,  lead  to  the  inference  that  it  is  a  large  intercostal 
muscle.  It  is  worth  remembering  that  the  outer  edge  of  the  quadratus  lumborum, 
in  a  well-grown  adult,  is  about  three  inches  from  the  spines  of  the  lumbar  vertebra, 
and  midway  between  the  last  rib  and  the  crest  of  the  ilium.  It  is  just  outside  the 
edge  of  this  muscle  that  we  can  cut  down  to  open  the  large  bowel  without  wounding 
the  peritoneum. 


COMMON  ILIAC   ARTERIES.  491 

diverge  at  an  acute  angle,  and,  after  a  course  of  about  two  inches 
downwards  and  outwards,  each  divides,  over  the  sacro-iliac  sym- 
physis,  into  the  external  and  internal  iliac  arteries.  They  lie 
upon  the  bodies  of  the  fourth  and  fifth  lumbar  vertebrae.  The 
right  common  iliac  is  rather  larger  than  the  left.  They  are  covered 
in  front  by  peritoneum,  they  are  crossed  by  branches  of  the  sym- 
pathetic to  form  the  hypogastric  plexus,  and  they  are  crossed  at  or 
near  their  division  by  the  ureters  ;  on  the  outer  side  they  are  in 
relation  with  the  psoas.  So  far,  then,  the  relations  of  both  common 
iliac  arteries  are  similar.  But  each  has  its  special  relations  as 
follows  : — 

The  special  relations  of  the  right  common  iliac  are,  that  it  has 
behind  it  the  two  common  iliac  veins,  which  separate  it  from  the 
fifth  lumbar  vertebra ;  on  its  outer  side,  it  has,  above,  the  inferior 
vena  cava ;  below,  the  right  common  iliac  vein. 

The  special  relations  of  the  left  common  iliac  are,  that  it  has 
in  front  of  it  the  end  of  the  sigmoid  flexure  of  the  colon,  and 
the  superior  haemorrhoidal  artery;  and  to  its  inner  side,  the  left 
common  iliac  vein,  which  gradually  gets  more  behind  it  towards 
the  sacro-iliac  symphysis. 

The  relations  of  these  arteries  with  regard  to  their  correspond- 
ing veins  are,  practically,  important  in  reference  to  the  operation 
of  tying  them.  This  operation  is,  obviously,  easier  on  the  left  side 
than  the  right.1 

If  the  common  iliac  artery  were  ligatured,  the  collateral  cir- 
culation would  be  maintained  through  the  following  vessels :  by 
the  internal  mammary  anastomosing  with  the  deep  epigastric  a. ; 
by  the  lumbar  arteries  with  the  circumflex  iliac  and  the  ilio- 
lumbar  a. ;  by  the  lumbar  with  the  gluteal ;  by  the  middle  sacral 

1  The  length  of  the  common  iliac  artery  is  apt  to  vary  in  different  persons. 
We  have  seen  it  from  three-fourths  of  an  inch  to  three  and  a  half  inches  long. 
These  varieties  may  arise  either  from  a  high  division  of  the  aorta,  or  a  low  division 
of  the  common  iliac,  or  both.  It  is  impossible  to  ascertain,  beforehand,  its  length 
in  any  given  instance,  as  there  is  no  necessary  relation  between  its  length  and  the 
height  of  the  adult  individual.  It  is  often  very  short  in  men  of  tall  stature,  and 
vice  versa.  The  left  is  usually  described  as  rather  longer  than  the  right ;  but,  from 
the  examination  of  100  bodies,  our  conclusion  is  that  their  average  length  is  the 
same. 


492  EXTERNAL   ILIAC   ARTERY. 

with  the  lateral  sacral  a. ;  by  the  spermatic  with  the  deferential, 
cremasteric,  external  pudic  and  superficial  perineal  arteries ;  by 
the  superior  hgemorrhoidal  with  the  middle  and  inferior  haemor- 
rhoidal  a. ;  by  the  lower  intercostals  with  the  epigastric  a.  (super- 
ficial and  deep) ;  and  by  the  middle  and  the  inferior  ha3niorrhoidal, 
the  pudic  and  its  branches,  and  the  vesical  arteries  communicating 
in  the  middle  line  with  the  corresponding  branches  of  the  opposite 
side. 

EXTERNAL  The  external  iliac  artery,  the  continuation  of  the 

ILIAC  AKTERY.  preceding  artery,  passes  along  the  brim  of  the 

pelvis,  first  on  the  inner  side,  and  then  in  front  of  the  psoas. 
Lower  down  it  passes  under  the  crural  arch,  midway  between  the 
^anterior  superior  spine  of  the  ilium  and  the  symphysis  pubis,  where 
it  takes  the  name  of  femoral.  The  artery  has  in  front  of  it,  the 
peritoneum,  the  intestines,  and  a  sheath  derived  from  the  iliac 
fascia  investing  the  artery  and  the  vein  ;  it  has  also  the  spermatic 
vessels  in  front,  and  it  is  crossed  by  a  branch  of  the  genito-crural 
nerve,  the  deep  circumflexa  ilii  vein  and  the  vas  deferens  ;  behind, 
it  is  in  relation  with  the  psoas  magnus  and  corresponding  vein, 
which  lies  also  on  the  inner  side  of  the  artery ;  the  iliac  fascia  also 
lies  behind  the  vessels,  but  a  thin  layer  of  fascia  derived  from  it  is 
continued  over  them ;  internally,  it  has  the  corresponding  vein,  and 
low  down  towards  Poupart's  ligament,  the  vas  deferens;  externally, 
it  has  the  psoas  magnus  and  the  iliac  fascia.  In  front  of,  and  on 
the  inner  side  of  the  artery  are  a  chain  of  lymphatic  glands. 
The  branches  given  off  by  this  artery  are  : — 

a.  Small  branches  to  the  psoas  and  lymphatic  glands. 

b.  The  deep  epigastric,  already  described  (p.  437). 

c.  The  deep  circumflexa  ilii,  which  arises  from  the  outer  side 
of  the  artery,  just  above  the  crural  arch,  and,  ascending  upwards 
towards  the  anterior  superior  spine  of  the  ilium  in  a  sheath  formed 
by  the  fascia  iliaca,  runs  along  the  inner  aspect  of  the  iliac  crest, 
and  subsequently  perforates  the  transversalis  muscle.1     In  the  dis- 
section of  the  abdominal  muscles  (p.  430),  the  continuation  of  it 
was  seen  skirting   the    crest  of  the  ilium  between   the  internal 
oblique   and   the   transversalis,  and   sending   a   branch   upwards 

1  The  course  of  this  artery  should  be  borne  in  mind  in  opening  iliac  abscesses. 


LIGATURE   OF   THE   EXTERNAL   ILIAC   ARTERY.  493 

between  these  muscles  for  their  supply.  The  main  trunk,  much 
reduced  in  size,  inosculates  with  the  ilio-lumbar  derived  from  the 
internal  iliac. 

LIGATUKE  OF  The  best  way  of  tying  the  external  iliac  is  to 

THE  EXTERNAL  make  a  curved  incision  at  the  lower  part  of  the 
ILIAC-  abdomen,  beginning  a  little  above  the  middle  of 

the  crural  arch,  and  ending  about  an  inch  to  the  inner  side  of  the 
spine  of  the  ilium.  The  strata  of  the  abdominal  muscles,  with  the 
fascia  transversalis,  should  then  be  divided  to  the  same  extent ; 
after  which,  the  peritoneum  with  the  spermatic  vessels  must  be 
separated  by  the  fingers  from  the  iliac  fossa.  It  is  necessary  to 
make  a  small  incision  through  the  sheath  of  the  vessels,  to  facilitate 
the  passage  of  the  needle.  Remember  that  the  vein  is  closely  con- 
nected to  its  inner  side,1  that  the  genito-crural  nerve  is  not  far  off, 
and  that  the  circumflex  iliac  vein  crosses  the  artery  just  above 
Poupart's  ligament. 

After  ligature  of  the  artery  the  collateral  circulation  would  be 
maintained  by  anastomoses  between  the  internal  mammary  and  the 
deep  epigastric  ;  between  the  lumbar  arteries  and  the  circumflex 
iliac ;  between  the  pubic  branch  of  the  obturator  and  the  branch  of 
the  epigastric  ;  between  the  gluteal  and  the  internal  and  external 
circumflex ;  between  the  sciatic  and  the  first  perforating  and  the 
internal  circumflex ;  between  the  obturator  and  the  internal  cir- 
cumflex ;  between  the  spermatic,  the  deferential,  and  the  cremasteric 

1  This  relative  position  of  the  vessels  does  not  always  exist.  In  old  subjects, 
less  frequently  in  adults,  it  is  sometimes  found  that  the  external  iliac  artery  runs 
very  tortuously,  instead  of  nearly  straight,  along  the  brim  of  the  pelvis.  But  the 
vein  does  not  follow  the  artery  in  its  windings,  and  may  possibly  lie  outside  the 
artery  just  where  we  propose  to  place  the  ligature. 

The  mode  of  performing  the  operation  described  in  the  text  is  recommended  by 
Sir  A.  Cooper.  Mr.  Abernethy,  however,  who  first  set  the  example  of  tying  this 
artery  in  1796,  adopted  a  somewhat  different  proceeding.  He  says:  '  I  first  made 
an  incision  about  three  inches  in  length  through  the  integuments  of  the  abdomen, 
in  the  direction  of  the  artery,  and  thus  laid  bare  the  aponeurosis  of  the  external 
oblique  muscle,  which  I  next  divided  from  its  connection  with  Poupart's  ligament, 
in  the  direction  of  the  external  wound,  for  the  extent  of  about  two  inches.  The 
margins  of  the  internal  oblique  and  transversalis  muscles  being  thus  exposed,  I 
introduced  my  finger  beneath  them  for  the  protection  of  the  peritoneum,  and  then 
divided  them.  Next,  with  my  hand,  I  pushed  the  peritoneum  and  its  contents 
upwards  and  inwards,  and  took  hold  of  the  artery.' 


494  SYMPATHETIC   IN   THE   ABDOMEN. 

and  the  external  pudic ;  between  the  lower  intercostal s  and  the 
lumbar  arteries  and  the  epigastric  artery. 

SYMPATHETIC  The  general  plan  upon  which  the  sympathetic 

NERVE,  nerve  is  arranged  has  been  Noticed  in  the  dissec- 

tion of  the  neck  (p.  151).  The  lumbar  portion  of  it  must  now  be 
examined. 

The  lumbar  portion  of  the  sympathetic  descends  on  each  side  in 
front  of  the  bodies  of  the  lumbar  vertebras,  along  the  inner  border 
of  the  psoas.  The  nerve  has  an  oval  ganglion  of  greyish  colour, 
opposite  each  lumbar  vertebra,  so  that  there  are  either  four  or  five 
of  them  on  each  side.  These  ganglia  are  connected  together  by 
small  filaments  of  a  white  colour,  and  each  ganglion  receives,  on  its 
outer  side,  two  branches  from  the  corresponding  spinal  nerve,  as  in 
the  chest ;  other  branches  pass  inwards,  and  form  in  front  of  the 
aorta — the  aortic  plexus  ;  and  some  pass  downwards  over  the  com- 
mon iliac  arteries  to  form  the  hypogastric  plexus. 

SOLAR  PLEXUS  The  solar  or  epigastric  plexus  is  situated  in  front 

AND  THE  SEMI-  of  the  aorta,  and  surrounds  the  coeliac  axis  in  a 
LUNAR  GANGLIA.  dense  network  of  nerve  filaments,  in  which  are 
several  ganglia.  It  receives  the  great  splanchnic  nerves,  part  of 
the  lesser  splanchnic,  and  some  branches  from  the  pneumogastric 
nerves.  The  solar  plexus  gives  off  filaments  which  form  plexuses 
surrounding  the  various  branches  of  the  abdominal  aorta,  and  are 
as  follows : — 

Diaphragmatic.  Supra-renal. 

Coeliac.  Eenal. 

Gastric.  Spermatic. 

Hepatic.  Superior  mesenteric. 

Splenic.  Inferior  mesenteric. 
Hypogastric. 

The  diaphragmatic  plexus  is  derived  from  the  upper  part  of  the 
semilunar  ganglion,  and  is  larger  on  the  right  than  on  the  left  side. 
It  joins  with  some  filaments  of  the  phrenic  nerve,  and,  whilst  in 
relation  with  the  supra-renal  body,  it  gives  off  some  branches  to  it. 
The  right  plexus  has  a  small  ganglion  in  it — diaphragmatic  ganglion 
— and  sends  off  filaments  to  the  vena  cava  inferior  and  to  the 
hepatic  plexus. 


HYPOGASTRIC   PLEXUS.  495 

The  cceliac  plexus  receives  branches  from  the  lesser  splanchnic 
nerve,  and,  on  the  left  side,  it  receives  a  filament  from  the  right 
pneumogastric  nerve.  It  divides  into  the  gastric,  hepatic,  and 
splenic  plexuses,  which  ramify  on  the  corresponding  arteries  and 
their  branches;  the  gastric  plexus  receives  in  addition  filaments 
from  the  pneumogastric  nerves ;  the  hepatic  plexus,  the  largest,  is 
joined  by  branches  from  the  left  pneumogastric  and  right  phrenic 
nerves,  and  it  distributes  filaments  to  the  right  supra-renal  plexus ; 
the  splenic  plexus  is  formed  by  branches  from  the  left  semilunar 
ganglion  and  the  right  pneumogastric  nerve. 

The  supra-renal  plexus  is  formed  by  branches  from  the  solar 
plexus,  the  semilunar  ganglion,  and  the  diaphragmatic  plexus,  and 
is  larger  on  the  right  than  on  the  left  side. 

The  renal  plexus  consists  of  numerous  filaments  from  the  semi- 
lunar  ganglion,  and  from  the  solar  and  aortic  plexuses ;  it  is  also 
reinforced  by  branches  from  the  splanchnic  nerves.  From  this 
plexus  is  given  off — 

The  spermatic  plexus,  which  likewise  receives  filaments  lower 
down  from  the  aortic  plexus  ;  in  the  female,  it  takes  the  name  of 
the  ovarian  plexus. 

The  superior  mesenteric  plexus  receives,  in  addition  to  its 
branches  from  the  solar  plexus,  some  filaments  from  the  right 
pneumogastric  nerve  and  the  cceliac  plexus.  It  is  the  densest  of 
all  the  plexuses  derived  from  the  solar  plexus,  and  it  breaks  up  into 
secondary  plexuses  corresponding  to  the  branches  of  the  artery  of 
the  same  name. 

The  inferior  mesenteric  plexus  comes  mainly  from  the  left  side 
of  the  aortic  plexus. 

HYPOGASTBIC  The  Jiypogastric  plexus  is  situated  between  the 

PLEXUS.  common  iliac  arteries,  on  the  last  lumbar  vertebra 

and  the  sacrum.  It  consists  of  an  intricate  interlacement  of  sym- 
pathetic filaments,  which  pass  down  into  the  pelvis,  for  the  supply 
of  the  pelvic  viscera.  Although  this  plexus  is  so  intricate,  it  pre- 
sents no  distinct  ganglia.  As  it  passes  down  it  receives  branches 
from  some  of  the  spinal  nerves,  but  mainly  from  the  third  and  fourth 
sacral  nerves.  From  this  large  plexus  are  derived  secondary 
plexuses,  which  ramify  around  branches  of  the  internal  iliac  artery : 


496  LUMBAR   PLEXUS. 

thus  there  are,  the  inferior  hasmorrhoidal  plexus,  the  vesical,  the 
uterine,  the  ovarian,  the  prostatic,  and  the  vaginal ;  all  of  which 
send  filaments  which  accompany  the  smallest  branches  of  the 
arteries. 

LUMBAB  The  lumbar  plexus  is  formed  by  the  union  of  the 

PLEXUS  OF  anterior  branches  of  the  four  upper  lumbar  nerves, 

NEKVES.  an^  js  frequently  connected  with  the  last  dorsal 

nerve  by  a  small  loop — the  dorsi-lumbar  nerve.  The  fifth  does  not 
enter  into  the  formation  of  this  plexus,  but  joins  the  sacral  plexus 
under  the  name  of  the  lumbo-sacral  cord.  The  plexus  lies  over  the 
transverse  processes  of  the  corresponding  vertebrae,  embedded  in 
the  substance  of  the  psoas,  so  that  this  muscle  must  be  dissected 
away  before  the  plexus  can  be  seen.  .  Like  the  brachial  plexus,  the 
nerves  composing  it  successively  increase  in  size  from  above.  Its 
branches  are  five  in  number,  and  arise  in  the  following  order 
(fig.  115). 

a.  The  first  lumbar  nerve  generally  divides  into  two  branches  ; 
the  upper  being  the  ilio-hypogastric,  the  lower  the  ilio-inguinal. 
They  pass  downwards  and  outwards  nearly  parallel  with  each  other, 
cross  obliquely  over  the  quadratus  lumborurn  to  the  crest  of  the 
ilium,  and  then  separate. 

The  ilio-hypogastric  nerve  emerges  from  the  outer  border  of  the 
psoas,  and,  crossing  the  quadratus  lumborum,  passes  forwards  to 
the  crest  of  the  ilium,  where  it  pierces  the  transversalis,  and  divides 
into  its  two  terminal  branches — the  iliac  branch,  which  pierces  the 
internal  and  external  oblique  muscles,  and  supplies  the  skin  over 
the  gluteal  region,  behind  the  last  dorsal  nerve ;  and  the  hypogastric 
branch,  which  runs  forwards  between  the  transversalis  and  internal 
oblique,  and  then  perforates  the  aponeurosis  of  the  external  oblique 
to  supply  the  skin  of  the  hypogastric  region. 

The  ilio-inguinal  nerve — the  smaller — comes  through  the  psoas, 
and  perforates  the  transversalis  close  to  the  front  of  the  iliac  crest, 
where  it  communicates  with  the  preceding  nerve.  It  then  pierces 
the  internal  oblique,  and,  lying  in  front  of  the  spermatic  cord, 
comes  out  through  the  external  abdominal  ring,  and  supplies  the 
skin  of  the  inner  and  upper  part  of  the  thigh,  of  the  penis  and 
scrotum  in  the  male,  and  of  the  labium  in  the  female. 


LUMBAR   PLEXUS. 


497 


The  genito-crural  nerve  is  small,  and  comes  from  the  second 
lumbar,  and  by  a  few  filaments  from  the  communicating  branch  of 
the  first.  After  perforating  the  psoas,  it  lies  for  a  short  distance 
upon  its  anterior  surface,  and  then  runs  down  along  the  outer  side 
of  the  external  iliac  artery.  Near  the  crural  arch  it  divides  into 
the  genital  branch  (</),  which  runs  down  on  the  external  iliac 
artery,  and,  piercing  the  fascia  transversalis,  descends  through  the 
internal  abdominal  ring,  along  the  inguinal  canal,  on  the  posterior 

FIG.  115. 


n..  Ilio-hypogastric  n. 
ft.  Ilio-lnguinal  n. 

c.  External  cutaneous  n. 

d.  Anterior  crural  n. 

e.  Crural  branch  of  genito- 

crural  n. 

/.  Obturator  n. 

g.  Genital  branch  of  genito- 
crural  n. 

h.  Lumbo-sacral  n. 


1.  First  lumbar  n. 

2.  Second     „    „ 

3.  Third       „    „ 

4.  Fourth     „    „ 
6.  Fifth 


PLAN   OF   THE    LUMBAR   PLEXUS  AND   BRANCHES. 

aspect  of  the  spermatic  cord  ;  it  supplies  the  cremaster  in  the 
male,  and  the  round  ligament  in  the  female ;  and  the  crural 
branch  (e),  which  proceeds  under  the  crural  arch,  enters  the  sheath 
of  the  femoral  vessels,  and,  piercing  the  anterior  layer  of  the  sheath, 
just  external  to  the  artery,  is  lost  in  the  skin  of  the  upper  part 
of  the  front  of  the  thigh ;  here  it  communicates  with  the  middle 
cutaneous  nerve  and  supplies  also  a  few  filaments  to  the  femoral 
artery,  where  it  perforates  the  sheath  of  that  vessel. 

K  K 


498  LUMBAR    PLEXUS. 

The  external  cutaneous  nerve  of  the  thigh  (c)  is  generally  de- 
rived from  the  loop  between  the  second  and  third  lumbar  nerves. 
It  runs  through  the  psoas,  then,  crossing  obliquely  over  the  iliacus 
towards  the  anterior  superior  spine  of  the  ilium,  passes  beneath 
the  crural  arch,  and  is  finally  distributed  to  the  skin  on  the  out- 
side of  the  thigh.  If  the  external  cutaneous  be  not  found  in  its 
usual  situation,  look  for  it  as  a  distinct  branch  of  the  anterior 
crural,  nearer  the  psoas  muscle. 

The  anterior  crural  (d),  the  largest  and  most  important  branch, 
is  formed  by  the  union  of  the  third  and  fourth  lumbar  nerves, 
receiving  a  small  branch  from  the  second.  It  descends  in  a  groove 
between  the  psoas  and  the  iliacus  behind  the  fascia  iliaca,  supplies 
both  these  muscles  and  a  branch  to  the  femoral  artery,  and  then, 
passing  under  the  crural  arch  to  the  outer  side  of  the  femoral 
artery,  is  finally  distributed  to  the  extensor  muscles  of  the  knee, 
to  the  sartorius  and  pectineus,  and  the  skin  -of  the  thigh  and  leg. 

The  obturator  nerve  (/),  next  in  size  to  the  anterior  crural, 
proceeds  from  the  third  and  fourth  lumbar  nerves,  and  some- 
times from  the  second.  It  descends  through  the  psoas  muscle,  and 
then,  getting  to  its  inner  border,  runs  along  the  brim  of  the 
pelvis  above  its  corresponding  vessels  to  the  obturator  foramen, 
through  the  upper  part  of  which  it  passes  to  the  adductor  muscles 
of  the  thigh. 

The  accessory  obturator  nerve,  by  no  means  a  constant  branch, 
is  derived  from  the  third  and  fourth  lumbar  nerves,  and  sometimes 
from  the  obturator  nerve.  It  runs  down  along  the  inner  border  of 
the  psoas,  passes  in  front  of  the  horizontal  ramus  of  the  os  pubis, 
supplies  the  pectineus,  and  gives  off  a  small  branch  to  the  hip- 
joint,  and  another  to  communicate  with  the  anterior  branch  of  the 
obturator  nerve. 

Postponing  the  minute  anatomy  of  the  abdominal  viscera,  begin 
the  examination  of  the  contents  of  the  pelvis. 


THE   PELVIS   AND   ITS   CONTENTS.  499 


DISSECTION   OF   THE   PELVIC   VISCERA. 

The  functions  of  the  pelvis  are  to  protect  its  own  viscera ;  to 
support  those  of  the  abdomen ;  to  give  attachment  to  the  muscles 
which  steady  the  trunk ;  to  transmit  the  weight  of  the  trunk  to 
the  lower  limbs,  and  to  give  origin  to  the  muscles  which  move 
them.  In  adaptation  to  the'se  functions,  the  form  of  the  pelvis 
is  that  of  an  arch,  with  broadly  expanded  wings  at  the  sides, 
and  projections  in  appropriate  situations  to  increase  the  leverage 
of  the  muscles.  The  sacrum,  impacted  between  the  ilia,  repre- 
sents the  keystone  of  the  arch,  and  is  capable  of  supporting  not 
only  the  trunk,  but  great  burdens  besides.  The  sides  or  pillars 
are  represented  by  the  ilia;  these  transmit  the  weight  to  the 
heads  of  the  thigh-bones,  and  are  thickest  and  strongest  just  in 
that  line,  i.e.  the  brim  of  the  pelvis,  along  which  the  weight  is 
transmitted.  Moreover,  to  effect  the  direct  transmission  of  the 
weight,  the  plane  of  the  arch  is  oblique.  This  obliquity  of  the 
pelvis,  its  hollow  expanded  sides,  its  great  width,  the  position  and 
strength  of  the  tuberosities  of  the  ischia,  are  so  many  proofs  that 
man  is  adapted  to  the  erect  posture. 

The  general  conformation  of  the  pelvis  in  the  female  is  modi- 
fied, so  as  to  be  adapted  to  utero-gestation  and  parturition.  Its 
breadth  and  capacity  are  greater  than  in  the  male.  Its  depth  is 
less.  The  alee  of  the  iliac  bones  are  more  expanded.  The  projec- 
tion of  the  sacrum  is  less  perceptible,  and  consequently  the  brim 
is  more  circular.  The  depth  of  the  symphysis  pubis  is  less,  the 
span  of  the  pubic  arch  is  wider.  The  bones,  too,  are  thinner,  and 
the  muscular  impressions  less  strongly  marked. 

The  cavity  of  the  pelvis  being  curved,  the  axis,  or  a  central 
line  drawn  through  it,  must  be  curved  in  proportion.  For  all 
practical  purposes,  it  is  sufficient  to  remember  that  the  axis  of 
the  pelvis  corresponds  with  a  line  drawn  from  the  anus  to  the 
umbilicus.1 

1  In  a  well-formed  female  the  base  of  the  sacrum  is  3|  inches  higher  than  the 
upper  part  of  the  symphysis  pubis,  and  the  point  of  the  coccyx  is  rather  more  than 

K  x  2 


500 


CONTENTS   OF   THE   MALE   PELVIS. 


CONTENTS  OF  The  male  pelvis  contains  the  last  part  of  the 

THE  MAI^E  intestinal  canal  (named  the  rectum),  the  bladder 

PELVIS-  with  the  prostate  gland  at  its  neck,  and  the  vesi- 

culas  seminales.  If  the  bladder  be  empty,  some  of  the  small 
intestine  will  be  in  the  pelvis ;  not  so  if  the  bladder  be  distended. 
The  relative  positions  of  these  pelvic  viscera  are  as  follows  : — 
most  posteriorly  is  the  rectum,  which  follows  the  curve  of  the 
sacrum  and  coccyx,  and  ends  at  the  anus ;  immediately  in  front  is 
the  oval  hollow  viscus,  the  bladder,  which  alters  in  size  and  posi- 
tion according  to  the  amount  of  urine  it  contains ;  in  front  of  the 
bladder,  surrounding  its  neck,  and  behind  the  os  pubis,  is  the  pro- 
state gland.  Placed  beneath  the  bladder  are  the  vesiculge  seminales, 
and  curving  round  the  sides  of  the  bladder  are  the  vasa  deferentia, 
which  subsequently  lie  beneath  the  base  of  the  bladder.  Passing 
downwards  and  inwards  over  the  brim  of  the  pelvis  are  the  ureters, 
which  likewise  get  beneath  the  fundus  vesicse.  The  bladder  and 
the  rectum  are  partially  invested  with  peritoneum.  Besides  the 
pelvic  viscera  just  enumerated,  there  are  found,  to  the  outer  part 
of  the  pelvic  cavity,  the  internal  iliac  artery  and  its  branches,  and 
the  sacral  plexus  of  nerves,  with  the  obturator  nerve  running- 
forwards  to  the  obturator  foramen.  All  the  pelvic  viscera  are 
more  or  less  invested  by  prolongations  from  the  pelvic  fascia., 
which  constitute  some  of  the  true  ligaments  of  the  bladder ;  also 
a  capsule  for  the  prostate,  and  coverings  for  the  pelvic  muscles. 
The  superior  haemorrhoidal  artery,  the  continuation  of  the  in- 
ferior mesenteric,  passes  down  into  the  pelvis,  and  supplies  the 

half  an  inch  higher  than  the  lower  part  of  the  symphysis.  The  obliquity  of  the 
pelvis  is  greatest  in  early  life.  In  the  foetus,  and  in  young  children,  its  capacity 
is  small,  and  the  viscera,  which  subsequently  belong  to  it,  are  situated  in  the 
abdomen. 

The  relative  diameters  of  the  male  and  the  female  true  pelvis  are  as  follows  : — 


MALE 

FEMALE 

Brim 

Cavity 

Outlet 

Brim 

Cavity 

Outlet 

Transverse 
Oblique       .         .         . 
Antero-posterior 

4 
4 

4^ 

4" 

5* 

4? 

-H-l-p 
W5  «5  >C 

4| 
5 

RECTO-VESICAL   POUCH.  501 

upper  half  of  the  rectum.  Some  of  these  structures  will  now  be 
described,  while  others  can  be  better  dissected  in  the  side  view  of 
the  pelvis. 

COURSE  OF  The  rectum  enters  the  pelvis  on  the  left  side  of 

THE  EECTUM.  the  sacrum,  and,  after  describing  a  curve  corre- 

sponding with  the  concavity  of  the  sacrum,  terminates  at  the  anus. 
In  the  first  part  of  its  course  it  is  loosely  connected  to  the  back  of 
the  pelvis  by  a  peritoneal  fold,  called  the  meso^ectum :  between  the 
layers  of  this  fold,  the  superior  hsemorrhoidal  vessels,  the  continu- 
ation of  the  inferior  mesenteric,  with  nerves  and  lymphatics,  runs 
to  the  bowel. 

The  rectum  does  not  take  this  course  in  all  cases ;  sometimes 
it  makes  one,  or  even  two  lateral  curves.  In  some  rare  cases 
it  enters  the  pelvis  on  the  right  side  instead  of  the  left.  Since 
these  variations  from  the  usual  arrangement  cannot  be  ascertained 
during  life,  they  should  make  us  cautious  in  the  introduction  of 
bougies.1 

EECTO-VESICAL  Whilst  the  parts  are  still  undisturbed,  introduce 
POUCH.  the  finger  into  the  recto-vesical  peritoneal  pouch 

(fig.  116).  This  is  a  cul-de-sac  formed  by  the  peritoneum  in  pass- 
ing from  the  front  of  the  rectum  to  the  lower  and  back  part  of  the 
bladder.  In  the  adult  male,  the  bottom  of  this  pouch  is  about  one 
inch  distant  from  the  base  of  the  prostate  gland  ; 2  therefore  part 
of  the  under  surface  of  the  bladder  is  not  covered  by  peritoneum  ; 
and  since  this  part  is  in  immediate  contact  with  the  rectum,  it 
is  practicable  to  tap  the  distended  bladder  through  the  front 
of  the  bowel  without  injuring  the  peritoneum.  The  operation 
has,  of  late  years,  been  revived,  and  with  great  success.3  It  is 
easily  done,  and  not  attended  with  risk,  provided  all  the  parts 
be  in  their  regular  position.  But  this  is  not  always  the  case.  It 
sometimes  happens  that  the  peritoneal  pouch  comes  down  nearer 
to  the  prostate  than  usual — we  have  seen  it  in  actual  contact 
with  the  gland  ;  so  that,  in  such  a  case,  it  would  be  impossible  to 

*.  *  In  old  age  the  rectum  has  sometimes  a  zigzag  appearance  immediately  above 
the  anus.  These  lateral  inclinations  are  probably  produced  by  the  enormous  dis- 
iensions  to  which  the  bowel  has  been  occasionally  subjected. 

2  The  bottom  of  the  pouch  is  from  three  to  four  inches  distant  from  the  anus. 

3  See  a  paper  in  the  Med.  Chir.  Trans,  vol.  xxxv.  by  Mr.  Cock. 


502 


PELVIC   VISCERA. 


.tap  the  bladder  from  the  rectum  without  going  through  the  peri- 
toneum. In  children  the  peritoneum  comes  down  lower  than  it 
does  in  the  adult,  because  the  bladder  in  the  child  is  not  a  pelvic 
viscus. 

The  recto-vesical  pouch  is  permanent.  But  there  is  another 
peritoneal  pouch  on  the  front  part  of  the  bladder,  which  is  only 
produced  when  the  bladder  is  distended.  To  produce  it,  the 
bladder  should  be  blown  up  through  one  of  the  ureters.  The 


FIG.  116. 


Peritoneum  in  dot- 
ted outline. 


Ureter. 

Vas  deferens. 
Vesicula  seminalis.. 


Symphysis  pubis 

Corpus  cavernosum 
penis 

Glans  penis     .    .    . 

Corpus  spongiosum 
urethras   .    .     .    . 


Bulb  of  corp.  spon- 
giosum .  .  .  . 

Cowper's  gland  with 
duct 

Membranous  part 
of  urethra  sur- 
rounded by  com- 
pressor muscle. 

Prostate  gland    . 


DIAGRAM    OF    THE    RELATIVE    POSITION    OF    THE    PELVI£    VISCERA. 

bladder  soon  fills  the  pelvis,  and  then,  rising  into  the  abdomen,, 
occasions  the  pouch  between  it  and  the  abdominal  wall.  At  first 
the  pouch  is  shallow,  but  it  gradually  deepens  as  the  bladder  rises. 
If  the  bladder  be  distended  half-way  up  to  the  umbilicus,  which  is 
commonly  the  case  when  it  has  to  be  tapped,  we  find  that  the 
bottom  of  the  pouch  would  be  about  two  inches  from  the  symphysis 
pubis  (fig.  116).  Within  this  distance  from  the  symphysis,  the 
bladder  may  be  tapped  in  the  linea  alba,  without  risk  of  wounding 
the  peritoneum.  Thus,  the  surgeon  has  the  choice  of  two  situations 
in  which  he  may  tap  the  bladder — above  the  os  pubis,  or  from  the 


CONTENTS  OF  THE  FEMALE  PELVIS.  503 

rectum.  Which  of  the  two  be  more  appropriate,  must  be  decided 
by  the  circumstances  of  the  case. 

FALSE  LIGAMENTS  The  reflections  of  the  peritoneum  from  the 
OF  THE  BLADDEB.  pelvic  walls  to  the  bladder  constitute  the  false 
ligaments  of  the  bladder,  and  they  can  be  best  examined  before  the 
viscera  are  disturbed,  although  they  will  be  described  when  the 
bladder  itself  is  dissected. 

The  two  posterior  pass  forwards  from  the  sides  of  the  rectum  to 
the  back  of  the  bladder,  forming  the  lateral  boundaries  of  the  deep 
recto-vesical  pouch.  Each  contains  within  its  duplicature  the  ob- 
literated hypogastric  artery,  the  ureter,  together  with  some  vessels 
and  nerves. 

The  two  lateral  pass  inwards  from  the  sides  of  the  pelvis  to  the 
sides  of  the  bladder. 

The  superior  passes  upwards  from  the  summit  of  the  bladder  to 
the  back  of  the  anterior  abdominal  wall,  covering  the  urachus  and 
the  obliterated  hypogastric  arteries. 

CONTENTS  OF  The  relative  positions  of  the  pelvic  viscera  in 

THE  FEMALE  the  female  should  now  be  examined,  leaving  the 

PELVIS.  special  description  till  a  later  stage. 

GENERAL  ^e  uterus  ig  interposed  between  the  bladder  in 

POSITION  OF  THE  front,  and  the  rectum  behind.  From  each  side  of 
UTERUS  AND  ITS  ft  a  broad  fold  of  peritoneum  extends  transversely 
APPENDAGES.  to  ^  gide  of  the  pelvis,  dividing  that  cavity  into 

an  anterior  and  a  posterior  part.  These  folds  are  called  the  broad 
ligaments  of  the  uterus  (fig.  135,  p.  571).  On  the  posterior  surface 
of  the  ligament  are  the  ovaries,  one  on  each  side.  They  are  com- 
pletely covered  by  peritoneum,  and  suspended  to  the  ligament  by 
a  small  peritoneal  fold.  Each  ovary  is  attached  to  the  uterus  by  a 
cord  termed  the  ligament  of  the  ovary.  Along  the  upper  part  of  the 
broad  ligament  we  find  between  its  layers  a  tube  about  four  inches 
long,  called  the  Fallopian  tube,  which  conveys  the  ovum  from  the 
ovary  into  the  uterus.  For  this  purpose,  one  end  of  it  terminates 
in  the  uterus,  while  that  nearer  to  the  ovary  expands  into  a  wide 
mouth,  furnished  with  prehensile  fringes — fimbrice — which,  like  so 
many  tentacles,  grasp  the  ovum  as  soon  as  it  escapes  from  the 
ovary.  One  of  these  fimbriae  is  attached  to  the  ovary.  Lastly,  there 


504 


PELVIC   VISCERA   IN    THE    FEMALE. 


run  up  to  the  ovary,  between  the  layers  of  the  broad  ligament,  the 
ovarian  vessels,  which  arise  from  the  aorta  in  the  lumbar  region, 
like  the  spermatic  arteries  in  the  male,  because  the  ovaries  are 
originally  formed  in  the  loins. 

On  the  anterior  surface  of  the  broad  ligament,  on  either  side 
between  its  layers,  is  the  round  ligament  of  the  uterus.  This  cord 
proceeds  from  the  fundus  of  the  uterus,  anterior  to  the  Fallopian 
tube,  through  the  inguinal  canal,  like  the  spermatic  cord  in  the 

FIG.  117. 


Urethra  surround 
ed  by  its  compres 
sor  muscle  .  . 


Vagina 


Rectum 


Peritoneum      in 

dotted  outline. 


VERTICAL    SECTION    THROUGH    THE    FEMALE    PELVIC    VISCERA. 

male,  and  terminates  in  the  mons  Veneris.  Besides  one  or  two 
small  blood-vessels,  it  contains  muscular  fibres  analogous  to  those 
of  the  uterus  ;  these  increase  very  much  in  pregnancy,  so  that, 
about  the  full  term,  the  cord  becomes  nearly  as  thick  as  the  end  of 
the  little  finger.  In  early  life,  the  round  ligament  receives  a  cover- 
ing from  the  peritoneum,  which  advances  in  a  tubular  form  into 
the  inguinal  canal.  It  corresponds  to  the  processus  vaginalis  of 


DISSECTION    OF   THE    MALE    PERINEUM. 


505 


the  peritoneum  in  the  male.  It  is  called  the  canal  of  Niick,  and  is 
generally  obliterated  in  the  adult.  It  is  sometimes  the  seat  of  an 
inguinal  hernia. 

RELECTIONS  From  the  front  of  the  rectum  the  peritoneum  is 

OF  THE  PERI-  reflected  on  to  a  small  part  of  the  posterior  wall  of 

TONZUM.  the  vagina,  thus  forming  what  is  called  the  recto- 

vaginal  pouch.  From  the  vagina  the  peritoneum  is  continued  over 
the  posterior  surface,  but  only  about  half-way  down  the  front  of 
the  uterus ;  thence  it  is  reflected  over  the  posterior  surface  of  the 
bladder,  on  to  the  wall  of  the  abdomen.  Laterally,  it  is  reflected 
from  the  uterus  to  the  sides  of  the  pelvis,  forming  the  broad  liga- 
ments (p.  571). 

In  cases  of  ascites  the  fluid  might  distend  the  recto-vaginal 
pouch,  and  bulge  into  the  vagina,  so  that  it  would  be  practicable 
to  draw  it  off  through  this  channel. 


FIG.  118. 


DISSECTION   OF   THE   MALE   PERINEUM. 

Before  dissecting  the  perineum,  it  is  expedient  first  to  examine 
the  osseous  and  ligamentous  boundaries  of  the  lower  aperture  of 
the  pelvis.  Looking  at  the  male  pelvis  (with  the  ligaments  pre- 
served), we  observe  that  this  aperture  is 
of  a  lozenge  shape  ;  that  it  is  bounded 
in  front  by  the  pubic  arch  and  the  sub- 
pubic  ligament;  laterally,  anteriorly,  by 
the  rami  of  the  os  pubis  and  ischium,  and 
the  tuberosity  of  the  ischium,  posteriorly, 
by  the  great  sciatic  ligament ;  and  behind, 
by  the  tip  of  the  coccyx. 

This  space,  for  convenience  of  de- 
scription, is  subdivided  into  two  by  a 
line  drawn  from  one  tuber  ischii  to  the 
other.  The  anterior  forms  a  nearly 
equilateral  triangle,  of  which  the  sides  are  from  three  to  three  and 
a  half  inches  long ;  and,  since  it  transmits  the  urethra,  it  is  called 


DIAGRAM      OF      THE      FRAMEWORK 
OF    THE    PERINEUM. 


506  DISSECTION   OF   THE   MALE   PERINEUM. 

the  uretkral  region  of  the  perineum.     The  posterior,  containing  the 
anus,  is  called  the  ischio-rectal  or  anal  region  (fig.  118).1 

The  subject  should  be  placed  in  the  usual  position  for  lithotomy,, 
with  a  block  placed  beneath  the  pelvis.  A  full-sized  staff  should 
now  be  passed  into  the  bladder,  the  rectum  moderately  distended 
with  tow,  and  the  scrotum  raised  by  means  of  hooks.  A  central 
ridge,  named  theraphe,  extends  from  the  anus,  along  the  perineum, 
scrotum,  and  under  surface  of  the  penis.  Between  the  tuberosities 
of  the  ischia  and  the  anus  are  two  depressions,  one  on  each  side, 
marking  the  ischio-rectal  fossce,  which  are  found  immediately  be- 
neath the  skin,  filled  with  more  or  less  fat.  In  the  lateral  opera- 
tion of  lithotomy,  the  incision  should  commence  at  a  point  midway 
between  the  anus  and  the  posterior  fold  of  the  scrotum,  close  to 
the  left  side  of  the  raphe ;  it  should  be  carried  downwards  and 
outwards  to  a  point  midway  between  the  tuber  ischii  and.  the 
anus.  In  the  bilateral  operation,  the  incision  is  semilunar,  the 
horns  being  made  on  either  side  between  the  tuber  ischii  and  the 
anus,  equidistant  from  these  points  respectively  ;  while  the  centre 
of  the  incision  runs  about  three-quarters  of  an  inch  above  the 
anus. 

At  the  anus  the  skin  becomes  finer  and  more 
delicate,  forming  a  gradual  transition  towards 
mucous  membrane :  during  life  it  is  drawn  into  wrinkles  by  the 
permanent  contraction  of  the  cutaneous  sphincter.  Moreover,  the 
skin  at  the  margin  of  the  anus  is  provided  with  numerous  minute 
glands,2  which  secrete  an  unctuous  substance  to  facilitate  the 
passage  of  the  fasces.  When  this  secretion  becomes  defective  or 
vitiated,  the  anal  cutaneous  folds  are  apt  to  become  excoriated, 
chapped,  or  fissured  ;  and  then  defalcation  becomes  very  painful. 
At  the  margin  of  the  anus  a  thin  white  line  can  be  distinguished, 
indicating,  not  only  the  junction  of  the  skin  with  the  mucous  mem- 

1  The  dimensions  of  the  lower  outlet  of  the  pelvis  are  apt  to  vary  in  different 
subjects,  and  the  lithotomist  must  modify  his  incision  accordingly. 

2  These  glands  are  the  analogues  of  the  anal  glands  in  some  animals,  e.g.  the 
dog  and  the  beaver.     They  are  found  not  only  about  the  anus,  but  also  in  the  sub- 
cutaneous tissue  of  the  perineum,  a  fact  for  the  demonstration  of  which  we  are. 
indebted  to  the  late  Professor  Quekett.   They  are  large  enough  to  be  seen  with  the 
naked  eye. 


ISCHIO-RECTAL   FOSSAE.  507 

brane,  but  also  the  linear  interval  between  the  external  and  internal 
sphincters.1 

The  skin  should  be  reflected,  by  making  an  in- 
DISSECTION 

cision  along  the  raphe,  round  the  margin  of  the 

anus  to  the  coccyx.  Two  others  must  be  made  on  each  side  at 
right  angles  to  the  first,  the  one  at  the  upper,  and  the  other  at  the 
lower  end  of  it.  The  skin  of  the  perineum  must  then  be  reflected 

SUBCUTANEOUS  outwards  with  much  care,  otherwise  the  superficial 
TISSUE.  sphincter  ani  may  be  reflected  with  the  skin.  In 

reflecting  the  skin,  notice  the  characters  of  the  subcutaneous  struc- 
ture.2 Its  characters  alter  in  adaptation  to  the  exigencies  of  each 
part.  On  the  scrotum  the  fat  constituent  of  the  tissue  is  entirely 
absent ;  while  the  connective  tissue  element  is  most  abundant,  and 
during  life  elastic  and  contractile.  But,  towards  the  deeper  part 

FAT  IN  ISCHIO-  of  the  anus,  the  fat  accumulates  more  and  more, 
BECTAL  Fossa:.  and  on  either  side  of  the  rectum  it  is  found  in  the 
shape  of  large  masses,  filling  up  what  would  otherwise  be  two  deep 
hollows  in  this  situation — namely,  the  ischio-rectal  fossce.  These 
fossae  are  pyramidal,  with  their  bases  towards  the  skin,  and  their 
apices  at  the  divergence  of  the  obturator  internus  and  levator  ani. 
They  are  about  two  inches  in  depth,  and  much  deeper  posteriorly 
than  in  front.  This  accumulation  of  fat  on  each  side  of  the  anus 
permits  the  easy  distension  and  contraction  of  the  lower  end  of 
the  bowel  during  and  after  the  passage  of  the  fseces.  Over  the 
tuberosities  of  the  ischia  are  large  masses  of  fat,  separated  by 
tough,  fibrous  septa,  passing  from  the  skin  to  the  bone,  so  as  to 
make  an  elastic  padding  to  sit  upon.  Occasionally,  too,  there  are 
one  or  more  large  Inirsce,  interposed  between  this  padding  and  the 
bone. 

So  much  respecting  the  general  characters  of  the  subcutaneous 
tissue  of  the  perineum.  Some  anatomists  describe  it  as  consisting 
of  three,  four,  or  even  more  layers,  but  in  nature  we  do  not  find  it 

1  Hilton,  Lectures  on  Eest  and  Pain,  p.  280. 

2  The  probable  thickness  of  this  subcutaneous  tissue  is  a  point  which  ought  ta 
be  determined  by  the  lithotomist  in  making  his  first  incision.     Its  great  thickness 
in  some  cases  explains  the  depth  to  which  the  surgeon  has  to  cut  in  letting  out  pus 
from  the  ischio-rectal  fossa. 


508    CUTANEOUS  VESSELS  AND  NERVES  OF  THE  PERINEUM. 

so.  It  may,  indeed,  be  divided  into  as  many  layers  as  we  please, 
according  to  our/  skill  in  dissection ;  but  this  only  complicates  what 
is,  in  itself,  simple. 

The  external  sphincter  ani  must  now  be  cleaned, 
care  being  taken  not  to  remove  any  of  its  fibres, 
which  are  intimately  connected  with  the  skin.  Posteriorly,  the 
lower  border  of  the  gluteus  maximus  must  be  displayed,  and  the 
Vessels  and  nerves  crossing  the  perineum,  towards  the  anus,  care- 
fully dissected.1 

EXTERNAL  The  external  sphincter  of  the  anus  is  elliptical, 

SPHINCTER  ANI.  and  is  composed  of  a  thin  layer  of  striped  mus- 
cular tissue  about  an  inch  in  breadth.  It  arises  from  the  tip  of 
the  coccyx  and  the  ano-coccygeal  ligament.  The  muscular  fibres 
surround  the  anus,  and  are  inserted  in  a  pointed  manner  in  the 
tendinous  centre  of  the  perineum,  in  conjunction  with  the  trans- 
versus  perinei,  the  accelerator  urines,  and  the  levator  ani  (p.  510). 
It  is  called  the  external  sphincter,  to  distinguish  it  from  a  deeper 
and  more  powerful  band  of  muscular  fibres  which  surrounds  the 
last  inch  or  more  of  the  rectum,  and  is  situated  next  to  the  mucous 
membrane. 

CUTANEOUS  ^h®  cutaneous  vessels  and  nerves  of  the  peri- 

VESSELS  AND  neum  come  from  the  internal  pudic  artery  and 

NEKVES.  nerve,  and  chiefly  from  that  branch  of  it  called  the 

superficialis  perinei.     This  will  be  traced  presently. 

The  external  or  inferior  hcemorrhoidal  arteries  cross  transversely 
through  the  ischio-rectal  fossa,  from  the  ramus  of  the  ischium  to- 
wards the  anus.  They  come  from  the  pudic  (which  can  be  felt  on 
the  inner  side  of  the  ischium),  and,  running  inwards,  divide  into 
numerous  branches,  which  supply  the  rectum,  levator  ani,  and 
sphincter  ani.  The  nerves  which  accompany  the  arteries  come 
from  the  pudic  nerve,  and  supply  the  sphincter  ani  and  the  skin  of 
the  perineum. 

The  fourth  sacral  nerve  emerges  through  the  coccygeus  close  to 
the  tip  of  the  coccyx,  and,  through  its  hcemorrhoidal  or  perineal 

1  Radiating  outwards  from  the  margin  of  the  anus  is  a  thin  stratum  of 
involuntary  muscular  fibres,  called  the  corrugator  cutis  ani,  which  by  its  action 
produces  the  radiating  ridges  of  skin  from  the  anus. 


SUPERFICIAL    FASCIA    OF   THE    PERINEUM.  509 

branch,  supplies  the  external  sphincter  and  the  skin  of  the  perineum 
between  the  coccyx  and  the  anus. 

The  inferior  pudendal  nerve  comes  through  the  muscular  fascia 
of  the  thigh,  a  little  above  the  tuber  ischii,  and  ascends,  dividing 
into  filaments,  which  supply  the  front  and  outer  part  of  the  scrotum 
and  perineum.  It  is  a  branch  of  the  lesser  sciatic  nerve,  and  com- 
municates in  front  with  the  posterior  branch  of  the  superficial 
perineal  nerve. 

SUPERFICIAL  The    subcutaneous    fascia  of  the   perineum   is 

FASCIA  OP  THE  composed  of  a  superficial  and  a  deep  layer.     The 

superficial  layer  contains  more  or  less  fat,  and  is 
continuous  with  that  of  the  scrotum,  the  thighs,  and  the  posterior 
part  of  the  perineum.  The  deeper  layer  is  a  stratum  of  consider- 
able strength,  and  is  best  demonstrated  by  blowing  air  beneath  it 
with  a  blow-pipe ;  its  connections  are  as  follows  :— It  is  attached 
on  each  side  to  the  anterior  lip  of  the  ramus  of  the  os  pubis  and 
ischium  superficial  to  the  crus  penis ;  traced  forwards,  it  is 
directly  continuous  with  the  tunica  dartos  of  ,the  scrotum ;  traced 
backwards,  at  the  base  of  the  urethral  triangle,  it  is  reflected 
beneath  the  transversus  perinei  muscle,  and  joins  the  deep 
perineal  fascia  or  triangular  ligament.  These  connections  explain 
why  urine,  effused  into  the  perineum,  does  not  make  its  way 
into  the  ischio-rectal  fossae,  or  down  the  thighs,  but  passes 
readily  forwards  into  the  connective  tissue  of  the  scrotum,  penis, 
and  groins. 

Remove  the  fascia  to  see  the  muscles  which 
cover  the  bulb  of  the  urethra  and  the  crura  of 
the  penis.  The  bulb  of  the  urethra  lies  in  the  middle  of  the 
perineum,  and  is  covered  by  a  strong  muscle,  called  accelerator 
urinse.  The  crura  penis  are  attached,  one  to  each  side  of  the  pubic 
arch,  and  are  covered  each  by  a  muscle,  called  erector  penis.  A 
narrow  slip  of  muscle,  called  transversus  perinei,  extends  on  either 
side  from  the  tuber  ischii  to  the  tendinmis  centre  of  the  perineum. 
This  point  is  about  one  inch  and  a  quarter  in  front  of  the  anus, 
and  serves  for  the  attachment  of  muscular  fibres  from  all  quarters 
of  the  perineum. 

Thus  the  muscles  of  the  perineum  describe  on  each  side   a 


510 


SUPERFICIAL   FERINE  AL   VESSELS   AND   NERVES. 


triangle,  of  which  the  sides  are  formed  by  the  accelerator  u  rinse 
and  the  crus  penis  respectively,  and  the  base  by  the  transversus 
perinei.  Across  this  triangle  run  up  from  base  to  apex  the  super- 
ficial perineal  vessels  and  nerves.  External  to  the  ramus  of  the 
ischium  is  seen  the  inferior  pudenda!  nerve,  a  branch  of  the  lesser 
sciatic. 

FIG.  119. 


Triangular  liga- 
ment .  .]  I.  . 

Tendinous  centre 
of  the  perineum 

Transversus  peri- 
nei   


Ischio-rectal 
fossa  .    . 


Superficialis 
-      perinei  a. 
7'  External    hie- 
,'/     morrhoid 
u.  and  n. 


MUSCLES,    WITH    SUPERFICIAL    VESSELS    AND    NERVES,    OF    THE    PERINEUM. 


SUPERFICIAL  superficial  perinea!  artery  lies  beneath  the 

PERINEAL  VESSELS     deep  layer  of  the  superficial  perineal  fascia,  and 
AND  NERVES.  comes  from  the  internal  pudic  as  it  runs  up  the 


ACCELERATOR   URIN.E.  511 

inner  side  of  the  tuber  ischii.  Though  the  main  trunk  cannot  be 
seen,  it  can  be  easily  felt  by  pressing  the  finger  against  the  bone. 
The  artery  comes  into  view  a  little  above  the  level  of  the  anus, 
passes  up  usually  in  front  of  the  transversus  perinei  muscle,  and 
gets  to  the  perineal  triangle  lying  to  the  inner  side  of  the  erector 
penis.  It  distributes  branches  to  all  the  muscles,  and  is  finally 
lost  on  the  scrotum.  The  only  named  branch  is  called  transversalis 
perinei  (fig.  119).  This  is  given  off  near  the  base  of  the  triangle, 
and  runs  transversely  inwards  with  the  transversus  perinei  muscle 
towards  the  central  tendon  of  the  perineum,  where  it  anastomoses 
with  its  fellow.  It  is  necessarily  divided  in  the  first  incision  in 
lithotomy,  and  deserves  attention,  because  it  is  sometimes  of  con- 
siderable size. 

The  artery  is  accompanied  by  two  veins,  which  are  frequently 
dilated  and  tortuous^  especially  in  diseased  conditions  of  the 
scrotum. 

The  nerves,  two  in  number,  are  derived  from  the  internal  pudic, 
follow  the  course  of  their  corresponding  arteries,  and  give  off 
similar  branches.  They  not  only  supply  the  skin  of  the  perineum 
and  scrotum,  but  each  of  the  perineal  muscles. 

ACCELERATOR  This  muscle  embraces  the  bulb  of  the  urethra, 

UKIN^:.  and  is  composed  of  two  lateral  symmetrical  halves. 

It  arises  from  a  fibrous  median  raphe  beneath  the  bulb,  and  from 
the  tendinous  centre  of  the  perineum.  Starting  from  this  origin, 
the  fibres  diverge,  and  are  inserted  as  follows  : — The  upper  ones 
proceed  on  either  side  round  the  corpus  cavernosum  penis,  like  the 
branches  of  the  letter  V,  and  are  fixed  on  its  dorsal  surface,  in 
front  of  the  erector  penis,  and  expanding  also  into  a  broad  apo- 
neurosis,  which  covers  the  dorsal  vessels  of  the  penis ;  the  middle 
completely  embrace  the  bulb  and  adjacent  part  of  the  corpus 
spongiosuiii  like  a  ring,  and  meet  in  an  aponeurosis  on  the  upper 
surface  of  the  urethra ;  the  lower  are  fixed  to  the  anterior  surface 
of  the  deep  perineal  fascia,  often  called  the  triangular  ligament 
(fig.  120).' 

Thus,  the  entire  muscle  acts  as  a  powerful  compressor  of  the 

1  This  muscle  is  called  also  the  ejaculator  urince  or  the  bulbo-cavernosus. 


512 


MUSCLES   OF   THE    PEKINEUM. 


bulb,  and  expels  the  last  drops  of  urine  from  this  part  of  the 
urethra.1  By  dividing  the  muscle  along  the  middle  line  and 
turning  back  each  half,  its  insertion,  as  above  described,  can  be 
clearly  made  out. 

ERECTOR  This  muscle  is  moulded  upon  the  crus  of  the 

PENIS.  penis.     It  arises  by  musculo-tendinous  fibres  from 

the  inner  surface  of  the  tuber  ischii,  from  the  crus  itself,  and  from 
the  ramus  of  the  os  pubis ;  the  fibres  ascend,  completely  covering 
the  crus,  and  terminate  on  a  strong  aponeurosis,  which  is  inserted 

FIG.  120. 


Corpus  cavernosum 


Corpus  spongi 


Upper  fibres 


Middle  fibres 


Lower  fibres 

Tendinous   centre  of  peri- 
neum      


COWPERS 
TRIANGULAR 

L'CAMENT 


DIAGRAM   TO   SHOW   THE    ACCELERATOR   URIN/E    IN   PROFILE. 

into  the  external  and  inferior  aspect  of  the  crus  penis.  The  action 
of  this  muscle  is  to  compress  the  root  of  the  penis,  and  so,  by  pre- 
venting the  return  of  the  venous  blood,  contributes  to  the  erection 
of  the  organ.2 

THANSVERSUS  This  muscle  is  of  insignificant  size,  and  some- 

PERINEI.  times  absent.     It  arises  from  the  inner  aspect  of 

the  tuber  ischii,  and  proceeds  forwards  and  inwards  towards  the 

1  The  oniddle  fibres  assist  in  the  erection  of  the  corpus  spongiosum,  and  the 
upper  fibres  in  that  of  the  penis  :  the  former  by  compressing  the  bulb,  the  latter  by 
compressing  the  dorsal  vein. 

2  This  muscle  is  sometimes  called  the  ischio-cavernosus. 


MUSCLES   OF   THE   PERINEUM. 


513 


central  point  of  the  perineum,  where  it  is  blended  with  the  muscle 
of  the  opposite  side,  with  the  fibres  of  the  accelerator  urinaD  in 
front,  and  with  the  external  sphincter  behind.  This  muscle  with 
its  artery  is  divided  in  lithotomy. 


Cms  penis     .    .    . 

Cms  penis  with 
its  artery  cut 
through  .  .  , 


Ramus.  of  the   os 
pubis     .    .    .    . 


Artery  of  the  bulb 
Co wper's  gland.  . 
Pudic  artery  .  .  . 


Tuber  ischii  .    .    . 


PIG.  121. 


DIAGRAM    TO    SHOW   THE    TRIANGULAR   LIGAMENT    OF   THE    URETHRA 
OR   DEEP    PEKINEAL   FASCIA. 

The  deep  transversus  perinei  is  a  small  muscle  occasionally 
present ;  it  arises  more  deeply  from  the  pubic  arch  than  the  super- 
ficial muscle,  and  passes  inwards  behind  the  bulb  to  the  central 
tendon. 

L  L 


514 


TRIANGULAR   LIGAMENT. 


The  next  stage  of  the  dissection  consists  in  reflecting  and 
removing  the  accelerator  urinas  from  the  bulb  of  the  urethra,  the 
erectores  penis  with  the  crura  penis  from  the  rami  of  the  os  pubis 


PIG.  122. 


Compressor  urethra 
Membranous  part 
of  the  urethra 
surrounded  by  its 
compressor  muscle. 
Prostate  gland  .  . 


Anterior    fibres 
the  levator  aui 


of 


DIAGRAM   OF   THE   PARTS   BEHIND   THE   ANTERIOR   LAYER   OF   THE    TRIANGULAR 
LIGAMENT    OF    THE    URETHRA. 

(The  anterior  fibres  of  the  levator  ani  are  hooked  down  to  show  part  of  the 
prostate  ;  the  rest  is  tracked  by  a  dotted  line.) 


and  ischium,  and  the  transversi  perinei  muscles.     This  done,  the 
triangular  ligament  or  deep  perinecd  fascia  is  fairly  exposed. 


TRIANGULAR  LIGAMENT.  515 

TRIANGULAR  Understand  that  the  triangular  ligament  of  the 

LIGAMENT  OF  THE      urethra  and  the  deep  perineal  fascia  are  synony- 
URETHRA.  mous  terms. 

The  triangular  ligament,  shown  in  fig.  122,  is  a  strong  fibrous 
membrane  stretched  across  the  pubic  arch.  It  is  about  an  inch 
and  a  half  in  depth,  with  the  base  directed  backwards.  It  con- 
sists of  two  layers — an  anterior  and  a  posterior.  The  anterior 
layer  is  firmly  attached  on  each  side  to  the  posterior  lip  of  the  rami 
of  the  os  pubis  and  ischium,  beneath  the  crus  penis  ;  superiorly — 
i.e.,  towards  the  symphysis  of  the  os  pubis — it  is  connected  with 
the  subpubic  ligament ;  inferiorly,  it  does  not  present  a  free 
border,  but  is  connected  to  the  tendinous  centre  of  the  perineum, 
and  is  continuous  with  the  deep  layer  of  the  superficial  perineal 
fascia  which  curves  backwards  under  the  transversus  perinei  muscle, 
and  with  the  ischio-rectal  or  anal  fascia  (p.  509). 

The  anterior  layer  of  the  triangular  ligament  is  perforated 
about  one  inch  below  the  symphysis  pubis  for  the  membranous 
part  of  the  urethra.  The  aperture  through  which  the  urethra 
passes  does  not  present  a  distinct  edge,  because  the  ligament  is 
prolonged  forwards  over  the  bulb,  and  serves  to  keep  it  in  position. 
It  also  presents  apertures  for  the  transmission  of  the  dorsal  vein, 
and  outside  this  for  the  pudic  arteries  and  nerves. 

The  posterior  layer  cannot  at  present  be  seen.  It  belongs, 
strictly  speaking,  to  the  obturator  prolongation  of  the  pelvic  fascia, 
and  slopes  somewhat  backwards  from  the  anterior  layer  so  as  to 
leave  an  interval  between  them,  in  which  are  found  structures  which 
will  be  presently  described. 

POINTS  OF  SUR-          The    triangular    ligament    is    very    important 
GICAL  INTEREST.        surgically  for  these  reasons  : — 

1.  Here  we  meet  with  difficulty  in  introducing   a   catheter, 
unless  we  can  hit  off  the  right  track  through  the  ligament.     The 
soft  and  spongy  tissue  of  the  bulbous  part  of  the  urethra  in  front 
of  the  ligament  readily  gives  way  if  force  be  used,  and  a  false 
passage  results. 

2.  By  elongating  the  penis,  we  are  much  more  likely  to  hit  off 
the  proper  opening  through  the  ligament. 

3.  When,  in  retention  of  urine,  the  urethra  gives  way  anterior 

L  L   2 


516  PARTS   DIVIDED   IN   LATERAL    LITHOTOMY. 

to  this  ligament,  it  is  this  which  prevents  the  urine  from  travelling 
into  the  pelvis.  Its  connection  with  the  superficial  permeal  fascia 
prevents  the  urine  from  getting  into  the  ischio-rectal  fossae :  nor 
can  the  urine  make  its  way  into  the  thighs.  The  only  outlet  for 
it  is  into  the  connective  tissue  of  the  scrotum  and  penis. 

4.  When   suppuration  or  extravasation  of  urine  takes  place 
behind  the  ligament,  the  pus  is  pent  up  and  should  be  speedily  let 
out ;  if  not,  it  may  find  its  way  into  the  connective  tissue  of  the 
pelvis,  and  may  burst  into  the  urethra  or  the  rectum. 

5.  The  ligament  is  partially  cut  through  in  lithotomy. 

PARTS  DIVIDED  The   parts  divided  in  the  lateral  operation  of 

IN  LATERAL  lithotomy  are  :  the  skin,  the  superficial  fascia,  the 

LITHOTOMY.  ^  transverse  perineal  muscle,  vessels  and  nerve,  the 

inferior  haemorrljioidal  vessels  and  nerves,  the  inferior  fibres  of  the 
accelerator  urinse,  the  anterior  fibres  of  the  levator  ani,  the  tri- 
angular ligament  (anterior  layer),  the  compressor  urethras,  the 
membranous  and  prostatic  parts  of  the  urethra,  and  a  small  portion 
of  the  prostate. 

PARTS  TO  BE  The   incision    in  lateral  lithotomy  should  not 

AVOIDED.  be  made  too  far  forwards,  for  fear  of  wounding 

the  artery  of  the  bulb ;  nor  too  far  inwards,  for  fear  of  injuring 
the  rectum ;  nor  too  far  outwards,  for  fear  of  cutting  the  pudic 
artery. 

The   anterior  layer  of  the  triangular  ligament 
BETWEEN  THE  must  now  be  cut  away  to  see  what  lies  between 

LAYERS  OF  THE  its  two  layers.  These  parts  are  shown  in  fig.  122  ; 
TRIANGULAR  namely :  1 ,  the  membranous  part  of  the  urethra, 

surrounded  by,  2,  the  compressor  urethras  muscle ; 
3,  Cowper's  glands  and  their  ducts ;  4,  the  pudic  artery  and  its 
branch,  the  artery  of  the  bulb ;  the  artery  of  the  crus  and  the 
dorsal  artery  of  the  penis  being  given  off  in  front  of  the  anterior 
layer ;  5,  the  pudic  nerve  and  its  branches ;  6,  the  dorsal  vein  of 
the  penis  ;  7,  the  subpubic  ligament. 

To  obtain  the  best  perineal  view  of  the  com- 
pressor urethrae  muscle,  cut  through  the  spongy 
part  of  the  urethra  about  three  inches  above  the  end  of  the  bulb, 
and  dissect  it  from  the  corpus  cavernosum.    Thus,  the  upper  fibres 


PUDIC   ARTERY   AND   ITS   BRANCHES.  517 

of  the  constrictor  will  be  exposed ;  to  see  the  lower,  it  is  only 
necessary  to  raise  the  bulb.  The  most  perfect  view,  however,  of 
the  muscle  is  obtained  by  making  a  transverse  section  through  the 
rami  of  the  ossa  pubis,  so  as  to  get  at  the  muscle  from  above,  as 
shown  in  fig.  123. 

COMPRESSOR  OB  This  muscle  consists  of  transverse  fibres  which 
CONSTRICTOR  surround  and  support  the  whole  length  of  the 

URETHRA.  membranous  portion  of  the  urethra  in  its  passage 

between  the  two  layers  of  the  triangular  ligament.  It  arises  from 
the  ramus  of  the  os  pubis  on  either  side  for  about  half  an  inch ; 
from  thence  its  fibres  pass,  some  above,  some  below  the  urethra, 
along  the  whole  length  of  its  membranous  part.  It  forms  a  com- 
plete muscular  covering  for  the  urethra  between  the  prostate  and 
the  bulb.  It  is  chiefly  through  its  agency  that  we  retain  the 
urine.  This  muscle  is  the  chief  cause  of  spasmodic  stricture  of  the 
urethra.1  Besides  this  muscle,  the  membranous  portion  of  the 
urethra  is  surrounded  by  involuntary  circular  muscular  fibres, 
placed  beneath  the  compressor  urethras,  and  continuous  with  the 
muscular  fibres  of  the  bladder. 

COWPER'S  These  small  glands  are  situated,  one  on  either 

GLANDS.  side,  immediately  behind  the  bulb  between  the 

two  layers  of  the  triangular  ligament,  in  the  substance  of  the 
compressor  urethrae.  Their  size  is  about  that  of  a  pea,  but  it 
varies  in  different  individuals.  They  are  compound  racemose 
glands,  consisting  of  several  lobules  firmly  connected  together  by 
cellular  and  some  muscular  tissue.  From  each  a  slender  duct  runs 
forwards,  and,  after  a  course  of  about  one  inch,  opens  obliquely 
into  the  floor  of  the  bulbous  part  of  the  urethra  (fig.  120).  They 
furnish  a  secretion  accessory  to  generation. 

PUDIC  ARTERY  The  internal  pudic  artery  is  a  branch  of  the 

AND  ITS  anterior  division  of  the  internal  iliac.  It  leaves 

BRANCHES.  ^e  peivjs  through  the  great  sciatic  foramen  be- 

tween the  pyriformis  and  coccygeus  muscles,  above  the  sciatic 
artery,  winds  round  the  spine  of  the  ischium,  re-enters  the  pelvis 

1  The  compressor  urethrse  was  first  accurately  described  and  delineated  by 
Santorini  (septemdec.  tabulas),  and  afterwards  by  Muller  in  his  monograph  (Ueber 
die  organ.  Nerv.  der  mannlich.  Geschlechtsorgane). 


518 


INTERNAL  PUDIC  ARTERY. 


through  the  lesser  sciatic  foramen,  and  then  runs  along  the  inner 
side  of  the  tuber  ischii,  between  the  layers  of  the  obturator  fascia, 
up  towards  the  pubic  arch.  About  an  inch  and  a  half  above  the 
tuber  ischii,  the  trunk  of  the  pudic  artery  can  be  felt ;  but  we 


Catheter    .    .    .    . 


Dorsal  nerve  of  the 
penis 

Dorsal  artery  of 
tlie  pnnis  .  .  . 

Dorsal  vein  of  the 
penis 


Anterior  layer  of 
triangular  liga- 
ment  

Ramus  of  os  pnbis 
cut  through  .  . 

Posterior  layer  of 
triangular  liga- 
ment :  part  of 
the  pelvic  fascia. 


FIG.  123. 


DIAGRAM   OF   THE   RELATIONS   OF   THE    COMPRESSOR   URETHRA    SEEN   FROM   ABOVE. 

cannot  see  it,  nor  draw  it  out,  for  it  is  securely  lodged  in  a  fibrous 
canal  formed  by  the  obturator  fascia.  It  subsequently  pierces  the 
posterior  layer  of  the  triangular  ligament,  runs  along  the  inner 


INTERNAL  PUDIC  ARTERY.  519 

margin  of  the  ramus  of  the  os  pubis,  and  lastly,  piercing  the 
anterior  layer  of  the  triangular  ligament,  it  divides  into  the  artery 
of  the  corpus  cavernosum  and  the  dorsal  artery  of  the  penis.  In 
the  present  dissection  we  find  the  artery  between  the  two  layers 
of  the  triangular  ligament,  where  it  gives  off  the  artery  of  the 
bulb  of  the  urethra,  and  then  pierces  the  triangular  ligament 
(fig.  121). 

Taken  in  order,  the  branches  of  the  pudic  artery  as  seen  in  this 
dissection  are : — 

a.  The   external  hwmorrhoidal    the   superficial  perineal,    and  the 
transverse  perineal  branches  have  already  been  described  (pp.  508,  510). 

b.  The  artery  of  the  bulb  is  of  considerable  size,  and  passes  trans- 
versely inwards  between  the  two  layers  of  the  triangular  ligament ; 
it   runs  inwards   through  the  substance  of  the   compressor  urethras, 
and  before  it  enters  the  bulb  divides  into  two  or  three  branches.     It 
also  sends  downwards  a  small  branch  to  Cowper's  gland.     From  the 
direction  of  this  artery  it  will  at  once  strike  the  attention  that  there  is 
great  risk  of  dividing  it  in  lithotomy.     If  the  artery  run  along  its  usual 
level,  and  the  incision  be  not  made  too  high  in  the  perineum,  then  indeed 
it  is  out  of  the  way  of  harm.     But,  supposing  the  reverse,  the  vessel 
must  be  divided.     This  deviation  from  the  normal  distribution  is  met 
with   about   once   in  twenty  subjects,  and  there  is  no  possibility  of 
ascertaining  this  anomaly  beforehand. 

c.  The  artery  of  the  corpus  cavernosum,  one  of  the  terminal  branches, 
ascends  for  a  short  distance  near  the  pubic  arch,  and  soon  enters  the 
crus,  running  forwards  in  its  cavernous  structure  by  the  side  of  the 
septum  pectiniforme. 

d.  To  see  the  dorsal  artery  of  the  penis,  the  crus  should  be  dissected 
from  its  attachment  to  the  symphysis  pubis.     The  artery  pierces  the 
suspensory  ligament,  and  can  be  traced  upon  the  clorsurn  of  the  penis 
down  to  the  glans.     It  forms  a  complete  arterial  circle  with  its  fellow 
round   the  corona   glandis,    and   gives  numerous  ramifications  to  the 
papillae  on  the  surface. 

The  veins  corresponding  with  the  branches  of  the  pudic  artery 
terminate  in  the  pudic  vein,  with  the  exception  of  the  dorsal  vein 
of  the  penis.  This  vein  is  of  large  size  and  results  from  the  union 
of  two  small  veins  in  front  of  the  dorsum  of  the  penis  which  receive 
the  blood  from  the  glans,  the  corpus  spongiosum,  and  the  prepuce. 


520  ISCHIO-RECTAL   FOSSA. 

The  vein  runs  along  the  middle  of  the  dorsum,  pierces,  first,  the 
suspensory  ligament,  and  then  the  triangular  ligament  under  the 
symphysis,  and  divides  into  two  branches  which  open  into  the 
prostatic  plexus. 

The  pudic  nerve  comes  from  the  lower  part  of 
PUDIC  NERVE.  .  ,  . 

the  sacral   plexus,  and  corresponds,   both    in  its 

course  and  branches,  with  the  artery.  It  gives  off,  close  to  its 
origin,  (a)  the  external  or  inferior  hcemorrhoidal,  which  communi- 
cate in  front  with  the  superficial  perineal  and  inferior  pudendal 
nerves  ;  (£>)  the  perineal  which  accompanies  the  superficial  perineal 
artery,  and  divides  into  a  posterior  and  an  anterior  branch  ;  the 
former  runs  to  the  front  of  the;  ischio-rectal  fossa,  distributing 
branches  to  the  sphincter  and  tjae  skin  in  front  of  the  anus ;  the 
latter  lies  in  front  of  the  preceding,  and  supplies  the  scrotum  and 
under  aspect  of  the  penis ;  both  communicate  with  each  other  and 
with  the  inferior  pudendal  nerve ;  (c)  muscular  lyranclies  to  the 
transversus  perinei,  the  accelerator  urines,  the  erector  penis,  and  the 
compressor  urethrse  ;  (d)  the  dorsal  nerve,  which  is  the  main  trunk 
of  the  nerve,  runs  with  the  pudic  artery,  and  with  it  pierces  the 
posterior,  and  then  the  anterior  layer  of  the  triangular  ligament ; 
then  perforating  the  suspensory  ligament  of  the  penis,  it  ac- 
companies the  dorsal  artery  on  its  outer  side,  along  the  dorsum  of 
the  penis  to  the  glans.  In  its  passage  it  supplies  the  integuments 
of  the  penis,  and  sends  off  one  or  two  branches  into  the  corpus 
cavernosum.  This  part  of  the  penis  also  receives  filaments  from 
the  sympathetic  system. 

ISCHIO-BECTAL  This  is  the  deep  hollow,  on  each  side,  between 

FOSSA.  the  anus  and  the  tuber  ischii.     When  all  the  fat 

is  removed  from  it,  observe  that  it  is  lined  on  all  sides  by  fascia. 
Introduce  the  finger  into  it  to  form  a  correct  idea  of  its  extent  and 
boundaries.  Externally,  it  is  bounded  by  the  tuber  ischii  and  the 
fascia  covering  the  obturator  internus  muscle ;  internally,  by  the 
rectum,  levator  ani  and  coccygeus ;  posteriorly,  by  the  gluteus 
maximus ;  anteriorly,  by  the  transversus  perinei.  The  fossa  is 
crossed  by  the  external  haamorrhoidal  vessels  and  nerves. 

These  deep  spaces  on  each  side  of  the  rectum  explain  the  great 
size  which  abscesses  in  this  situation  may  attain.     The  matter  can 


DISSECTION   OF   THE   FEMALE   PEEINEUM.  521 

be  felt  only  through  the  rectum.  Nothing  can  be  seen  outside. 
Perhaps  nothing  more  than  a  little  hardness  can  be  felt  by  the  side 
of  the  anus.  These  abscesses  should  be  opened  early ;  else  they 
form  a  large  cavity,  and  may  burst  into  the  rectum,  and  result  in 
a  fistula. 


DISSECTION  OF  THE  FEMALE  PEKINEUM. 

The  pudenda  in  the  female  consist  of  folds  of  the  integument, 
called  the  labia.  Between  these  is  a  longitudinal  fissure  which 
leads  to  the  orifices  of  the  urinary  and  genital  canals. 

The  pubic  region  is  generally  surmounted  by  an 
LABIA  MAJOEA.  *  °    „        %    ,      J         ^         .         *., 

accumulation  ot   tat,  called  mons    venens,  which 

is  covered  with  hair.  From  this,  two  thick  folds  of  skin  descend, 
one  on  either  side,  constituting  the  labia  majora,  and  gradually 
diminish  in  thickness  towards  the  perineum.  Their  junction, 
about  an  inch  above  the  anus,  is  called  the  posterior  commissure, 
orfrcenulum  labiorum,  within  which  is  a  transverse  crescentic  fold, 
the  fourclietie :  it  is  generally  torn  in  the  first  labour.  Between 
the  fourchette  and  the  posterior  commissure  is  an  oval  depression, 
called  the  fossa  navicularis.  The  inner  layer  of  the  skin  of  the 
labium  is  thinner,  softer,  and  more  like  mucous  membrane  than 
the  outer ;  for  this  reason,  whenever  pus  forms  in  the  labium,  the 
abscess  bursts  on  the  inner  side.  Where  the  labia  are  in  contact, 
they  are  provided  with  small  sebaceous  glands,  of  which  the  minute 
ducts  are  observable  on  the  surface.  They  are  the  analogues  of 
the  scrotum  in  the  male,  and  occasionally  contain  extruded  ovaries, 
forming  a  hernia  of  the  ovary.1 

In  form  and  structure  the  clitoris  resembles  the 
penis  on  a  diminutive  scale,  being  about  an  inch 
and  a  half  long.  It  has,  however,  no  corpus  spongiosum,  or 
urethra.  Like  the  penis,  it  is  attached  to  the  sides  of  the  pubic 
arch  by  two  crura  (fig.  124,  p.  524),  each  of  which  is  grasped  by 
its  special  erector  ditoridis.  The  crura  are  continued  forward  like 

1  See  paper  on  '  Hernia  of  the  Ovary,'  St.  Bartholomew's  Hospital  Reports, 
vol.  xviii. 


522  DISSECTION   OF  THE   FEMALE   PERINEUM. 

the  corpora  cavernosa  of  the  male,  and  unite  to  form  the  body  of 
the  organ,  which  is  surmounted  by  a  small  ylans.  It  has  also, 
like  the  penis,  a  suspensory  ligament.  The  glans  is  provided  with 
extremely  sensitive  papillee,  and  covered  by  a  little  prepuce.  Its 
dorsal  arteries  and  nerves  are  large  in  proportion  to  its  size,  and 
have  precisely  the  same  course  and  distribution  as  in  the  penis. 
Its  internal  structure  consists  of  a  plexus  of  blood-vessels,  which 
freely  communicate  with  those  of  the  labia  minora ;  for  one  cannot 
be  injected  without  the.  other. 

LABIA  MINORA  By  separating  the  external  labia,  two  small  and 

OK  NYMPHS.  thin  folds  of  mucous  membrane  about  an  inch  and 

a  half  in  length,  are  exposed,  x^one  on  either  side,  termed  labia 
minora.  These  folds  converge  anteriorly,  and  form  a  covering  for 
the  clitoris,  called  preputium  clitoridis ;  posteriorly,  they  are  gradu- 
ally lost  on  the  inside  of  the  labia  majora.  They,  unlike  the  labia 
majora,  do  not  contain  fat,  but  are  composed  of  minute  veins. 
Between  the  nymphse  and  about  the  clitoris  are  a  number  of  seba- 
ceous glands. 

Between  the  labia  minora,  and  below  the  clitoris,  is  an  angular 
depression  called  the  vestibule,  at  the  back  of  which  is  the  meat-its 
urinarius.  Immediately  below  this  is  the  vagina,  of  which  the 
orifice  is  partially  closed  in  the  virgin  by  a  thin  fold  of  mucous 
membrane  called  the  hymen. 

The  hymen  is  a  thin  fold  of  mucous  membrane 
which,  in  the  virgin,  extends  across  the  lower  part 
of  the  entrance  of  the  vagina,  about  half  an  inch  behind  the  four- 
chette.  In  most  instances  its  form  is  crescent-shaped,  with  the 
concavity  upwards.  There  are  several  varieties  of  hymen :  some- 
times there  are  two  folds,  one  on  either  side,  so  as  to  make  the 
entrance  of  the  vagina  a  mere  vertical  fissure ; !  or  there  may  be  a 
septum  perforated  by  several  openings,  hymen  onbriformis,  or  by 
one  only,  hymen  circularis.  Again,  there  may  be  no  opening  at 
all  in  it,  and  then  it  is  called  hymen  imperforatus.  Under  this 
last  condition  no  inconvenience  arises  till  puberty.  The  menstrual 
discharge  must  then  necessarily  accumulate  in  the  vagina :  indeed, 

1  Such  a  one  may  be  seen  in  the  Museum  of  the  College,  Phys.  Series  No. 
2843. 


DISSECTION   OF   THE   FEMALE   PERINEUM.  523 

the  uterus  itself  may  become  distended  by  it  to  such  an  extent  as 
even  to  simulate  pregnancy.1 

When  the  hymen  is  ruptured,  it  shrivels  into  a  few  irregular 
eminences,  called  carunculce  myrtiformes. 

The  presence  of  the  hymen  is  not  necessarily  a  proof  of  vir- 
ginity, nor  does  its  absence  imply  the  loss  of  it.  Cases  are  re- 
lated by  writers  on  midwifery  in  which  a  division  of  the  hymen 
was  requisite  to  facilitate  parturition.  In  Meckel's  Museum,  at 
Halle,  are  preserved  the  external  organs  of  a  female  in  whom  the 
hymen  is  perfect  even  after  the  birth  of  a  seven-months'  child. 

BARTHOLIX'S  Between  the  orifice  of  the  vagina  and  the  erector 

OB  DUVEBNEY'S  clitoridis  is  imbedded  in  the  loose  tissue  on  either 
GLANDS.  s[^e  a  smau  gland,2  which  corresponds  to  Cowper's 

gland  in  the  male.  Each  is  about  half  an  inch  in  length.  Its  long 
slender  duct  runs  forwards  and  opens  on  the  inner  side  of  the 
nympha  external  to  the  hymen.  In  cases  of  virulent  gonorrhoea 
these  glands  are  apt  to  become  diseased,  and  give  rise  to  the 
formation  of  an  abscess  in  the  labium,  very  difficult  to  heal. 

A  smooth  channel,  called  the  vestibule,  three- 
quarters  of  an  inch  in  length,  leads  from  the 
clitoris  down  to  the  orifice  of  the  urethra.  This  orifice,  meatus 
urinarius,  is  not  a  perpendicular  fissure  like  that  of  the  penis, 
but  rounded  and  puckered,  and  during  life  has  a  peculiar  dimple- 
like  feel,  which  assists  us  in  finding  it  when  we  pass  a  catheter. 
You  should  practise  the  introduction  of  the  catheter  in  the  dead 
subject,  for  the  operation  is  not  so  easy  as  might  at  first  be  ima- 
gined, provided  the  parts  are  not  exposed.  The  point  of  the  fore- 
finger of  the  left  hand  should  be  placed  at  the  entrance  of  the 
vagina,  and  the  meatus  felt  for ;  when  the  catheter,  guided  by  the 
finger,  slips,  after  a  little  manoeuvring,  into  the  urethra.  The 
canal  is  about  one  inch  and  a  half  in  length,  and  runs  along 
the  upper  wall  of  the  vagina.  The  two  canals  are  in  such 
close  apposition  that  you  can  feel  the  urethra  imbedded  in  the 
vagina  like  a  thick  cord.  The  urethra  is  slightly  curved  with  the 
concavity  upwards ;  but  for  all  practical  purposes  it  may  be  con- 

1  See  Burn's  Midwifery. 

2  See  Tiedemann,  Yonder  Duverneyschen  Driisen des  Weibs.  Heidelberg,  1840. 


524  DISSECTION   OF   THE   FEMALE   PERINEUM. 

sidered  straight.  Its  direction,  however,  is  not  horizontal.  In 
the  unimpregnated  state  it  runs  nearly  in  the  direction  of  the 
axis  of  the  outlet  of  the  pelvis ;  so  that  a  probe  pushed  on  in  the 
course  of  the  urethra  would  strike  against  the  promontory  of  the 
sacrum.  But,  after  impregnation,  when  the  uterus  begins  to  rise 
out  of  the  pelvis,  the  bladder  is  more  or  less  raised  also  in  con- 
sequence of  their  mutual  connection ;  therefore  the  urethra,  in  the 
latter  months  of  utero-gestation,  acquires  a  much  more  perpendi- 
cular course. 

The  female  urethra  is  provided  with  a  compressor  muscle, 
similar,  in  origin  and  arrangement,  to  that  which  surrounds  the 
membranous  part  of  the  urethra  in  the  male.  It  also  passes 
through  the  triangular  ligament.  The  prostate  gland  is  wanting, 

FIG.  124. 


1.  Meatus  urinarius.  /    j®%C2a^^.     \  3-  Bulb  °^  vagina. 

2.  Vagina.  /^~r*sF*lV\    \  4-  Clitoris  with  its  two  crura. 


BULB    OF    THE    VAGINA 


but  there  are  minute  glands  scattered  around  the  neck  of  the 
bladder.  In  consequence  of  the  wider  span  of  the  pubic  arch,  and 
the  more  yielding  nature  of  the  surrounding  structures,  the  female 
urethra  is  much  more  dilatable  than  the  male.  By  means  of  a 
sponge-tent,  it  may  be  safely  dilated  to  admit  the  easy  passage  of 
the  fore-finger  into  the  bladder.  Advantage  is  taken  of  this  great 
dilatability  in  the  extraction  of  calculi  from  the  bladder. 

The  mucous  coat  of  the  urethra  is  pale  and  arranged  in  longi- 
tudinal folds,  and  is  lined  by  squamous  epithelium,  which  changes 
to  the  spheroidal  variety  near  the  bladder.  Next  to  the  mucous 
coat  is  a  layer  of  elastic  and  non-striped  muscular  fibres  inter- 
mixed. The  muscular  tissue  is  arranged  in  two  layers  —  an  outer, 
consisting  of  circular  fibres,  and  an  inner  of  longitudinal  fibres. 

1  Taken  from  an  injected  preparation  in  the  Mus6e  Orfila,  at  Paris. 


DISSECTION   OF   THE   SIDE  VIEW   OF   THE   PELVIS.  525 

Externally  there  is  a  plexus  of  veins  bearing  a  strong  resemblance 
to  erectile  tissue. 

The  vagina  is  the  canal  which  leads  to  the 
uterus ;  at  present,  only  the  orifice  of  it  can  be 
seen.  It  is  surrounded  by  a  sphincter  muscle,  easily  displayed  by 
removing  the  integument.  The  muscle  is  about  three-fourths  of 
an  inch  broad,  and  connected  with  the  cutaneous  sphincter  of  the 
anus  in  such  a  manner  that  they  together  form  something  like  the 
figure  8. 

On  each  side  of  the  orifice  of  the  vagina,  between  the  mucous 
membrane  and  the  sphincter,  is  a  plexus  of  tortuous  veins,  termed 
the  bulb  of  the  vagina,  from  its  analogy  to  the  bulb  of  the  urethra 
in  the  male.  This  vaginal  bulb  is  about  an  inch  long  and  extends 
across  the  middle  line  between  the  meatus  urinarius  and  the 
clitoris,  as  shown  in  fig.  124. 

The  description  of  the  perineal  branches  of  the  pudic  vessels 
and  nerves,  given  in  the  dissection  of  the  male  perineum,  applies, 
mutatis  mutandis,  to  the  female,  excepting  that  they  are  propor- 
tionably  small,  and  that  the  artery  which  supplies  the  bulb  of  the 
urethra  in  the  male  is  distributed  to  the  bulb  of  the  vagina  in  the 
female. 


ANATOMY  OF  THE   SIDE   VIEW   OF   THE   PELVIC 
VISCERA. 

To  obtain  a  side  view  of  the  pelvic  viscera,  the 
left  innominate  bone  should  be  removed  thus : — 
Detach  the  peritoneum  and  the  levator  ani  from  the  left  side  of  the 
pelvis,  cut  through  the  external  iliac  vessels,  the  obturator  vessels 
and  nerve,  and  the  nerves  of  the  lumbar  plexus ;  then  saw  through 
the  os  pubis  about  two  inches  external  to  the  symphysis,  and  cut 
through  the  sacro-iliac  symphysis ;  now  draw  the  legs  apart,  and 
saw  through  the  base  of  the  spine  of  the  ischium ;  after  cutting 
through  the  pyriformis,  the  great  sacro-sciatic  ligament,  the 
great  and  small  sciatic  nerves,  and  the  gluteus  maximus  muscle, 
the  innominate  bone  can  be  easily  detached.  This  done,  the  rectum 


526 


SIDE   VIEW   OF  THE   PELVIC   VISCEEA. 


should  be  distended  with  tow,  and  the  bladder  blown  up  through 
the  ureter.  A  staff  should  be  passed  through  the  urethra  into  the 
bladder,  and  a  block  placed  under  the  sacrum. 

The  reflection  of  the  peritoneum  as  it  passes  from  the  front  of 
the  rectum  to  the  lower  part  of  the  bladder  (forming  the  recto- 
vesical  pouch),  and  thence  over  the  back  of  the  bladder  to  the  wall 
of  the  abdomen,  has  been  already  described.  You  see  where  the 


FIG.  125. 


Peritoneum  in 
clotted  out- 
line. .  .  . 


Corpus  cavern- 
osum  penis  . 

Triangular 
ligament .     . 


Prostate 


VERTICAL   SECTION   THROUGH    THE   PERINEUM   AND    PELVIC   VISCEEA. 
(The  arrows  point  out  where  the  bladder  can  be  tapped.) 

distended  bladder  is  bare  of  peritoneum,  and  that  it  can  be  tapped 
either  through  the  rectum  or  above  the  pubes  without  injury  to  the 
serous  membrane,  as  shown  by  the  arrows  in  fig.  125. 

FALSE  LIGA-  ^ne  peritoneal  connections  of  the  bladder  are 

MENTS  OF  TUB  called  its  false  ligaments ;  false  in  contradistinction 

BLADDER.  to  the  true,  which  are  formed  by  the  fascia  of  the 


SIDE   VIEW   OF  THE   PELVIC   VISCERA. 


527 


pelvis,  and  really  do  sustain  the  neck  of  the  bladder  in  its  proper 
position.  The  false  ligaments  are  five  in  number,  two  posterior, 
two  lateral,  and  one  superior.  The  posterior  are  produced  by  two 
peritoneal  folds,  one  on  either  side  the  recto-vesical  pouch ;  the  two 
lateral,  by  reflections  of  the  peritoneum  from  the  sides  of  the  pelvis 


FIG.  126. 


'<_  Iliac  fascia 
covering 
iliacus. 


Pelvic  fascia 
dividing. 

Obturator  fascia 
covering  obtu- 
rator interims. 

Recto-vesical 
layer  covering 
levator  ani. 


Anal  fascia. 


TRANSVERSE   SECTION   OP   THE    PELVIS,    TO   SHOW   THE    REFLECTIONS  OF 
THE   PELVIC   FASCIA.       (AFTEB   GEAY.) 

to  the  sides  of  the  bladder;  the  superior. fa  produced  by  the  passage 
of  the  peritoneum  from  the  front  of  the  bladder  to  the  abdominal 
wall.  These  have  been  already  described  (p.  503). 

To   expose   the   pelvic   fascia,  the   peritoneum 
PELVIC  FASCIA.  ,  *  '  r  .   . 

must   be  removed  from  that  side   of   the  pelvis 

which  has  not  been  disturbed :  in  doing  so,  notice  the  abundance 
of  loose  connective  tissue  interposed  between  the  peritoneum  and 


528  PELVIC   FASCIA. 

the  fascia,  to  allow  the  bladder  to  distend  with  facility.  When- 
ever urine  is  extravasated  into  this  loose  tissue,  it  is  sure  to  pro- 
duce the  most  serious  consequences ;  therefore  in  all  operations  on 
the  perineum,  it  is  of  the  utmost  importance  not  to  injure  this  fascia. 

The  pelvic  fascia  is  a  thin  but  strong  membrane,  and  constitutes 
the  true  ligaments  of  the  bladder  and  the  other  pelvic  viscera,  sup- 
porting and  maintaining  them  in  their  proper  position. 

Examine,  first,  to  what  parts  of  the  pelvis  the  fascia  is  attached ; 
secondly,  the  manner  in  which  it  is  reflected  on  the  viscera. 

Beginning,  then  (fig.  126),  we  see  that,  in  front,  the  fascia  is 
continuous  with  the  transversalis  fascia,  and  laterally  with  the  iliac 
fascia,  and  that  superiorly  it  is  attached  to  the  body  of  the  os  pubis, 
to  the  brim  of  the  pelvis,  and  to  the  side  of  the  bone  just  above  the 
attachment  of  the  obturator  internus,  close  to  the  obturator  foramen 
and  the  great  sciatic  notch.  Here  it  becomes  gradually  thinner, 
covers  the  pyriformis  and  the  sacral  plexus,  and  is  gradually  lost 
on  the  front  of  the  sacrum. 

Traced  forwards,  we  find  that  it  is  attached  to  the  bone  along 
the  upper  border  of  the  obturator  internus,  and,  as  it  passes  for- 
wards over  the  obturator  foramen,  completes  the  canal  through 
which  the  obturator  vessels  pass  to  the  foramen  ;  anteriorly,  it  is 
attached  to  the  posterior  surface  of  the  lower  part  of  the  symphysis 
pubis.  From  this  attachment  the  fascia  descends  as  far  as  a  line 
drawn  from  the  spine  of  the  ischium  to  the  pubic  symphysis, 
where  it  forms  a  dense  white  line  which  marks  the  division  of  the 
fascia  into  two  layers,  an  outer,  the  obturator,  and  an  inner,  the 
recto-vesical  fascia.  It  also  serves  for  the  attachment  of  a  consider- 
able part  of  the  middle  portion  of  the  levator  ani. 

The  obturator  fascia,  the  outer  layer,  is  the  continuation  of  the 
pelvic  fascia,  and  descends  on  the  inner  surface  of  the  obturator 
internus,  forming  at  the  same  time  a  sheath  for  the  pudic  vessels 
and  nerve,  the  nerve  being  the  lowest.  It  is  attached  to  the  pubic 
arch,  to  the  tuberosity  of  the  ischium,  and  to  the  margin  of  the 
great  sacro-sciatic  ligament.  It  is  continuous  in  front,  below  the 
symphysis  pubis,  with  the  corresponding  layer  of  the  opposite  side, 
and  here  forms  the  posterior  layer  of  the  triangular  ligament. 
From  this  fascia  is  derived  the  iscJiio-^fectal  or  anal  fascia,  which 


PELVIC    VISCERA   IN   THE   MALE.  529 

lines  the  under  or  perineal  surface  of  the  levator  ani,  and  is  subse- 
quently lost  upon  the  side  of  the  rectum. 

The  recto-vesical  fascia  descends  on  the  upper  or  internal  surface 
of  the  levator  ani,  and  invests  the  bladder,  prostate,  and  rectum. 
From  the  symphysis  pubis  it  is  reflected  over  the  prostate  and  the 
neck  of  the  bladder  to  form,  on  either  side  of  the  symphysis,  two 
well-marked  bands  —  the  anterior  true  ligaments  of  the  bladder. 
From  the  side  of  the  pelvis  it  is  reflected  on  to  the  side  of  the 
bladder,  constituting  the  lateral  true  ligaments  of  that  viscus,  and 
encloses  the  prostate  and  the  vesical  plexus  of  veins.  A  prolonga- 
tion from  this  ligament  encloses  the  vesicula  seminalis,  the  lower 
layer  of  which  passes  between  the  bladder  and  the  rectum,  to  join 
its  fellow  from  the  opposite  side.  The  continuation  of  the  recto- 
vesical  fascia  covers  the  remainder  of  the  upper  surface  of  the 
levator  ani  as  far  as  its  attachment  to  the  rectum,  where  it  is 
reflected  round  this  tube. 

GENERAL  ^^e  P6^0  viscera  are  so  surrounded  by  veins 

POSITION  OF  THE  and  loose  areolar  tissue,  that  he  who  dissects  them 
PELVIC  VISCERA  for  the  first  time  will  find  a  difficulty  in  discovering 
IN  THE  MALE.  ^eir  definite  boundaries.  The  rectum  runs  at  the 

back  of  the  pelvis,  and  follows  the  anterior  curve  of  the  sacrum  and 
ooccyx.  The  bladder  lies  in  front  of  the  rectum,  immediately 
behind  the  symphysis  pubis.  At  the  neck  of  the  bladder  is  the 
prostate  gland  through  which  the  urethra  passes.  In  the  cellular 
tissue,  between  the  bladder  and  the  rectum,  there  is,  on  each  side, 
a  convoluted  tube,  called  the  vesicula  seminalis,  and  on  the  inner 
side  of  each  vesicula  is  the  seminal  duct  or  vas  deferens.  Before 
describing  these  parts  in  detail,  it  is  necessary  to  say  a  few  words 
about  the  large  tortuous  veins  which  surround  them. 

VESICO-PRO-  Beneath  the  pelvic  fascia  surrounding  the  pro- 

STATIC  PLEXUS  state  and  the  neck  of  the  bladder  are  large  and 
OF  VEINS.  tortuous  veins,  which  form  the  prostatic  and  the 

vesical  plexuses.  They  empty  themselves  into  the  internal  iliac. 
In  early  life  they  are  not  much  developed,  but  as  puberty  approaches 
they  gradually  increase  in  size,  and  one  not  familiar  with  the 
anatomy  of  these  parts  would  hardly  credit  the  size  which  they 
sometimes  attain  in  old  persons.  They  communicate  freely  behind 

M  M 


530 


VESICO-PROSTATIC   PLEXUS   OF   VEINS. 


with  the  inferior  heemorrhoidal  plexus,  or  veins  about  the  anus,  and 
they  receive  the  blood  returning  from  the  penis  through  the  large 
veins  which  pass  under  the  pubic  arch. 

If,  in  lithotomy,  the  incision  be  carried  beyond  the  limits  of 


FIG.  127. 


SIDE    VIEW    OF    THE    PELVIC    VISCERA. 
(Taken  from  a  Photograph.) 


1.  External  sphincter. 

2.  Internal  sphincter. 

3.  Levator  ani  cut  through. 

4.  Accelerator  urinte. 

5.  Membranous  part  of  the  urethra,  sur- 

rounded by  compressor  muscle. 

6.  Prostate  gland. 


7.  Vesicula  seminalis. 

8.  Ureter. 

9.  Vas  deferens. 

10.  Crus  penis  divided. 

11.  Triangular  ligament. 

12.  Superficial  perineal  fascia. 

13.  Rectum. 


th  e  prostate,  the  great  veins  around  it  must  necessarily  be  divided  ; 
these,  independently  of  any  artery,  are  quite  sufficient  to  occasion 
serious  haemorrhage. 


RELATIONS  OF  THE  RECTUM.  531 

RECTUM  AND  The  rectum  is  about  eight  inches  long.  It  is  a 

ITS  RELATIONS.  continuation  of  the  sigmoid  flexure  of  the  colon, 
enters  the  pelvis  at  the  left  sacro-iliac  articulation,  describes  a 
curve  corresponding  to  the  sacrum  and  coccyx,  and  terminates  at 
the  anus.  The  rectum  also  inclines  from  the  left  side  to  the 
middle  line,  and  before  its  termination,  the  bowel  turns  downwards 
so  that  the  anal  aperture  is  dependent.  Although  it  loses  the 
sacculated  appearance,  it  is  not  throughout  of  equal  calibre  and  its 
capacity  becomes  greater  as  it  descends  into  the  pelvis ;  immedi- 
ately above  the  sphincter,  it  presents  a  considerable  dilatation,  the 
ampulla  (fig.  125).  This  dilatation  is  not  material  in  early  life,  but 
it  increases  as  age  advances.  Under  such  circumstances  the  rectum 
loses  altogether  its  cylindrical  form,  and  bulges  up  on  either  side 
of  the  prostate  and  the  base  of  the  bladder.  For  this  reason  the 
rectum  should  always  be  emptied  before  the  operation  of  lithotomy. 

The  rectum  is  conveniently  divided  into  three  portions,  the 
upper,  the  middle,  and  the  lower. 

The  upper  portion  is  about  three  inches  and  a  half  in  length, 
and  extends  as  low  as  the  third  bone  of  the  sacrum,  to  which  bone 
it  is  connected  by  a  fold  of  peritoneum,  termed  the  meso-rectum. 
In  this  fold,  the  terminal  branch  of  the  inferior  mesenteric  artery 
with  its  vein  runs  down  to  supply  the  bowel.  This  portion  of  the 
rectum  has  behind  it,  the  sacral  plexus  of  nerves,  the  pyriformis, 
and  some  branches  of  the  left  internal  iliac  artery ;  in  front,  it  has 
the  bladder  and  the  recto-vesical  pouch. 

The  middle  portion  comprises  three  inches  in  length,  and  is 
continuous  with  the  lower  portion  at  the  tip  of  the  coccyx.  It  is 
connected  posteriorly  to  the  sacrum  and  coccyx  by  loose  connective 
tissue,  and  is  covered  by  peritoneum  only  in  front  in  the  upper 
part,  which  forms  the  recto-vesical  pouch.  It  has  in  front,  the 
fundus  of  the  bladder,  the  vesiculae  seminales,  the  vasa  deferentia 
and  the  prostate  ;  while  in  the  female  it  is  closely  connected  to  the 
posterior  wall  of  the  vagina. 

The  lower  portion  comprises  the  lowest  inch  and  a  half  of  the  rec- 
tum. It  is  entirely  destitute  of  peritoneum,  and  is  supported  by  the 
levatores  ani,  the  larger  portions  of  which  are  inserted  into  its  side ;  it 
has  also  surrounding  it,  the  internal,  and  lastly  the  external  sphincters. 

M   M   2 


532  DIGITAL    EXAMINATION    OF   THE    RECTUM. 

There  is  a  considerable  interval  between  it  and  the  membranous 
portion  of  the  urethra  in  the  male,  and  the  vagina  in  the  female. 

DIGITAL  Tne  relations  of  the  front  part  of  the  rectum — 

EXAMINATION  OF        that,  namely,  included  between  the  recto-vesical 
THE  KECTUM.  pouch  and  the  anus — are  most  important.     If  the 

fore-finger  be  introduced  into  the  anus,  and  a  catheter  into  the 
urethra,  the  first  thing  felt  through  the  front  wall  of  the  bowel  is 
the  membranous  part  of  the  urethral[nLg7l25).  It  lies  just  within 
the  sphincter,  and  is  about  ten  lines  in  front  of  the  gut.  About 
one  and  a  half  or  two  inches  from  the  anus  the  finger  comes  upon 
the  prostate  gland ;  this  is  in  close  contact  with  the  gut,  and  is 
readily  felt  on  account  of  its  hardness ;  by  moving  the  finger  from 
side  to  side  we  recognise  its  lateral  lobes.  Still  higher  up,  the 
finger  goes  beyond  the  prostate,  and  reaches  the  trigone  of  the 
bladder  :  the  facility  with  which  this  can  be  examined  depends, 
not  only  upon  the  length  of  the  finger  and  the  amount  of  fat  in 
the  perineum,  but  upon  the  degree  of  distension  of  the  bladder  ; 
the  more  distended  the  bladder,  the  better  can  the  prostate  be  felt. 
These  several  relations  are  practically  important.  They  explain 
why,  with  the  finger  in  the  rectum,  we  can  ascertain  whether 
the  catheter  is  taking  the  right  direction — whether  the  prostate 
be  enlarged  or  not.  We  might  even  raise  a  stone  from  the 
bottom  of  the  bladder  so  as  to  bring  it  in  contact  with  the  forceps. 
The  rectum  is  supplied  with  blood  by  the  superior,  middle,  and 
inferior  haemorrhoidal  arteries.  The  superior  comes  from  the  in- 
ferior mesenteric  (p.  473)  ;  the  middle  from  the  anterior  division 
of  the  internal  iliac  artery,  and  the  inferior  from  the  pudic  artery. 
The  superior  haemorrhoidal  veins  join  the  inferior  mesenteric,  and 
consequently  the  portal  system ;  the  middle  and  the  inferior 
heemorrhoidal  veins  join  the  internal  pudic,  and  thence  the  internal 
iliac  vein.  They  are  very  large  and  form  loop-like  plexuses  about 
the  lower  part  of  the  rectum.  Having  no  valves,  they  are  liable  to 
become  dilated  and  congested  from  various  internal  causes  ;  hence 
the  frequency  of  hsemorrhoidal  affections. 

This  viscus,  being  a  receptacle  for  the  urine, 
BLADDER.  .,  .        .  -.  -..      ,      ,, 

must  necessarily  vary  in  size,  and  accordingly  the 

nature  of  its  connections  and   coats   is  such   as  to  permit   this 


POSITION   OF   THE    BLADDER. 


533 


variation.  When  contracted,  the  bladder  sinks  into  the  pelvis 
behind  the  pubic  arch,  and  is  completely  protected  from  injury. 
But,  as  it  gradually  distends,  it  rises  out  of  the  pelvis  into  the 
abdomen,  and,  in  cases  of  extreme  distension,  may  reach  up  to  the 
umbilicus.1  Its  outline  can  then  be  easily  felt  through  the  walls 
of  the  abdomen.  The  form  2  of  the  distended  bladder  is  oval,  and 
its  long  axis,  if  prolonged,  would  pass  superiorly  through  the  um- 
bilicus, and  inferiorly  through  the  end  of  the  coccyx.  The  axis  of 
a  child's  bladder  is  more  vertical  than  that  of  the  adult ;  for  in 

FIG.  128. 


1.  Ureter. 

2.  Vas  deferens. 


3.  Vesicula  semimli* 

4.  Trigone. 

5.  Prostate. 


POSTERIOR   VIEW    OF    THE    BLADDER. 


children  the  bladder  is  not  a  pelvic  viscus.     This  makes  lithotomy 
in  them  so  much  more  difficult. 

1  When  the  bladder  is  completely  paralysed  it  becomes  like  an  inorganic  sac, 
and  there  seems  to  be  no  limit  to  its  distension.     Hall  found,  in  a  drunkard,  the 
bladder  so  dilated  that  it  would  hold  twenty  pints  of  water.     (Elem.  Phys.  art. 
Vesica.)     Frank  saw  a  bladder  so  distended  as  to  resemble  ascites,  and  evacuated 
from  it  twelve  pounds  of  urine.     (Oratio  de  Signis  Morbomm,  &c.  &c.     Ticini, 
1788.) 

W.  Hunter,  in  his  Anatomy  of  the  Gravid  Uterus,  has  given  the  representation 
of  a  bladder  distended  nearly  as  high  as  the  ensiform  cartilage. 

2  In  all  animals  with  a  bladder,  the  younger  the  animal  the  more  elongated  is 
the  bladder.     This  is  indicative  of  its  original  derivation  from  a  tube,  i.e.  the 
uraclius.    In  the  infant,  the  bladder  is  of  a  pyriform  shape,  as  it  is,  permanently, 
in  the  quadruped ;  but  as  we  assume  more  and  more  the  perpendicular  attitude,  the 
weight  of  the  urine  gradually  makes  the  lower  part  more  capacious. 


534  THE    BLADDER. 

The  quantity  of  urine  which  the  bladder  will  hold  without 
much  inconvenience  varies.  As  a  general  rule,  it  may  be  stated 
at  about  a  pint.  Much  depends  upon  the  habits  of  the  individual ; 
but  some  persons  have,  naturally,  a  very  small  bladder,  and  are 
obliged  to  empty  it  more  frequently. 

In  young  persons  the  lowest  part  of  the  bladder  is  the  neck, 
or  that  part  which  joins  the  prostate.  But  as  age  advances,  the 
bottom  of  the  bladder  gradually  deepens7  so  as  to  form  a  pouch 
behind  the  prostate.  In  old  subjects,  particularly  if  the  prostate 
be  enlarged,  this  pouch  becomes  deep,  micturition  becomes  tedious, 
and  the  bladder  cannot  completely  empty  its  contents.  It  some- 
times happens  that  a  stone  in  the  bladder  is  not  felt ;  the  reason 
of  which  may  be  that  the  stone,  lodged  in  such  a  pouch  below  the 
level  of  the  neck  of  the  bladder,  escapes  the  detection  of  the  sound. 
Under  these  circumstances,  if  the  patient  be  placed  on  an  inclined 
plane  with  the  pelvis  higher  than  the  shoulders,  the  stone  falls  out 
of  the  pouch,  and  is  easily  struck. 

The  bladder  is  divided  into  a  summit,  a  body,  a  base,  and  a 
neck. 

The  summit  is  its  highest  part,  and  to  it  is  attached  a  thin 
fibrous  cord,  the  urachus,  which  passes  up  to  the  umbilicus,  and  is 
the  obliterated  remains  of  a  canal  connecting  the  foetal  bladder 
with  a  sac  external  to  the  foetus,  called  the  allantois. 

The  body  on  its  anterior  aspect  is  not  covered  with  peritoneum, 
and  is  in  relation  with  the  symphysis  pubis,  the  triangular  liga- 
ment, and  the  obturator  internus  ;  posteriorly,  it  is  covered  with 
peritoneum,  and  is  in  relation  in  the  male  with  the  rectum,  and  in 
the  female  with  the  uterus ;  laterally,  it  is  only  covered  with  peri- 
toneum behind,  and  is  in  relation  with  the  obliterated  hypogastric 
arteries,  the  vasa  deferentia,  and  ureters. 

The  base  is  the  lowest  part  of  the  bladder  resting  upon  the  middle 
portion  of  the  rectum,  and  is  only  slightly  covered  behind  with 
peritoneum ;  below,  it  is  in  contact  with  the  vesiculae  seminales  and 
vasa  deferentia,  which  latter  pass  forwards  as  far  as  the  prostate  ; 
the  reflection  of  the  peritoneum  posteriorly  with  the  vasa  defe- 
rentia converging  towards  the  front,  forms  a  triangular  space 
through  which  the  bladder  is  tapped  in  cases  of  retention  of  urine. 


URETER  AND  VAS  DEFERENS.  535 

The  neck  is  the  narrow  portion  where  the  urethra  begins,  and 
its  direction  is  downwards  and  forwards.  It  is  embraced  by  the 
prostate  gland. 

The  ureter  l  is  about  seventeen  inches  long,  and 

conveys  the  urine  from  the  kidney  to  the  bladder. 
In  the  dissection  of  the  abdomen  (p.  477),  it  was  seen  descending 
•alccg  the  psoas  muscle,  behind  the  spermatic  vessels,  and  crossing 
the  common  iliac  artery  into  the  pelvis.  Tracing  it  downwards, 
in  the  posterior  false  ligament  of  the  bladder,  below  the  obliterated 
hypogastric  artery,  we  find  that  it  runs  along  the  side  of  the 
bladder,  external  to  the  vas  deferens,  and  enters  it  about  an  inch 
and  a  half  behind  the  prostate,  and  about  two  inches  from  its 
fellow  of  the  opposite  side  (fig.  128).  It  perforates  the  bladder 
very  obliquely,  so  that  the  aperture,  being  valvular,  allows  the 
urine  to  flow  into,  but  not  out  of  it.  The  narrowest  part  of  the 
ureter  is  at  the  vesical  orifice ;  here,  therefore,  a  calculus  is  more 
likely  to  be  arrested  in  its  progress  than  at  any  other  part  of  the 
canal. 

This  tube,  about  twenty-four  inches  in  length, 

conveys  the  seminal  fluid  from  the  testicle  into 
the  prostatic  part  of  the  urethra.  Taking  its  origin  at  the  lower 
part  of  the  globus  minor  behind  the  testis,  it  ascends  at  the  back 
part  of  the  testis  and  epididymis,  along  the  back  of  the  spermatic 
cord  through  the  inguinal  canal  into  the  abdomen ;  then,  leaving 
the  cord  at  the  inner  ring,  it  curves  round  the  deep  epigastric 
artery,  then  crosses  over  the  external  iliac  vessels,  and  descends 
into  the  pelvis  on  the  side  of  the  bladder,  gradually  approaching 
nearer  the  middle  line.  Before  it  reaches  the  prostate,  it  passes  be- 
tween the  bladder  and  the  ureter ;  then,  becoming  very  sacculated, 
it  runs  forwards  internal  to  the  vesicula  seminalis,  and  is  joined  by 
the  duct  of  this  vesicle.  The  common  duct  thus  formed,  ductus 
communis  ejaculatorius,  terminates  in  the  lower  part  of  the  pro- 
static  portion  of  the  urethra  (fig.  128,  p.  533).  In  point  of  size 
and  hardness,  the  vas  deferens  has  very  much  the  feel  of  whipcord,2 
its  canal  not  being  more  than  ^th  of  an  inch  in  diameter. 

1  From  ovpfca,  I  pass  urine. 

*  The  description  in  the  text  assumes  the  bladder  to  be  distended.     But  when 


536  THE    PROSTATE. 


These  are  situated,  one  on  either  side,  between 
SEMINALES.  •  the  base  of  the  bladder  and  the  rectum,  and  serve 
as  reservoirs  for  the  fluid  secreted  by  the  testes,  and  also  secrete 
themselves  a  fluid  accessory  to  that  of  the  testicles  (fig.  127). 
Each  is  a  tube,  but  so  convoluted  that  it  is  like  a  little  sacculated 
bladder.  When  rolled  up,  the  tube  is  about  two  and  a  half  inches 
long,  and  a  quarter  of  an  inch  in  breadth  ;  unrolled,  it  would  be 
more  than  twice  that  length,  and  about  the  size  of  a  small  writing 
quill.  Several  caecal  prolongation's  proceed  from  the  main  tube, 
after  the  manner  of  a  stag's  horn.  The  vesiculee  seminales  do  not 
run  parallel,  but  diverge  from  each  other,  posteriorly,  as  far  as  the 
reflection  of  the  recto-vesical  peritoneal  pouch,  like  the  branches 
of  the  letter  V  ;  and  each  lies  immediately  on  the  outer  side  of  the 
vas  deferens,  into  which  it  opens. 

The  vesiculge  seminales  contain  a  brownish-coloured  fluid,. 
presumed  to  be  in  some  way  accessory  to  the  function  of  gene- 
ration.1 

PEOSTATE  The  prostate  gland  2  is  situated  at  the  neck  of 

GLAND.  the  bladder,  and  surrounds  the  first  part  of  the 

urethra  (fig.  127).  In  the  healthy  adult  it  is  about  the  size  and 
shape  of  a  chestnut.  Its  apex  is  directed  forwards  as  far  as  the 
deeper  layer  of  the  triangular  ligament.  It  is  surrounded  by  a 
plexus  of  veins  (p.  529),  and  is  maintained  in  its  position  by  the 
pelvic  fascia  (p.  529).  Its  upper  surface  is  about  three-quarters  of 
an  inch  below  the  symphysis  pubis  ;  its  apex  is  about  one  inch  and 
a  half  from  the  anus  ;  the  base  is  about  two  and  a  half. 

Above  the  prostate  are  the  pubo-prostatic  or  anterior  ligaments 
of  the  bladder,  with  the  dorsal  vein  of  the  penis  between  them  ; 
below,  and  in  contact  with  it,  is  the  rectum  ;  on  each  side  of  it  is 
the  levator  ani  ;  in  front  of  it  are  the  membranous  part  of  the 
urethra  (surrounded  by  its  compressor  muscle),  and  the  triangular 

the  bladder  is  empty,  the  vas  deferens  runs  down  upon  the  side  of  the  pelvis.  In 
this  course  it  may  be  seen,  through  the  peritoneum,  crossing  —  1,  the  external  iliac 
vessels  ;  2,  the  remains  of  the  umbilical  artery  ;  3,  the  obturator  artery  and  nerve  ; 
4,  the  ureter. 

1  The  vesiculffi  seminales  are  imperfectly  developed  till  the  age  of  puberty.     In 
a  child  three  years  of  age  they  can  hardly  be  inflated  with  the  blowpipe. 

2  From  irpoiffT-qui,  to  stand  before. 


URETHRA  BENEATH  THE  PUBIC  ARCH.  537 

ligament;  behind,  are  the  neck  of  the  bladder  and  the  vesiculse 
seminales  with  the  ejaculatoiy  ducts. 

The  transverse  diameter  is  about  one  inch  and  a  half;  the 
vertical  is  about  half  an  inch  less.  But  the  gland  varies  in  size  at 
different  periods  of  life.  In  the  child  it  is  imperfectly  developed : 
it  gradually  grows  towards  puberty,  and  generally  increases  in  size 
with  advancing  age. 

To  ascertain  the  size  and  condition  of  the  prostate  during  life, 
the  bladder  should  be  at  least  half  full :  the  prostate  is  then  pressed 
down  towards  the  rectum,  and  readily  within  reach  of  the  finger. 

The  urethra  is  a  canal  about  eight  inches  in 
ANATOMY  OF  & 

THE  URETHRA  length,  and  leads  from  the  bladder  to  the  end  of 

IN  ITS  PASSAGE  the  penis.     It  is  divided  into  three  portions — the 

prostatic,  the  membranous,  and  the  spongy.  At 
present  only  the  relations  of  the  membranous  part, 
which  comprises  that  part  of  the  canal  between  the  prostate  and 
the  bulb,  can  be  examined.  The  urethra  in  this  part  is  the 
narrowest  part  of  the  canal,  and  measures  three-quarters  of  an  inch 
on  its  upper  surface,  and  one-half  on  its  lower  surface,  in  conse- 
quence of  the  encroachment  of  the  bulb.  In  its  passage  under  the 
pubic  arch,  it  is  surrounded  by  the  compressor  urethree,  and  below 
it  are  Cowper's  glands.  It  traverses  the  two  layers  of  the  triangu- 
lar ligament,  and  is  about  an  inch  below  the  symphysis  pubis,  from 
which  it  is  separated  by  the  dorsal  vessels  and  nerves  of  the  penis, 
and  by  some  connective  and  muscular  tissue ;  it  is  nearly  the  same 
distance  above  the  rectum ;  it  is  not,  however,  equidistant  from 
this  portion  of  the  intestine  at  all  points,  because  of  the  downward 
bend  which  the  rectum  makes  towards  the  anus.1 

The  membranous  part  of  the  urethra  in  children  is  very  long, 
owing  to  the  smallness  of  the  prostate  at  that  period  of  life  ;  it 
is  also  composed  of  thin  and  delicate  walls,  and  lies  close  to  the 
rectum.  In  sounding  a  child,  therefore,  it  is  very  necessary  not  to 
use  violence,  else  the  instrument  is  likely  to  pass  through  the  coats 
of  the  urethra  and  make  a  false  passage. 

1  If  a  clean  vertical  section  were  made,  we  should  see  that  the  two  canals  form 
the  sides  of  a  triangular  space,  of  which  the  apex  is  towards  the  prostate.  This 
is  sometimes  called  the  recto -urethral  triangle. 


538  LEVATOR  ANI  AND  COCCYGEUS. 

This  muscle  supports  the  anus  and  lower  part 
of  the  rectum  like  a  sling ;  and,  with  the  coccy- 
geus  and  compressor  urethras,  forms  a  muscular  floor  for  the  cavity 
of  the  pelvis.  To  see  the  muscle,  the  pelvic  fascia  must  be  reflected 
from  its  upper  surface.  It  arises  in  front,  from  the  posterior  aspect 
of  the  os  pubis  near  the  syinphysis ;  behind,  from  the  inner  surface  of 
the  spine  of  the  ischium ;  and,,  between  these  bones,  from  the  ten- 
dinous line  which  marks  the  division ,  of  the  pelvic  fascia  into  the 
obturator  and  recto-vesical  layers  (p.  527).  From  this  long  origin 
the  fibres  descend  inwards  towards  the  middle  line,  and  are  inserted 
thus — the  anterior,  the  longest,  passing  under  the  prostate,  meet 
their  fellow  in  the  middle  line  of  the  perineum  in  front  of  the  anus 
(forming  the  levator  prostatce),  joining  the  fibres  of  the  transversus 
perinei  and  the  external  sphincter  at  the  central  tendon  of  the 
perineum;  the  middle,  the  most  numerous,  are  inserted  into  the 
side  of  the  rectum ;  the  posterior  are  inserted,  partly  into  the  coccyx, 
and  partly  into  the  median  raphe  between  the  coccyx  and  the 
anus,  and  meet  their  fellow  beneath  the  rectum. 

The  levator  ani  is  supplied  by  the  inferior  hasmorrhoidal,  the 
two  lower  sacral,  and  the  coccygeal  nerves. 

The  action  of  the  levatores  ani  is  to  retract  the  anus  and  the 
rectum  after  it  has  been  protruded  in  defagcation  by  the  combined 
action  of  the  abdominal  muscles  and  the  diaphragm. 

This  muscle  is  placed  behind  the  levator  ani, 
and  should  be  regarded  as  a  continuation  of  that 
muscle.  It  is  triangular  in  shape,  and  arises  by  its  apex  from  the 
spine  of  the  ischium  and  the  lesser  sacro-sciatic  ligament,  gradually 
spreads  out,  and  is  inserted  into  the  side  of  the  lower  part  of  the 
sacrum  and  the  coccyx.  Its  posterior  fibres  are  in  relation  with 
the  pyriformis,  its  anterior  fibres  are  continuous  with  the  levator 
ani.  This  muscle  is  supplied  by  the  two  lower  sacral  and  the 
coccygeal  nerves. 

At  this   stage  of  the    dissection,   the   bladder 

should  be. drawn  downwards,  and  the  branches  of 

the  internal  iliac  artery  and  the  sacral  plexus  clearly  displayed  on 

the  right  side,  by  carefully  clearing  away  the  prolongations  of  the 

pelvic  fascia  which  surround  them. 


INTERNAL   ILIAC    ARTERY. 


539 


INTERNAL 
ILIAC  ARTERY 
AND  BRANCHES. 


From  the  division  of  the  common  iliac  artery, 
the  internal  iliac  descends  into  the  pelvis,  and, 
after  a  course  of  about  an  inch  and  a  half,  divides, 
opposite  the  great  sacro-sciatic  notch,  into  two  large  branches,  an 
anterior  and  a  posterior  (fig.  129).  The  artery  lies  upon  the  lumbo- 
sacral  cord,  the  pyriformis  muscle,  the  external  and  internal  iliac 
veins ;  the  ureter,  enclosed  in  the  posterior  false  ligament  of  the 
bladder,  passing  in  front :  the  psoas  lies  to  its  outer  side  at  the 
commencement  of  its  course. 

FIG.  129. 


MEU 


PUD 


SAC  LAT  . 

PLAN    OF    THE    BRANCHES    OF    THE    INTERNAL    ILIAC    ARTERY. 

The  posterior  division  gives  off  the  ilio-lumbar,  lateral  sacral, 
and  gluteal  arteries ;  the  anterior  gives  off  the  superior  vesical, 
obturator,  inferior  vesical,  middle  hgemorrhoidal,  sciatic  and  pudic  ; 
also  the  uterine  and  vaginal  in  the  female.  Such  is  their  usual 
order;  but  these  branches,  though  constant  as  to  their  general 
distribution,  vary  as  to  their  origin. 

The  branches  of  the  posterior  division  are — 

a.  The  ilio-lumbar  is  analogous  to  the  lumbar  branches  of  the 
aorta.  It  ascends  beneath  the  psoas  and  the  external  iliac  vessels 
to  get  to  the  superficial  surface  of  the  iliacus.  Here  it  divides  into 
an  iliac  and  a  lumbar  branch ;  the  iliac  branch  supplies  branches  to 
the  iliacus,  a  branch  to  the  diploe  of  the  ilium,  and  a  large  branch 
along  the  iliac  crest,  which  finally  inosculates  with  the  deep 


540  BRANCHES   OF   THE   INTERNAL   ILIAC   ARTERY. 

circumflexa  ilii,  the  epigastric,  the  gluteal,  and  the  external  cir- 
cumflex arteries  ;  the  lumbar  branch  supplies  the  psoas  and  the 
quadratus  lumborum,  and  anastomoses  with  the  last  lumbar  artery ; 
it  distributes  a  small  branch  to  the  cauda  equina,  through  the 
foramen  between  the  last  lumbar  and  first  sacral  vertebrae. 

b.  The  lateral  sacral,  usually  two  in  number,  an  upper  and  a 
lower,  descend  in  front  of  the  sacral  foramina,  and  inosculate  on  the 
coccyx  with  the  middle  sacral  artery ;  the  upper  enters  one  of  the 
upper  sacral  foramina,  and,  after  supplying  the  structures  in  the 
sacral  canal,  emerges  on  the  back  through  one  of  the  posterior 
foramina  and  supplies  the  muscles  in  the  neighbourhood,  anasto- 
mosing with  the  gluteal  artery ;  the  lower  descends  in  front  of  the 
pyriformis,  supplying  branches  to  this  muscle,  the  bladder,  and 
rectum,  and  others  which  enter  the  anterior  sacral  foramina  for  the 
supply  of  the  cauda  equina,  and  finally  emerge  through  the  posterior 
sacral  foramina  to  end  in  the  muscles  and  skin  of  the  back :  this 
branch  inosculates  with  the  middle  and  lateral  sacral  arteries  and 
the  gluteal. 

c.  The  gluteal  is  the  largest  branch.    It  passes  immediately  out 
of  the  pelvis  through  the  great  sciatic  notch,  above  the  pyriformis 
muscle,  and  then  divides  into  a  superficial  and  deep  branch ;  the 
former   passes    beneath  the  gluteus  maximus ;   the  latter  passes 
between  the  gluteus  medius  and  minimus,  and  then  divides  into 
two   branches,   one  running  along   the  upper  attached  border  of 
the  gluteus  minimus,  the  other  passing  obliquely  across  the  same 
muscle    as   far  as  the  great  trochanter,   to    anastomose  with  the 
external  circumflex  artery.    These  will  be  dissected  with  the  gluteal 
region. 

The  anterior  division  gives  off — 

a.  The  superior  vesical  artery  which  comes  off  from  the  unoblite- 
rated  portion  of  the  hypogastric,  and  supplies  the  upper  part  of  the 
bladder.     It  gives  off  the  middle  vesical  artery,  which  supplies  the 
base  of  the  bladder  and  the  vesicula  seminalis ;  a  small  branch,  the 
deferential,  which  accompanies  the  vas  deferens  to  the  testis  and 
inosculates  with  the  spermatic  artery ;  and  smaller  branches  to  the 
ureter. 

b.  The  inferior  vesical  artery  which  ramifies  on  the  under  surface  of 


BRANCHES    OF   THE    INTERNAL    ILIAC    ARTERY. 


541 


the  bladder,  the  vesiculae  serninales,  and  the  prostate,  anastomosing 
with  branches  of  the  corresponding  artery  of  the  other  side. 

c.  The  middle  hcemorrhoidal  artery  which  usually  arises  in  con- 
junction with  the  preceding,  and  supplies  the  rectum,  inosculating- 
with  the  other  hgemorrhoidal  arteries. 

d.  The  obturator  artery  which  runs  along  the  side  of  the  pelvis, 
below  the  corresponding  nerve,  to  the  upper  part  of  the  obturator 
foramen,  through  which  it  passes  to  be  distributed  to  the  muscles  of 
the  thigh.     In  the  pelvis  it  lies  between  the  peritoneum  and  the 

FIG.  130. 


VIEW    OF    THE    DIFFERENT    DIRECTIONS    WHICH    AN    ABNORMAL    OBTURATOR   ARTEHY 
MAY  TAKE.       (SEEN    FROM   ABOVE.) 


A.  1.  Gimbernat's  ligament. 

2.  Femoral  ring. 

3.  Abnormal  obturator  artery. 

4.  External  iliac  vein. 

5.  External  iliac  artery. 

6.  Diminutive  obturator  artery  arising 

from  its  normal  source. 


B.  1.  Gimbernat's  ligament. 

2.  Abnormal  obturator  artery. 

3.  Femoral  ring. 

4.  External  iliac  vein. 

5.  External  iliac  artery. 

6.  Diminutive  obturator  artery. 


pelvic  fascia,  and  gives  off  a  small  branch  to  the  iliacus,  which 
anastomoses  with  the  ilio-lumbar;  a  vesical  branch,  which  passes 
backwards  to  supply  the  bladder ;  and  another,  the  pubic  branch, 
which  ramifies  on  the  back  of  the  os  pubis,  and  inosculates  with 
the  corresponding  branch  of  the  deep  epigastric  artery  and  with  its 
fellow  of  the  opposite  side.  External  to  the  pelvis  it  divides  into  an 
external  and  internal  branch,  which  respectively  skirt  the  outer 
and  inner  margins  of  the  obturator  foramen. 

The  obturator  artery  does  not,  in  all  subjects,  take  the  coursa 
above  stated,  since,  in  one  case  in  three  and  a  half,  it  arises  from  the 


542  BRANCHES   OF   THE   INTERNAL    ILIAC   ARTERY. 

deep  epigastric,  and  in  one  out  of  seventy-two  cases  it  has  its  origin 
by  a  branch  from  the  obturator  joining  a  branch  from  the  epigastric. 
It  may  arise  from  the  external  iliac  near  the  crural  arch,  or  by  a  short 
trunk  in  common  with  the  epigastric.1  Under  these  circumstances, 
in  order  to  reach  the  obturator  foramen,  it  generally  descends  on  the 
outer  side  of  the  femoral  ring.  Instances,  however,  occasionally 
occur,  where  it  makes  a  sweep  round  the  inner  side  of  the  ring ;  so 
that  three-fourths  of  the  ring,  or,  what  comes  to  the  same  thing,  of 
the  neck  of  a  femoral  hernia,  would  in  such  a  case  be  surrounded 
by  a  large  artery.2 

e.  The  sciatic  artery  is  the  larger  of  the  two  branches  into 
which  the  anterior  trunk  divides.  It  proceeds  over  the  pyriformis 
and  the  sacral  plexus,  to  the  lower  border  of  the  great  sciatic  notch, 
through  which  it  passes  out  of  the  pelvis  between  the  pyriformis 
and  coccygeus  to  the  buttock,  where  it  runs  with  the  great  sciatic 
nerve  between  the  great  trochanter  and  the  ischial  tuberosity.  It 
gives  off  small  muscular  branches  in  the  pelvis  to  the  pyriformis, 
coccygeus,  and  levator  ani ;  vesical  branches  to  the  bladder, 
prostate,  and  vesiculae  seminales;  and  hcemorrhoidal  branches  to 
the  rectum. 

/.  The  internal  pudic  artery  supplies  the  perineum,  scrotum  and 
penis.  In  the  pelvis  it  usually  lies  above  the  sciatic,  and  rests 
upon  the  pyriformis  and  sacral  plexus,  having  the  rectum  to  its 
inner  side.  It  passes  out  of  the  pelvis  through  the  great  sciatic 
foramen,  below  the  pyriformis  and  above  the  coccygeus,  crosses 
over  the  spine  of  the  ischium,  and  re-enters  the  pelvis  through  the 
lesser  foramen.  It  then  ascends  on  the  inner  side  of  the  obturator 
internus  towards  the  pubic  arch,  where  it  gives  branches  to  the 
several  parts  of  the  penis.  In  its  passage  on  the  inner  side  of  the 

1  In  most  subjects  a  small  branch  of  the  obturator  ascends  behind  the  ramus  of 
the  os  pubis  to  inosculate  with  the  epigastric.     The  variety  in  which  the  obturator 
arises  in  common  with  the  epigastric  is  but  an  unusual  development  of  this  branch. 
The   branch   derives  additional  interest  from    the  fact,   that    after   ligature   of 
the  external  iliac  it  becomes  greatly  enlarged,  and  carries  blood  directly  into  the 
epigastric.     See  a  case  in  Med.  Chir.  Trans,  vol.  xx.  1836. 

2  The  Museum  of  St.  Bartholomew's  Hospital  contains  two  examples  of  double 
femoral  herniae  in  the  male,  with  the  obturator  arising  on  each  side  from  the  epi- 
gastric.    In  three  out  of  the  four  ruptures  the  obturator  runs  on  the  inner  side  of 
the  mouth  of  the  sac. 


BRANCHES   OF  THE   INTERNAL   ILIAC   ARTERY.  543 

obturator  muscle  it  is  enclosed  in  a  strong  tube  of  fascia,  formed  by 
the  obturator  fascia,  and  is  situated  about  one  inch  and  a  quarter 
above  the  tuberosity  of  the  ischium.  It  now  ascends  under  cover 
of  the  ascending  ramus  of  the  ischium,  where  it  pierces  that  part 
of  the  pelvic  fascia  which  forms  the  posterior  layer  of  the  triangular 
ligament,  and  continues  its  course  close  to  the  ramus  of  the  os 
pubisj  between  the  two  layers  of  the  ligament,  the  anterior  layer  of 
which  it  pierces,  and  then  divides  into  the  artery  of  the  corpus 
cavernosum  and  the  dorsal  artery  of  the  penis.  Throughout  its 
course  it  is  accompanied  by  the  pudic  nerve  and  veins.  The 
branches  of  the  pudic  artery  were  described  in  the  dissection  of  the 
perineum  (p.  517). 

The  pudic  artery,  however,  sometimes  takes  a  very  different 
course.  Instead  of  passing  out  of  the  pelvis,  it  may  run  by  the 
side  of  the  prostate  gland  to  its  destination ;  or,  one  of  the  large 
branches  of  the  pudic  may  take  this  unusual  course,  while  the 
pudic  itself  is  regular,  but  proportionably  small.  Anatomists  are 
familiar  with  these  varieties,  and  a  winter  session  rarely  passes 
without  meeting  with  several  examples  of  them.  It  need  hardly 
be  said  that  lithotomy,  under  such  conditions,  might  be  followed 
by  a  large  hemorrhage. 

The  'middle- sacral  artery  is  a  small  branch  of  the  abdominal  aorta 
at  its  point  of  bifurcation.  It  descends  in  front  of  the  body  of  the 
fifth  lumbar  vertebra,  the  sacrum,  and  the  coccyx.  In  its  course 
it  gives  off  small  branches  to  the  rectum,  to  the  anterior  sacral 
foramina,  and  it  finally  inosculates  on  the  sacrum  and  the  coccyx 
with  the  lateral  sacral  arteries.  It  gradually  becomes  smaller  as  it 
passes  down  and  terminates  near  the  tip  of  the  coccyx  in  a  small 
body  about  the  size  of  a  pea,  called  the  coccygeal  or  Lusclika's  gland, 
which  has  been  previously  described  (p.  486). 

Respecting  the  veins  in  the  pelvis,  they  correspond  with  the 
arteries,  and  empty  themselves  into  the  internal  iliac  vein.  The 
remarkable  plexus  of  veins  about  the  prostate,  neck  of  the  bladder, 
and  rectum,  has  been  described  (p.  529). 

NERVES  OF  Those  which  proceed  from  the  spinal  cord  should 

THE  PELVIS.  be  examined  first,  afterwards  those  derived  from 

the  sympathetic  system. 


544  SACRAL    PLEXUS    OF   NERVES. 

SACRAL  Five  sacral  nerves  proceed  from  the  spinal  cord 

NERVES.  through  the  anterior  sacral  foramina.     The  upper 

four,  from  their  large  size,  at  once  attract  observation ;  but  the 
fifth  is  small :  it  perforates  the  coccygeus  muscle,  supplying  it  and 
the  skin  over  the  coccyx. 

SACRAL  The    anterior    divisions    of  three    upper  sacral 

PLEXUS.  nerves,  and  part  of  the  fourth,  with  the  lumbo- 

sacral  cord,  form  the  sacral  plexus.  The  grea^jnerves  of  this  plexus 
lie  on  the  anterior  surface  of  the  pyriformis,  covered  by  the  pelvic 
fascia,  which  separates  it  from  the  branches  of  the  internal  iliac 
vessels  and  the  pelvic  viscera.  The  large  cords,  diminishing  in 
size  from  above  downwards,  converge  from  the  sacral  foramina 
to  the  great  sacro-sciatic  foramen,  where  they  coalesce  to  form  a 
broad  flat  cord,  which  passes  out  of  the  pelvis  beneath  the  pyri- 
formis muscle,  for  the  supply  of  the  flexor  muscles  of  the  inferior 
extremity. 

Before  describing  the  branches  of  the  sacral  plexus,  it  will  be 
best  to  trace  those  sacral  and  coccygeal  nerves  which  do  not  enter 
into  the  formation  of  the  sacral  plexus. 

The  lower  part  of  the  fourth  sacral  nerve  lies  on  the  coccygeus 
muscle,  and  divides  into  muscular  and  visceral  branches,  sending 
a  filament  downwards  to  join  the  fifth  sacral  nerve.  •  It  distributes 
branches  to  the  pelvic  viscera,  and  muscular  twigs  to  the  levator 
ani,  the  coccygeus,  and  sphincter,  the  latter  of  which  also  furnishes 
a  small  cutaneous  filament  to  the  skin  between  the  bone  and  the 
anus. 

The  fifth  sacral  nerve  emerges  between  the  sacrum  and  the 
coccyx,  pierces  the  coccygeus,  and  lies  on  its  anterior  surface.  It 
is  joined  by  a  twig  from  the  fourth  sacral,  and,  after  running  a 
short  distance,  pierces  the  coccygeus  again,  and  is  distributed  to 
the  skin  over  the  back  of  the  coccyx.  It  communicates  with  the 
coccygeal  nerve,  and  supplies  the  coccygeus  muscle. 

The  coccygeal  nerve,  not  easily  found,  emerges  through  the  end 
of  the  sacral  canal,  and  comes  forwards  through  the  coccygeus,  be- 
tween the  first  and  second  pieces  of  the  coccyx.  It  pierces  the 
great  sacro-sciatic  ligament,  and,  after  receiving  the  communicating 
twig  from  the  fifth  sacral  nerve,  it  passes  backwards  to  supply 


SACRAL   PLEXUS   AND   ITS   BRANCHES. 


545 


the  integument  over  the  back  and  side  of  the  coccyx.  The  com- 
munications between  these  three  last  nerves  are  sometimes  described 
as  the  coccygeal  plexus. 

The  muscular  branches  of  the  sacral  plexus  are  as  follows  : — 
a.  Muscular  branches,  distributed  to  the  pyriformis,  the  gemelli, 
the  quadratus  femoris,  and  the  obturator  internus.     The  nerve  to 


FIG.  131. 


LUMBt 


12.  N.  of  pyriformis. 

13.  N.  of  gemellus  superior. 

14.  N.  of  gemellus  inferior. 

15.  N.  of  quadratus  femoris. 

16.  N.  of  gluteus  maximus. 

17.  Long  pudendal  n. 

18.  Cutaneous  n.  of  the  but- 

tock. 

19.  N.  of  the  long  head  of 

the  biceps. 

20.  N.  of  semi-tendinosus. 

21.  N.    of    semi-membrano- 

sus. 

22.  N.  of  short  head  of  the 

biceps. 


1,  2,  3,  4,  5.  Sacral  nil. 

6.  Superior  gluteal  n. 

7.  Great  sciatic  n. 

8.  Lesser  sciatic  n. 

9.  Pudicn. 

10.  N.  of  obturator  internes. 

11.  N.  of  levator  ani. 


PLAN   OF   THE    SACRAL   PLEXUS   AND    BEANCHES. 

the  obturator  internus  is  given  off  from  the  anterior  aspect  of  the 
plexus  (sometimes  from  the  pudic),  leaves  the  pelvis  through  the 
great  sciatic  foramen  with  the  pudic  artery,  winds  with  it  round 
the  ischial  spine,  and  re-enters  the  pelvis  with  the  artery  to  reach 
the  inner  aspect  of  the  obturator  internus ;  it  distributes  a  small 
twig  to  the  gemellus  superior.  The  branch  to  the  quadratus 
femoris  is  derived  from  the  plexus  near  the  preceding  nerve ;  it 

N  N 


546  SACRAL   PLEXUS   AND   ITS   BRANCHES. 

passes  down,  beneath  the  gemelli  and  obturator  internus,  to  enter 
the  anterior  or  deep  aspect  of  the  quadratus  femoris,  lying  between 
this  muscle  and  the  capsule  of  the  hip-joint :  it  sends  off  a  small 
twig  to  the  inferior  gemellus,  and  another  to  the  hip-joint. 

&.  The  superior  fjluteal  nerve  proceeds  from  the  lumbo-sacral 
cord  and  the  first  sacral  nerve,  leaves  the  pelvis  through  the  great 
sacro-sciatic  foramen  with  the  gluteal  artery,  above  the  pyriformis, 
and  there  divides  into  two  branches  :  the  upper  passes  along  the 
iliac  attachment  of  the  gluteus  minimus,  supplying  it  and  the 
gluteus  medius  ;  the  lower  accompanies  the  lower  branch  of  the 
gluteal  artery,  and  supplies  the  glutei  medius  and  minimus  and 
the  tensor  fasciae  femoris. 

c.  The  pudic  nerve  runs  with  the  pudic  artery,  and  is  contained 
in  the  same  sheath  of  the  obturator  fascia ;  it  divides  into  two 
branches — the  perineal  nerve,  and  the  dorsal  nerve  of  the  penis ; 
the  former  accompanies  the  superficial  perineal  artery,  and  supplies 
cutaneous  branches  and  muscular  branches  to  the  external  sphincter, 
the  accelerator  urinse,  the  transversus  perinei,  the  erector  penis, 
and  the  compressor  urethras  ;  the  dorsal  nerve  accompanies  the  last 
part  of  the  pudic  artery,  and,  after  piercing  the  anterior  layer  of 
the  triangular  ligament  and  the  suspensory  ligament,  runs  along 
the  dorsum  of  the  penis  external  to  the  dorsal  artery,  and  is  dis- 
tributed to  the  glans  and  the  prepuce. 

d.  The  small  sciatic  nerve  is  formed  by  the  junction  of  two 
branches  from  the  sacral  plexus,  and  passes  through  the  great 
sacro-sciatic  foramen  below  the  pyriformis,  and  then  divides  into 
two  branches :  one,  a  motor — the   inferior   gluteal — supplies  the 
gluteus  maximus  ;  the  other,  a  sensory,  supplies  cutaneous  branches 
to  the  back  of  the  thigh  and  leg,  to  the  skin  over  the  gluteus 
maximus,  and  to  the  perineum  and  scrotum.     These  will  be  dis- 
sected later  on  with  the  lower  extremity. 

e.  The  great  sciatic  nerve  is  the  large  nerve-cord  which  passes 
along  the  back  of  the  thigh  beneath  the  gluteus  maximus  and  the 
hamstring  muscles,  and  will  be  dissected  at  a  later  stage. 

PELVIC  SYM-  From  the  lumbar  region  the  sympathetic  nerve 

PATHETIC  PLEXUS,  descends  into  the  pelvis  along  the  inner  side  of 
the  anterior  sacral  foramina.  In  this  part  of  its  course  its  ganglia 


THE  BLADDER,  PROSTATE,  URETHRA,  AND  PENIS.      547 

vary  in  number  from  four  to  five.  The  nerves  of  opposite  sides 
unite  in  front  of  the  coccyx,  where  they  form  the  ganglion  impar. 

The  arrangement  of  the  sympathetic  nerves  in  the  pelvis  is 
similar  to  that  in  the  abdomen,  each  ganglion  receiving  a  branch 
from  the  ganglion  above  and  another  from  the.  ganglion  below. 
The  external  branches  communicate  with  the  sacral  nerves,  one 
probably  going  to,  and  the  other  coming  from,  the  spinal  nerves ; 
the  internal  branches  pass  partly  to  join  the  pelvic  plexus,  and 
partly  to  the  plexus  around  the  arteria  sacra  media. 

The  pelvic  plexuses  are  two  in  number,  and  are  situated  one  011 
each  side  of  the  rectum,  being  derived  from  the  hypogastric  plexus, 
which  passes  downwards  between  the  common  iliac  arteries  into 
the  pelvis,  reinforced  by  filaments  from  the  second,  third,  and  fourth 
sacral  nerves  and  ganglia.  The  visceral  branches  are  exceedingly 
delicate,  and  cannot  be  traced  unless  the  parts  have  been  previously 
hardened  in  spirit.  They  accompany  the  arteries  supplying  the 
respective  organs,  and  are — the  inferior  hcemorrhoidal  plexus  to  the 
rectum ;  the  vesical  plexus  to  the  sides  and  base  of  the  bladder,  and 
secondary  plexuses  to  the  vas  deferens  and  vesicula  seminalis  ;  the 
prostatic  plexus  to  the  prostate,  the  vesicula  seminalis,  and  the 
cavernous  structure  of  the  penis ;  and,  in  the  female,  the  vaginal 
plexus  to  the  vagina  and  its  erectile  tissue,  and  the  uterine  plexus 
to  the  neck  and  lower  part  of  the  body  of  the  uterus,  running 
between  the  layers  of  the  broad  ligament.  It  also  distributes 
numerous  filaments  to  the  fundus  of  the  uterus  and  the  Fallopian 
tubes. 


STEUCTUEE   OF   THE   BLADDEE,   PEG  STATE,   UEETHEA, 
AND   PENIS. 

It  is  assumed  that  the  parts  have  been  collectively  taken  out  of 
the  pelvis,  and  that  the  partial  peritoneal  covering  of  the  bladder 
has  been  removed. 

The  bladder,  in  a  fairly  dilated  condition,  measures  about  five 
inches  in  length  and  three  in  breadth,  and  when  moderately  full 
will  contain  about  a  pint  of  urine. 

N  N   2 


548  STRUCTURE  OF  THE  BLADDER. 

STRUCTURE  OF  The  bladder  is  composed  of  a  partial  peritoneal 

THE  BLADDER.  C0at,    a   muscular,  and  a  mucous ;   between   the 

last  two  there  is  a  layer  of  connective  tissue,  which  is  called  the 
cellular  coat. 

The  serous  or  peritoneal  coat  invests  the  posterior,  lateral,  and 
superior  surfaces  of  the  bladder :  it  is  absent  on  the  anterior  and 
inferior  aspect. 

The  muscular  coat  is  situated  beneath  the  serous,  and  consists 
of  unstriped  muscular  fibres,  which  interlace  with  each  other  in  all 
directions.  Their  general  arrangement  is  as  follows : — An  outer, 
or  longitudinal,  layer  arises  from  the  pubo-prostatic  ligaments,  the 
upper  half  of  the  circumference  of  the  prostate  and  the  neck  of  the 
bladder,  and  thence  its  fibres  spread  out  longitudinally  over  the 
summit  of  the  bladder,  pass  round  its  posterior  aspect  and  base,  to 
be  inserted  into  the  prostate  in  the  male,  and  the  vagina  in  the 
female.  This  layer  is  especially  marked  on  the  anterior  and  pos- 
terior surfaces  of  the  bladder.  There  are  also  some  lateral  longi- 
tudinal fibres  which  pass  backwards  from  the  sides  of  the  prostate 
and  interlace  in  all  directions.  Between  these  is  a  thin  layer  of 
circular  fibres,  especially  developed  near  the  neck  and  the  com- 
mencement of  the  urethra,  where  they  form  a  sphincter — sphincter 
vesicce.  Towards  the  sides  of  the  bladder  the  two  sets  of  fibres 
have  a  less  definite  arrangement  and  form  a  kind  of  network : 
these,  therefore,  are  the  weakest  parts  of  the  bladder,  and  more 
liable  to  the  formation  of  pouches.1  The  development  and  colour 
of  the  muscular  fibres  depend  upon  how  far  the  subject  has  suffered 
from  irritation  of  the  bladder,  or  any  obstruction  to  the  expulsion 
of  the  urine. 

The  cellular  coat  loosely  connects  the  muscular  with  the  mucous 
coat,  and  is  firmly  adherent  to  the  latter. 

1  These  pouches  arise  in  the  following  manner : — A  portion  of  mucous  mem- 
brane is  protruded  through  one  of  the  muscular  interstices,  so  as  to  form  a  little 
sac.  This  is  small  at  first,  but  gradually  increases  in  size,  because,  having  no 
muscular  coat,  it  has  no  power  of  emptying  itself ;  generally  speaking,  several 
such  sacs  are  met  with  in  the  same  bladder  ;  and  they  sometimes  contain  calculi. 
If  a  calculus,  originally  loose  in  the  bladder,  happen  to  become  lodged  in  a  pouch 
by  the  side  of  it,  a  sudden  remission  of  the  symptoms  may  ensue.  This  explains 
our  occasional  inability  to  detect  its  presence  at  each  examination  with  the  sound. 


BLADDER    AND    URETHRA. 
FIG.  132. 


549 


Prostate  gland     .    .  _ 


Membranous  part  of 
the  urethra  .    .    . 


Ureter. 


Orifice  of  ureter. 


Uvula. 

Caput  gallinaginis. 
Orifice  of  seminal 
duct. 

Cowper's  gland. 
Bulb  of  urethra. 
Crus  penis. 

Orifice  of  the  duct  of 
Cowper's  gland. 


One  of  the  lacunae. 


Corpus  cavernosum 
penis. 


Glans  penis. 


BLADDER    AND    URETHRA,    LAID    OPEN    BY    AN    INCISION    ALONG    THE    UPPER    SURFACE. 

*    N   N   3 


550  STRUCTURE  OF  THE  BLADDER. 

The  bladder  must  be  laid  open  by  an  incision  along  its  front, 
to  examine  its  interior.  In  a  recently  contracted  bladder,  the 
mucous  membrane  is  disposed  in  irregular  folds,  which  disappear 
when  the  bladder  is  distended.  In  a  healthy  state,  it  is  pale  ; 
when  inflamed,  it  becomes  of  a  bright  red.  Under  the  microscope, 
its  surface  is  seen  to  be  studded  with  mucous  follicles.  These 
follicles  secrete  the  thick  ropy  mucus  in  inflammation  of  the 
bladder. 

The  mucous  coat  is  loosely  connected  with  the  subjacent  mus- 
cular layer,  except  at  the  trigone  of  the  bladder,  where  it  is  firmly 
adherent.  The  epithelium  is  composed  of  flattened  polyhedral 
cells  of  the  transitional  variety,  and  beneath  these  there  have  been 
described  by  Klein  a  layer  of  large  club-shaped  cells  arranged  at 
right  angles  to  the  surface. 

When  the  interior  of  the  bladder  is  examined,  there  is  seen 
immediately  behind  the  urethra  a  triangular  smooth  surface,  the 
apex  being  at  the  urethra.  This  surface  is  called  the  trigonum 
vesicce,  and  is  paler  and  smoother  than  the  vesical  mucous  mem- 
brane elsewhere ;  laterally,  it  is  bounded  by  ridges  extending  from 
the  urethra  to  the  orifices  of  the  ureters,  the  base  being  between 
the  two  ureters.  This  space  corresponds  with  another  one  already 
described,  external  to  the  bladder,  and  which  is  bounded  laterally 
by  the  vesiculae  seminales,  and  behind  by  the  reflection  of  the 
peritoneum.  It  is  more  richly  provided  with  blood-vessels  and 
nerves  than  the  rest  of  the  bladder,  and  is  endowed  with  more 
acute  sensibility.  This  is  why  a  stone  is  more  painful  when  the 
bladder  is  empty ;  and  in  the  erect,  than  in  the  recumbent  posi- 
tion. 

The  vesical  orifice  of  the  urethra  is  situated  at  the  lower  and 
anterior  part  of  the  bladder,  not  at  the  most  dependent  part,  which 
forms  the  pouch  behind  the  orifice,  in  which  urine  is  apt  to  accu- 
mulate in  old  persons.  It  appears  small  and  contracted  in  the  fresh 
bladder,  but,  if  the  little  finger  be  introduced  into  it,  it  will  dilate 
considerably.  Immediately  behind  the  orifice  there  is,  in  some 
bladders,  a  slight  elevation  called  the  uvula.  It  is  composed  of  a 
portion  of  the  mucous  membrane  raised  up  by  an  accumulation  of 
the  prostatic  and  submucous  tissue,  but  is  rarely  of  sufficient  size 


ARTEKIES  AND  NERVES  OF  THE  BLADDER.         551 

to  interfere  with  the  passage  of  the  urine.  This  elevation  must  be 
distinguished  from  enlargement  of  the  third  or  middle  lobe  of  the 
prostate. 

The  orifices  of  the  ureters  are  situated  about  an  inch  and  a  half 
behind  the  urethra,  and  about  two  inches  apart.  These  tubes  per- 
forate the  coats  of  the  bladder  obliquely,  and  slant  towards  each 
other,  standing  out  in  relief  under  the  mucous  membrane.1  A 
slight  ridge  proceeds  from  the  orifice  of  each  ureter  to  the  neck  of 
the  bladder,  looking  like  a  continuation  of  the  ureter  itself.  If  the 
mucous  membrane  be  removed  from  these  ridges,  we  find  that  they 
are  produced  by  muscular  fibres.  Sir  Charles  Bell,2  who  first  drew 
attention  to  them,  believed  them  to  be  of  use  in  regulating  the 
orifices  of  the  ureters,  and  named  them  the  muscles  of  the  ureters. 

The  bladder  is  supplied  with  blood  by  the  superior,  middle,  and 
inferior  vesical  arteries.  The  superior  conies  from  the  unobliterated 
portion  of  the  hypogastric;  the  middle,  from  the  superior  vesical 
or  the  internal  iliac ;  the  inferior,  from  the  anterior  division  of  the 
internal  iliac  or  the  pudic.  Small  branches  are  also  distributed  to 
the  bladder  by  the  obturator  and  sciatic  arteries. 

The  veins  of  the  bladder  form  large  plexuses  around  its  neck, 
sides,  and  base,  and  empty  themselves  into  the  internal  iliac  veins. 
The  lymphatics  follow  the  course  of  the  veins. 

Its  nerves  are  derived  from  the  hypogastric  and  sacral  plexuses  ; 
the  former  is  chiefly  distributed  to  the  top,  the  latter  to  the  neck 
and  the  bottom  of  the  bladder. 

Having  already  examined  the  form,  size,  and 
PROSTATE 

relations  of  the  prostate  (p.  536),  we  have  now  to 

make  out  its  lobes.     There  are  two  lateral  lobes  presenting  on  their 

1  This  slanting  of  the  ureters  serves  all  the  uses  of  a  valve.     The  urine  enters 
the  bladder,  drop  by  drop,  but  cannot  return,  because  the  internal  coat  is  pressed 
against  the  other  side  of  the  orifice,  so  as  to  stop  it.     When  the  bladder  becomes 
thickened,  in  consequence  of  difficulty  in  passing  urine,  it  sometimes  happens 
that  the  ureters  lose  their  valvular  direction,  so  that  the  urine,  when  the  bladder 
contracts,  is  partly  forced  back  up  the  ureters  :  the  result  is,  that  they  become 
dilated,  and  the  pelvis  of  the  kidney  also. 

2  Med.  Chir.  Trans,  vol.  iii.     He  says :  '  These  muscles  guard  the  orifices  of 
the   ureters   by  preserving  the  obliquity   of  the  passage,   and  pulling  down  the 
extremities  of  the  ureters  according  to  the  degree  of  the  contraction  of  the  bladder 
generally.' 


552  PROSTATE   GLAND. 

upper  and  lower  surfaces  a  median  longitudinal  furrow,  the  lower 
groove  terminating  behind  in  a  deep  cleft ;  and  a  third  or  middle 
lobe.1  The  middle  one  is  pyriform  in  shape,  unites  the  lateral 
lobes,  and  is  situated  between  them  and  the  urethra.  In  health, 
it  does  not  appear  like  a  separate  lobe;  but  when  abnormally 
enlarged,  it  projects  toward  the  cavity  of  the  bladder,  and  acts  like 
a  bar  at  the  mouth  of  the  urethra. 

Make  a  longitudinal  incision  through  the  upper  surface  of  the 
prostate  to  expose  the  urethra.  This  canal  runs  rather  nearer  to 
its  upper  than  its  lower  surface,  and  is  not  of  the  same  calibre 
throughout.  This  part  of  the  urethra  is  about  an  inch  and  a 
quarter  long,  and  about  four  lines  in  diameter.  It  forms  a  sinus 
in  the  interior  of  the  prostate,  described  by  anatomists  as  the  sinus 
of  the  prostate,  into  which  the  ducts  of  the  prostate  open.  Along 
the  floor  of  the  sinus  is  a  longitudinal  ridge,  about  three-quarters 
of  an  inch  in  length,  broad  and  elevated  behind,  but  gradually 
fading  in  front.  This  is  called  the  crest  of  the  urethra,  and  the 
most  prominent  part  of  it  is  named  the  veru  montanum,  or  caput 
gallinaginis,  from  its  supposed  resemblance  to  the  head  of  a  wood- 
cock. On  each  side  of  this  prominence  the  common  ejaculatory 
ducts  open  (p.  549). 

Immediately  in  front  of  the  caput  gallinaginis,  in  the  middle 
line,  is  a  small  opening  which  will  admit  a  probe.  It  leads  back- 
wards into  a  little  cul-de-sac  or  pouch  in  the  substance  of  the 
prostate.  This  pouch  is  described  as  the  analogue  of  the  uterus, 
and  called  the  utriculus  or  sinus  pocularis.  It  is  also  called  the 
uterus  masculimis.  It  is  of  a  pyriform  shape,  running  backwards 
and  upwards  with  the  narrowest  part  at  the  orifice,  and  its  length 
is  about  three  lines.  It  ascends  between  the  lateral  lobes  of  the 

1  Attention  was  first  attracted  to  this  middle  lobe,  in  England,  by  Sir  Everard 
Home,  whose  account  of  it  is  published  in  the  Philos.  Trans,  for  1806.  The  pre- 
paration made  by  Sir  Everard  in  illustration  is  preserved  in  the  Museum  of  the 
Eoyal  College  of  Surgeons  in  London,  Physiol.  Series,  No.  2583  A.  But  the  anatomy 
and  effect  of  the  enlargement  of  this  part  of  the  prostate  gland  is  not  a  discovery 
of  modern  times.  It  was  accurately  described  by  Santorini  in  1739,  and  subse- 
quently by  Camper,  and  is  alluded  to  by  Morgagni  in  the  third  book  of  his  Epistles. 
Dr.  Messer  in  the  43rd  vol.  of  the  Med.  Chir.  Trans,  has  shown  that,  in  subjects 
over  sixty,  the  middle  lobe  is  enlarged  in  20  per  cent. 


PROSTATE   GLAND.  553 

prostate,  and  beneath  the  middle ;  its  coats  are  comparatively 
thick  with  some  muscular  tissue  enclosed  in  them,  and  it  is  lined 
with  squamous  epithelium.  The  minute  orifices  of  the  ducts  are 
seen  opening  into  the  floor  of  the  prostatic  sinus.  The  substance 
of  the  gland  is  permeated  by  the  divisions  and  subdivisions  of  the 
ducts.  They  are  not  visible  to  the  naked  eye,  but  if  traced 
out  with  the  microscope,  they  are  seen  to  terminate  in  blind 
sacculated  extremities,  upon  which  the  capillaries  ramify  in  rich 
profusion.1 

STRUCTURE  OF  The  prostate  is  surrounded  by  a  firm  capsule  of 

THE  PROSTATE.  fibrous  tissue,  and  is  composed  of  muscular  as  well 
as  glandular  tissue.  Nearly  two-thirds  of  it  is  made  up  of  un- 
striped  muscular  fibres,  which  constitute  the  stroma  of  the  gland, 
and  have  the  following  arrangement :  externally,  beneath  the  cap- 
sule, they  form  a  thick  layer,  continuous  behind  with  the  external 
muscular  layer  of  the  bladder ;  and  in  front  they  are  arranged  in  a 
circular  manner  round  the  urethra  at  its  vesical  orifice,  so  as  to 
form  in  conjunction  with  the  vesical  muscular  tissue,  a  sphincter ; 
the  next  layer  forms  a  dense  interlacing  stratum,  in  the  meshes  of 
which  is  found  the  glandular  tissue ;  the  deepest  layer  consists  of 
a  thick  layer  of  circular  fibres,  blending  posteriorly  with  the  in- 
ternal vesical  muscular  layer,  and  continuous  in  front  with  those 
of  the  membranous  part  of  the  urethra.  The  anterior  part  of  the 
prostate  is  chiefly  muscular ;  posteriorly,  the  glandular  elements 
predominate. 

The  glandular  tissue  consists  of  numerous  tubular  alveoli,  which 
open  into  elongated  excretory  ducts  lined  with  columnar  epithelium. 
The  alveoli  are  connected  together  by  connective  tissue,  associated 
with  fibrous  prolongations  from  the  capsule  of  the  gland,  and  with 
the  muscular  tissue.  The  excretory  ducts  are  from  twelve  to 
twenty  in  number,  and  open  into  the  prostatic  sinus  in  the  floor 
of  the  urethra.2  The  prostate  is  remarkable  for  its  dilatability. 

1  This  was  first  demonstrated  by  the  late  Mr.  Quekett.     The  same  anatomist 
has  also  discovered  that  the  secreting  cells  of  the  gland  contain  calculi  of  micro- 
scopic minuteness.     He  finds  them,  almost  without  exception,  in  the  prostate  at 
every  period  of  life.      For  further  detail  concerning  them,  consult  the   article 
'  Prostate '  in  Todd's  Cyclopcedia. 

2  In  the  ducts  of  the  prostate  we  often  find  small  calculi,  of  a  brown  colour, 


554  VESICUL.E   SEMINALES. 

If  a  small  incision  be  made  through  the  anterior  part  of  the  gland, 
the  base  being  left  entire,  the  gland  may  be  dilated  by  the  finger 
sufficiently  to  allow  the  extraction  of  even  large  calculi. 

Any  change  in  the  dimensions  of  the  prostate  affects  the  canal 
which  runs  through  it,  and  more  or  less  obstructs  the  flow  of 
urine.  If  the  entire  gland  be  uniformly  enlarged,  the  length  of 
the  prostatic  urethra  is  increased  ;  if  the  enlargement  preponderate 
at  one  part  more  than  another,  then  the  canal  will  deviate  more  or 
less  from  its  natural  track,  and  assume  a  more  angular  or  a  lateral 
curve  according  to  the  part  enlarged.  When  the  middle  lobe 
becomes  enlarged,  there  arises,  at  the  neck  of  the  bladder,  a  growth 
which  will,  in  proportion  to  its  size,  more  or  less  obstruct  the 
passage  of  the  urine.  In  the  efforts  made  to  introduce  a  catheter 
into  the  bladder,  it  sometimes  happens  that  the  end  of  the  instru- 
ment is  pushed  through  this  hypertrophied  lobe. 

The  prostate  is  supplied  with  arteries  from  the  internal  pudic, 
the  inferior  vesical,  and  the  hoemorrhoidal ;  its  veins  form  a  plexus, 
the  prostatic,  around  the  gland,  receiving  in  front  the  dorsal  vein 
of  the  penis,  and  ending  behind  in  the  internal  iliac  vein:  its 
nerves  are  derived  from  the  hypogastric  plexus,  and  are  inter- 
spersed with  ganglion  cells ;  the  lymphatics  pass  to  the  internal 
iliac  glands. 

VESICUI^E  The  external  appearance  of  these  bodies,  each 

SEMINALES.  of  which  consists  of  a  tube  coiled  upon  itself,  has 

been  already  described  (p.  536).  Respecting  their  structure,  we 
find  that  they  have  an  external  or  connective-tissue  cottt  derived  from 
the  recto-vesical  fascia ;  a  middle  or  muscular,  consisting  of  super- 
ficial fibres  arranged  transversely,  and  of  deep  fibres  arranged 
longitudinally,  and  continuous  with  those  of  the  urethra;  and  an 
internal  or  mucous,  which  is  lined  by  a  scaly  epithelium,  and  pre- 
sents a  honeycombed  structure,  not  unlike  that  of  the  gall-bladder. 
The  duct  emerges  from  the  anterior  part  of  the  vesicula,  and  joins 
at  an  acute  angle  the  vas  deferens  behind  the  prostate,  to  form 
the  common  ejaculatory  duct  (p.  535).  Its  arteries  come  from  the 

consisting  of  phosphate  of  lime.  Cases  are  sometimes  met  with  in  which  these 
calculi  by  degrees  attain  a  considerable  size,  and  distend  the  prostate  into  a  sac, 
which,  when  examined  by  the  rectum,  feels  not  unlike  a  bag  of  marbles. 


THE    URETHRA.  555 

inferior  vesical  and  middle  hsemorrhoidal ;  its  veins  pass  to  the 
internal  iliac  vein,  and  its  nerves  are  derived  from  the  hypo- 
gastric  plexus.  The  function  of  these  bodies  is  twofold — they 
act  as  reservoirs  for  the  semen,  and  secrete  a  fluid  accessory  to 
generation. 

COWPEB'S  The  glands  of  Cowper  have  been  examined  in 

GLANDS.  sifu  in  ^ne  dissection  of  the  perineum  (p.  517). 

They  are  placed  close  to  the  urethra,  one  on  either  side,  imme- 
diately behind  the  bulb  and  between  the  two  layers  of  the  tri- 
angular ligament.  They  consist  of  a  number  of  lobules  united  by 
firm  connective  tissue,  and  their  collective  size  is  somewhat  larger 
than  a  pea.  Each  pours  its  secretion  by  a  minute  duct,  about  an 
inch  long,  into  the  bulbous  part  of  the  urethra.  The  use  of  these 
glands  is  analogous  to  that  of  the  vesiculse  seminales  and  the 
prostate — namely,  to  pour  into  the  urethra  a  fluid  accessory  in 
some  way  to  generation.  They  are  found  in  all  mammalia,  and  in 
some,  e.g.  the  mole,  they  increase  in  size  periodically  with  the 
testicle. 

The  urethra  is  the  canal  which  extends  from 
the  bladder  to  the  end  of  the  penis,  and  serves 
not  only  as  the  outlet  for  the  urine,  but  to  transmit  the  secretion 
of  the  testicles  and  the  several  glands  accessory  to  generation.  It 
varies  in  length  from  eight  to  nine  inches,  and  is  divided  into 
three  portions,  according  to  the  different  structures  by  which  it  is 
surrounded  in  different  parts  of  its  course.  The  first  inch  and  a 
quarter  is  surrounded  by  the  prostate  gland,  and  is  called  the 
prostatic  portion  (p.  530) ;  the  next  three-quarters  of  an  inch 
which  passes  under  the  pubic  arch,  is  surrounded  by  the  com- 
pressor urethrae,  and  is  termed  the  membranous  portion  (p.  530)  ; 
the  remainder  of  its  course,  about  six  inches  in  length,  is  contained 
in  the  corpus  spongiosum,  and  is  called  the  spongy  portion.  The 
length  of  the  urethra  will  vary  much  in  different  subjects,  and 
according  to  the  condition  of  the  penis. 

The  direction  of  the  urethra,  when  the  penis  hangs  flaccid,  is 
like  the  letter  S  reversed;  but  if  the  penis  be  held  straight,  the 
canal  forms  only  one  curve  through  the  pubic  arch,  with  the  con- 
cavity upwards.  The  degree  of  this  curvature  varies  at  different 


556  THE    URETHRA. 

periods  of  life.  In  the  child,  the  bladder  being  more  an  abdominal 
than  a  pelvic  viscus,  the  curve  forms  part  of  a  much  smaller  circle 
than  in  the  adult ;  but  it  gradually  widens  as  age  increases,  and 
catheters  are  shaped  accordingly.1  However,  the  parts,  when  in 
a  sound  state,  will  yield  sufficiently  to  admit  the  introduction  of 
a  straight  instrument  into  the  bladder.  A  straight  staff  is  some- 
times used  in  lithotomy. 

In  its  contracted  state,  the  sides  of  the  urethra  are  in  close 
apposition  ;  the  appearance  it  presents  on  a  transverse  section 
differs  in  the  different  parts  of  its  course.  Through  the  glans 
it  is  flattened  vertically ;  through  the  prostate  it  is  crescentic, 
with  its  convexity  upwards,  owing  to  the  veru  montanum.  But 
throughout  the  rest  of  its  course  the  canal  exhibits  on  section  the 
appearance  of  a  transverse  slit  (fig.  133). 

FIG.  133. 


TRANSVERSE    SECTIONS    OF    THE    URETHRA. 

A.  Through  the  prostate.  B.  Through  the  corpus  spcmgiosum. 

c.  Through  the  glans  penis. 

The  urethra  must  be  laid  open  from  end  to  end  along  its  roof, 
to  see  that  the  canal  is  not  of  uniform  calibre  throughout.  The 
external  orifice  is  the  narrowest  and  the  least  dilatable  part ;  so 
that  the  urine  may  be  expelled  in  a  jet.  Therefore,  any  instru- 
ment which  will  enter  the  meatus  ought  to  pass  into  the  bladder, 
if  there  be  no  stricture.  The  junction  of  the  membranous  with  the 
bulbous  part  is  almost  as  narrow. 

The  prostatic  portion  of  the  urethra  has  been  described  with  the 

1  The  sharper  curve  of  the  urethra  in  the  child  was  well  known  to  Camper. 
'  In  recenter  natis,  vesica  basi  sua  elatius  sita,  pedetentim  descendit,  unde  neces- 
sario  sequitur  curvaturam  urethras  majorem  esse  in  junioribus  quam  in  adultis.' — 
Demon.  Anat.  Patlwl.  lib.  ii.  p.  13. 


THE   URETHRA.  557 

prostate  (p.  552) ;  the  membranous  portion  with  the  anatomy  of 
the  side  view  of  the  pelvic  viscera  (p.  537). 

The. spongy  portion,  so  termed  because  it  is  surrounded  by  the 
erectile  tissue  of  the  corpus  spongiosum,  is  about  six  inches  long. 
That  part  of  it  running  through  the  bulb  is  called  the  bulbous  por- 
tion, and  is  the  most  dilatable  part  of  the  urethra  except  the  pro- 
static.  In  the  centre  of  the  glans  penis  the  canal  widens  into  a 
sinus  termed  fossa  navicularis ;  its  termination,  at  the  meatus 
urinarius,  is  the  most  contracted  part  of  the  urethra. 

The  most  dilatable  part  of  the  urethra  is  the  prostatic.  Even 
the  narrowest  parts  of  the  canal  must  admit  of  considerable  dila- 
tation, since  calculi  of  from  three  to  four  lines  in  diameter  can  pass 
through  it. 

The  common  ejaculatory  ducts  open  into  the  prostatic  part  of 
the  urethra,  by  the  side  of  the  veru  montanum.  The  ducts  of 
Cowper's  glands  open  into  the  bulbous  part.  Besides  these  glands, 
a  number  of  ducts  open  into  the  urethra,  proceeding  from  small 
glands  situated  in  the  submucous  tissue.  These  ducts,  called  the 
glands  ofLittre,  or  lacunae,  are  large  enough  to  admit  a  bristle,  and  run 
in  the  same  direction  as  the  stream  of  the  urine.  Most  of  them  are 
on  the  lower  surface  of  the  urethra ;  but  one,  called  lacuna  macjna, 
is  on  the  upper  surface,  about  one  inch  and  a  half  down  the  canal. 

The  urethra  is  composed  of  three  coats — a  mucous,  muscular, 
and  erectile. 

The  mucous  coat  is  continuous  posteriorly  with  that  of  the 
bladder,  and  it  sends  down  prolongations  into  the  various  ducts 
which  open  into  it.  It  is  arranged  in  longitudinal  folds  in  the 
membranous  and  spongy  portions,  and  is  lined  by  columnar  epithe- 
lium except  near  the  glans,  where  there  are  papilla3,  covered  with 
squamous  epithelium  ;  this,  therefore,  is  the  most  sensitive  part. 

Beneath  the  mucous  membrane  is  a  double  layer  of  unstriped 
muscular  tissue,  the  superficial  fibres  being  arranged  longitudinally, 
the  internal  fibres  circularly.  The  superficial  fibres  are  continuous 
with  those  of  the  bladder,  the  external  fibres  of  which  surround 
the  spongy  portion  of  the  urethra,  being  placed  between  it  and 
its  fibrous  capsule  ;  the  deeper  fibres  of  the  bladder  pass  forwards 
surrounding  the  prostatic  urethra,  and  subsequently  the  spongy 


558  THE   PENIS. 

urethra,  immediately  beneath  the  mucous  membrane.  Between  the 
mucous  and  muscular  coats  is  a  layer  of  areolar  tissue,  the  submucous 
tissue. 

The  erectile  coat,  a  thin  stratum  of  erectile  tissue  derived  from 
the  corpus  spongiosum,  extends  from  this  body  round  the  mem- 
branous and  the  prostatic  portions  of  the  canal. 

Lastly,  the  urethra  is  provided  with  a  closely-set  network  of 
lymphatic  vessels,  which  has  been  demonstrated  by  quicksilver  in- 
jections.1 They  run  from  behind,  forwards,  and  join  the  lymphatics 
of  the  glans  penis.  Eventually,  their  contents  are  transmitted 
down  the  great  trunks  on  the  dorsum  penis  to  the  inguinal  glands. 
This  explains  the  pathology  of  a  bubo. 

The  penis  is  a  pendulous  organ  through  which 
runs  the  urethra,  for  three-fourths  of  its  course  ; 
it  consists  of  a  root,  a  body,  and  the  glans  penis.  The  root  is  the 
broadest  part,  and  is  connected  by  two  crura  to  the  rami  of  the 
pubic  bones ;  its  dorsum  being  supported  by  a  strong  elastic 
suspensory  ligament,  which  is  attached  to  the  symphysis  pubis. 
The  body  is  cylindrical,  consisting  of  the  two  corpora  cavernosa 
and  the  corpus  spongiosum.  The  glans  is  the  expanded  extremity 
which  presents  at  its  apex  the  orifice  of  the  urethra,  and  at  its 
base  where  it  is  attached  to  the  body  there  is  a  deep  circular 
groove,  the  cervix,  the  elevated  margin  in  front  being  called  the 
corona  glandis.  In  these  situations  are  a  number  of  minute 
sebaceous  glands,  glandulce  Tysonii  odoriferce,  which  secrete  a 
sebaceous  substance,  called  srnegma  preputii.  The  surface  of  the 
glans  has  no  sebaceous  glands,  but  is  covered  with  minute  vascular 
papillae,  endowed  with  keen  sensibility  by  the  dorsal  nerves  of  the 
penis.  The  skin  of  the  penis  is  remarkably  thin  and  extensible, 
and  connected  to  the  body  of  the  organ  by  loose  areolar  tissue, 
destitute  of  fat.  At  the  extremity  the  skin  forms  the  prepuce,  or 
foreskin,  for  the  protection  of  the  glans ; 2  and  the  thin  fold  which 

1  Panizza,  Osscrvazioni  antropo-zootom.  &c.,  Pavia,  1830.     This  anatomist  has 
also  displayed  by  injections  an  extremely  fine  network  of  lymphatics  which  covers 
the  glans  penis.     The  interstices  of  this  network  are  smaller  than  the  diameter  of 
the  tubes. 

2  When  the  foreskin  is,  from  birth,  so  tight  that  the  glans  cannot  be  uncovered, 
such  a  state  is  called  a  congenital  phymosis.     This  condition  occasions  no  incon- 


THE   PENIS.  559 

passes  from  the  under  surface  of  the  glans  to  the  prepuce  is  called 
frcenum  preputii.  The  skin,  altered  in  character,  is  reflected  over 
the  glans,  to  which  it  is  intimately  adherent,  and  at  the  orifice  of 
the  urethra  is  continuous  with  the  mucous  membrane. 

The  bulk  of  the  penis  consists  of  two  parallel  cylindrical  bodies, 
of  erectile  structure,  named  from  the  appearance  of  their  interior 
corpora  cavernosa.  In  a  groove  along  their  under  surface  is  lodged  a 
third  cylindrical  body,  the  corpus  spongiosum,  composed  of  vascular 
spongy  tissue,  through  which  runs  the  urethra ;  an  expansion  of 
this  at  the  end  of  the  organ  forms  the  glans.  These  structures, 
then — the  corpora  cavernosa  and  the  corpus  spongiosum — together 
form  the  penis ;  though  the  corpus  spongiosum  appears  closely 
united  t'o  the  corpora  cavernosa,  yet  it  is  quite  distinct  from  them, 
as  shown  in  the  transverse  section  (fig.  134). 

CORPORA  The  corpora  cavernosa,  placed  side  by  side,  con- 

€AVERNOSA.  stitute  more  than  two-thirds  of  the  bulk  of  the 

penis.  Each  commences  posteriorly  by  a  gradually  tapering 
portion,  called  the  cms  penis,  which  is  attached  along  a  groove  in 
the  rami  of  the  ischium  and  os  pubis,  where  it  is  embraced  by  the 
erector  penis  (p.  512).  The  two  crura  converge,  come  into  appo- 
sition at  the  root  of  the  penis,  prior  to  which  each  presents  an 
enlargement,  less  in  man  than  in  some  animals,  called  the  bulb  of 
the  corpus  cavernosum;  they  then  run  together,  side  by  side,  to  form 
the  body  of  the  organ.  Anteriorly,  each  terminates  in  a  rounded 
extremity,  received  into  a  corresponding  depression  in  the  glans, 
to  which  it  is  connected  by  fibrous  tissue. 

A  section  through  the  corpus  cavernosum  shows  that  its  interior 
is  composed  of  a  delicate  reticular  structure,  surrounded  by  a  white 
fibrous  and  elastic  coat,  from  half  a  line  to  a  line  in  thickness,  and 
is  separated  from  its  fellow  by  a  fibrous  septum  called  the  septum 
pectiniforme. 

The  septum  pectiniforme  is  a  median  vertical  partition  between 

venience  in  childhood,  but  is  apt,  after  puberty,  to  become  troublesome  and  painful, 
so  that  it  may  become  necessary  to  slit  up  the  prepuce  and  set  the  glans  at  liberty. 
In  persons  who  have  a  tight  foreskin,  it  sometimes  happens  that,  when  the  glans 
has  been  uncovered,  the  prepuce  cannot  be  again  drawn  over  it :  this  is  called  a 
paraphymosis.  The  neck  of  the  glans  becomes  tightly  girt ;  great  distension  and 
inflammation  are  the  consequences  unless  the  foreskin  be  reduced. 


560 


THE   PENIS. 


the  two  corpora  cavernosa ;  it  is  only  complete  near  the  root  of  the 
penis  ;  along  the  rest  of  the  organ  there  are  vertical  slits  in  it, 
giving  it  the  appearance  of  a  comb :  hence  its  name.  Through 
the  intervals  in  this  partition  the  blood-vessels  of  the  two  corpora 
cavernosa  communicate  freely  with  each  other. 

The  fibrous  investment  is  thick  and  strong,  and  consists  of 
longitudinal  bundles  of  white  fibrous  tissue,  intermingled  with 
yellow  elastic  fibres.  From  the  interior  of  the  fibrous  coat 
numerous  delicate  septa,  trabeculce,  pass  into  the  interior  of  the 
corpus  cavernosum,  intersecting  each  other  in  all  directions,  divid- 
ing it  up  into  a  multitude  of  small  spaces.  This  trabecular  tissue 
consists  of  fibrous  lamellae  with  elastic  and  some  non-striated 


1.  Corpus  cavernosum. 

2.  Corpus  spongiosum 

urethras. 


3,  Dorsal  vein. 

4,  4.  Dorsal  arteries. 

5,  5.  Dorsal  nerves. 


TRANSVERSE    SECTION    THROUGH    THE    PENIS. 


muscular  tissue.  The  spaces,  lined  by  a  layer  of  flattened  epithe- 
lium cells,  similar  to  that  of  veins,  communicate  freely  with  each 
other,  as  may  be  readily  ascertained  by  blowing  air  into  the  penis ; 
they  are  smaller,  and  their  component  septa  thicker  at  the  circum- 
ference than  in  the  centre  of  the  corpora  cavernosa,  at  the  root 
than  towards  the  glans.  Each  corpus  cavernosum  thus  consists  of 
innumerable  spaces  mainly  occupied  by  dilated  venous  sinuses, 
from  which  the  blood  is  conveyed  by  the  dorsal  vein,  the  prostatic 
plexus,  and  the  pudendal  veins.  When  the  penis  is  flaccid,  these 
spaces  are  empty ;  when  it  is  erect,  they  are  distended  with  blood. 
The  arteries  of  the  corpora  cavernosa  come  from  the  branches 
of  the  pudic  (p.  519),  which  enter  the  inner  side  of  each  crus,  at 
its  bulbous  enlargement,  and  proceed  forwards  near  the  septum, 
distributing  numerous  ramifications.  These  are  supported  in  the 


THE    PENIS.  561 

middle  of  the  fibrous  trabeculas,  and  end,  some  in  capillaries  which 
convey  their  blood  at  once  into  the  intertrabecular  spaces  ;  others 
in  tendril-like  prolongations  with  dilated  extremities  which  project 
into  the  spaces,  called  helicine  arteries  by  Miiller,  and  which  open 
directly  into  the  cavities  of  the  veins  by  funnel-shaped  orifices. 
The  helicine  arteries  are  absent  near  the  glans,  and  are  best 
marked  at  the  root  of  the  penis.  The  peculiar  appearance  which 
they  present  when  distended  with  injection  is  due  to  the  fact 
that  they  are  bound  down  to  the  trabecular  tissue  by  fibrous 
bands. 

The  blood  from  the  intertrabecular  spaces  of  the  penis  returns, 
partly  through  veins  which  pass  out  on  the  upper  surface  of  the 
penis  into  the  dorsal  vein  (which  joins  the  prostatic  plexus),  partly 
through  the  deep  veins  which  leave  the  inner  side  of  each  crus,  and 
the  bulb,  to  join  the  internal  iliac. 

CORPUS  The   corpus   spongiosum   is   the   erectile  tissue 

SPONGIOSUM.  which  surrounds  the  urethra  as  it  runs  along  the 

penis.  It  commences  in  the  middle  of  the  perineum,  anterior  to 
the  triangular  ligament,  in  a  bulb-like  form — the  bulb — and  at  the 
end  of  the  penis  it  expands  to  form  the  glans  penis.  It  receives 
posteriorly  an  expansion  from  the  triangular  ligament,  and  presents 
a  median  groove,  marking  its  development  from  two  lateral  halves. 
The  urethra  does  not  pass  through  the  middle  of  the  spongy  body, 
but  runs  nearer  to  its  upper  surface.  The  bulb  hangs  more  or  less 
pendulous  from  the  urethra,  and  is  surrounded  by  the  accelerator 
urinse  muscle  (p.  512).  In  old  persons  it  extends  lower  down 
than  in  children,  and  is,  consequently,  more  exposed  to  injury  in 
lithotomy. 

The  corpus  spongiosum  has  a  fibrous  coat  resembling  very  much 
the  external  fibrous  investment  of  the  corpus  cavernosum,  but  it  is 
thinner,  whiter,  and  composed  of  more  elastic  tissue.  The  reticular 
structure  is  also  finer,  and  the  cavernous  meshes  smaller,  and 
arranged  in  a  longitudinal  direction.  Plain  muscular  fibres  sur- 
round the  urethra,  and  they  are  also  found  in  considerable  amount 
in  the  external  fibrous  coat. 

Its  interior  consists  of  erectile  tissue,  composed  of  a  plexus  of 
minute  tortuous  veins,  lined  by  a  single  layer  of  flattened  endo- 

o  o 


562  THE   FEMALE    PELVIC   VISCERA. 

tlielial  cells,  and  which  communicate  very  freely  with  each  other.. 
This  is  easily  demonstrated  by  injecting  the  dorsal  vein  of  the  penis 
with  wax.  In  this  way,  we  not  only  fill  the  spongy  body,  but  also 
the  glans,  and  the  large  veins  which  form  the  plexus  round  the 
corona  glaiidis. 

The  veins  return  the  blood ;  some  by  small  veins,  which  emerge 
from  the  glans  and  collect  on  the  dorsal  surface  to  form  the  dorsal 
vein ;  others  pass  into  the  dorsal  vein,  either  through  the  corpora 
cavernosa,  or  by  curving  round  the  sides  of  the  corpora  cavernosa  ; 
but  by  far  the  larger  number  join  the  prostatic  and  the  pudic  veins,, 
communicating  also  with  the  subcutaneous  veins  of  the  penis  and 
the  scrotum. 

The  nerves  of  the  penis  are  the  pudic  and  its  superficial  perinea! 
branch.  The  largest  branches  run  along  the  dorsum  to  the  surface 
of  the  glans ;  a  few  only  enter  the  eTectile  tissue  of  the  organ.  The 
pudic  nerve  and  its  branch  supply  the  skin  and  the  mucous  mem- 
brane. Some  of  the  filaments  distributed  to  the  glans  have  con- 
nected with  them  Pacinian  bodies,  and  some  end  in  simple  and 
compound  end-bulbs.  The  erectile  tissue  is  supplied  by  numerous 
filaments  proceeding  from  the  Jiypogastric  plexus. 

The  lymphatics  consist  of  a  superficial  and  a  deep  set ;  the  super- 
ficial, proceeding  from  the  glans  and  the  integument  of  the  penis, 
join  the  inguinal  glands.  The  lymphatics  of  the  glans  communicate 
freely  all  round  it :  this  explains  why  a  venereal  sore  on  one  side 
sometimes  affects  the  inguinal  glands  on  the  other.  The  deep 
lymphatics  from  the  corpora  cavernosa  and  the  corpus  spongiosum 
pass  beneath  the  pubic  arch  and  join  the  lymphatics  of  the  pelvis. 


DISSECTION   OF  THE  FEMALE   PELVIC  VISCEKA. 

SIDE  VIEW  OF  After  the  removal  of  the  left  innominate  bone, 

THE  FEMALE  as  described  in  the  dissection  for  the  side  view  of 

PELVIC  ORGANS.  ^Q  male  pelvic  viscera,  the  vagina,  rectum,  and 
bladder  should  be  moderately  distended,  the  two  former  with  tow, 
the  latter  with  air.  This  done,  the  reflections  of  the  peritoneum 
must  be  traced,  the  description  of  which  will  be  found  in  the  dis- 


THE    URETHRA.  563 

section  of  pelvic  viscera  from  above  (fig.  117).     After  this,  clean  off 
the  peritoneum,  and  make  out  the  pelvic  fascia  and  its  prolongations. 
To  the  description  of  the  fascia  already  given  in 
the  dissection  of  the  male  pelvis  (p.  528)  nothing 
need  be  added,  except  that  from  the  side  of  the  pelvis  it  is  re- 
flected over  the  side  of  the  .vagina  and  the  uterus,  as  well  as  the 
bladder. 

It  is  this  fascia  which  in  great  measure  supports  the  uterus  in 
its  proper  level  in  the  pelvis.  When,  from  any  cause,  the  fascia 
becomes  relaxed,  there  is  a  liability  to  prolapsus  uteri. 

LEVATOR  ANI.  For  the  description  of  this  muscle,  see  p.  538. 

The  female  bladder  is  broader  transversely,  and, 
upon  the  whole,  more  capacious  than  the  male. 
The  vesical  plexus  of  veins  is  not  so  large,  and  there  are  no  vasa 
deferentia  or  prostate  gland.  The  short  urethra  has  a  constrictor 
muscle,  as  in  the  male,  and  is  supported  in  a  similar  manner  by 
the  pelvic  fascia. 

yENOUS  Though  the  veins  round  the  neck  of  the  bladder 

PLEXUS  ABOUT  are  comparatively  small  in  the  female,  attention 

THE  VAGINA.  should  be  directed  to  the  plexus  of  large  veins 

which  surround  the  vagina.  They  communicate  freely  with  the 
veins  about  the  rectum,  and  empty  themselves  into  the  internal 
iliac.  Their  congestion  in  pregnancy  sufficiently  accounts  for  the 
dark  colour  of  the  vagina  and  the  external  organs,  and  the  frequent 
occurrence  of  haemorrhoidal  tumours.1  These  veins  must  be  re- 
moved, with  the  connective  tissue  in  which  they  are  embedded, 
before  a  clear  view  of  the  parts  can  be  obtained. 

The  urethra  has  already  been  described  (p.  523). 
UEETHEA  ... 

But,  in  the  side  view  of  the  parts,  we  have  the 

opportunity  of  observing  how  closely  the  bladder  and  urethra  are 
connected  to  the  upper  wall  of  the  vagina  ;  and  we  can  understand 
how,  in  cases  of  protracted  delivery,  it  sometimes  happens  that  the 
contiguous  coats  of  the  bladder  and  the  vagina  give  way,  and  that 

1  During  pregnancy,  varicose  tumours  may  form  even  in  the  vagina.  In  the 
Berlin  Med,  Zeitung,  1840,  No  11,  a  case  is  related  of  a  woman  who,  at  the  sixth 
month,  bled  to  death  from  the  bursting  of  a  large  vein  in  the  vagina.  Other  cases 
of  the  kind  are  related  by  Siebold. 

o  o  2 


564  THE   VAGINA. 

a  fistulous  communication  remains  between  them,  through  which 
urine  constantly  dribbles. 

It  is  necessary  to  slit  open  the  whole  of  the 
vagina  along  the  side,  to  obtain  a  clear  idea  of  the 
manner  in  which  it  embraces  the  lower  end  of  the  uterus,  and  of 
the  extent  to  which  the  neck  of  the  uterus  projects  into  it. 

The  length  of  the  vagina,  in  the  unimpregnated  adult,  is,  on  an 
average,  about  four  inches  on  its  anterior  wall,  and  between  five 
and  six  along  its  posterior  wall,  owing  to  its  curved  direction.  It 
may  be  more,  or  less  ;  the  difference  in  each  case  depending  upon 
the  depth  of  the  pelvis,  the  stature  and  age  of  the  individual.  The 
vagina,  however,  is  never  so  long  that  we  cannot,  during  life,  feel 
the  neck  of  the  uterus  projecting  at  the  top  of  it,  higher  up,  or 
lower  down,  according  to  circumstances.  For  instance,  it  is  a  little 
lower  down  in  the  erect  than  in  the  recumbent  position ;  again,  in 
the  early  months  of  utero-gestation,  the  uterus  descends  a  little 
into  the  vagina,  so  that  this  canal  becomes  shorter :  the  reverse 
holds  good  when  the  uterus  begins  to  rise  out  of  the  pelvis. 

The  axis  of  the  vagina  is  slightly  curved  with  the  concavity 
upwards ;  it  corresponds  with  the  axis  of  the  outlet  of  the  pelvis. 

The  width  of  the  vagina  is  not  uniform  throughout.  The 
narrowest  part  is  at  the  orifice ;  it  is  also  a  little  constricted  round 
the  neck  of  the  uterus.  The  widest  part  is  about  the  middle : 
here  a  transverse  section  through  it  presents  the  appearance  of  a 
broad  horizontal  fissure.  If,  therefore,  you  would  insert  the  bivalve 
speculum  with  the  least  amount  of  pain,  the  blades  of  the  speculum 
should  be  vertical  when  introduced  into  the  orifice,  and  afterwards 
turned  horizontally. 

STRUCTURE  OF  The   vagina   consists   of  a  mucous  coat,  of  a 

THE  VAGINA.  muscular  coat,  and  of  an  external  coat  of  erectile 

tissue. 

The  mucous  membrane  is  of  a  pale  rose  colour,  continuous  above 
with  that  of  the  uterus,  and  below  with  the  integument  of  the  labia 
majora.  It  is  rough  and  furrowed,  especially  near  the  orifice,  and 
it  presents  two  longitudinal  ridges — columnce  rugarum — which  run, 
one  along  the  anterior,  the  other  along  the  posterior  wall.  From 
each  side  of  these  proceed  a  series  of  transverse  ridges — rugae — 


THE   UTERUS.  565 

with  rough  margins  directed  forwards.  They  are  well-marked  in 
virgins,  but  repeated  parturition  and  increasing  age  gradually 
smooth  them  down.  The  use  of  the  vaginal  rugge  is  to  excite  the 
sensibility  of  the  glans  in  coition.  They  themselves  alsd  possess 
keen  sensibility,  being  richly  endowed  with  papillae.  The  mucous 
membrane  is  provided  with  numerous  papillae,  conical  in  shape, 
and  covered  with  a  thick  lining  of  squamous  epithelium.  In  the 
subrnucous  tissue,  which  is  very  loose,  there  is  a  good  deal  of  mus- 
cular tissue,  with  a  considerable  venous  plexus,  forming  a  kind  of 
erectile  tissue  ;  in  it,  also,  are  found  an  abundant  supply  of  muci- 
parous  glands,  which  increase  in  size  and  number  towards  the  uterus. 

The  muscular  coat  is  arranged  in  two  layers,  a  longitudinal  and 
a  circular,  between  which  there  may  be  demonstrated  a  number  of 
interlacing  fibres  passing  from  one  to  the  other  layer.  The  longi- 
tudinal fibres  are  continuous  with  the  superficial  muscular  fibres  of 
the  uterus,  while  the  latter  are  chiefly  aggregated  at  the  orifice  of 
the  vagina,  forming  a  kind  of  sphincter  muscle,  which  is  continuous 
with  the  external  sphincter  ani.  Superiorly,  the  vagina  is  inti- 
mately attached  to  the  neck  of  the  uterus,  while  to  the  rectum  it  is 
but  loosely  connected. 

The  erectile  tissue  found  in  the  connective  tissue  forms  the  chief 
strength  of  the  vagina,  being  about  one-twelfth  of  an  inch  in  thick- 
ness. If  this  coat  be  minutely  injected,  we  find  that  it  is  composed 
mainly  of  a  plexus  of  veins  surrounded  with  numerous  fasciculi  of 
unstriped  muscular  fibres. 

The  uterus  is  the  hollow  muscular  organ  which 
UTEKUS.  .  . 

receives  the  ovum,  retains  it  for  nine  months  to 

bring  it  to  maturity,  and  then  expels  it  by  virtue  of  its  muscular 
walls.  Its  situation  and  peritoneal  connections  have  been  described 
(p.  503).  Its  axis  slants  forwards,  so  that,  upon  the  whole,  the 
axis  of  the  vagina  and  uterus  describes  a  curve  nearly  parallel  to 
the  axis  of  the  pelvis.  The  uterus,  then,  is  so  situated  that  it  is 
ready  to  rise  out  of  the  pelvis  into  the  abdomen  after  the  embryo 
has  attained  a  certain  size. 

The  uterus  in  the  unimpregnated  state  is  pyriform,  or  rather  tri- 
angular with  the  angles  rounded,  and  is  somewhat  flattened  antero- 
posteriorly.  It  is  retained  in  its  position  by  the  broad  and  round 


566  THE    UTERUS. 

ligaments,  and  measures  about  three  inches  in  length,  two  in  its 
broadest  part,  and  one  inch  thick  in  its  upper  part,  and  weighs  from 
an  ounce  to  an  ounce  and  a  half;  but  there  is  a  variety  in  this 
respect,  arising  from  age,  the  effect  of  pregnancy,  and  other  causes. 

For  convenience  of  description  the  uterus  is  divided  into  the 
fundus,  the  body,  and  the  cervix. 

The  fundus  is  applied  to  the  broadest  part,  which  lies  above 
the  level  of  the  Fallopian  tubes,  and  is  completely  invested  by 
peritoneum. 

The  body  is  the  central  part,  and  gradually  narrows  down  to  the 
cervix.  Its  lateral  margins  are  nearly  straight,  and  give  attach- 
ment, respectively  from  above  downwards,  to  the  Fallopian  tube,  the 
round  ligament,  the  ligament  of  the  ovary,  and  the  broad  ligament ; 
its  anterior  surface  is  flat,  and  for  full  three-fourths  of  its  extent 
is  covered  with  peritoneum  ;  its  posterior  surface  is  convex,  and  is 
entirely  invested  with  peritoneum. 

The  cervix  is  the  lower  narrow  part  which  projects  into  the 
vagina.  The  vagina  is  very  closely  attached  round  the  neck  of  the 
uterus ;  observe  that  it  is  attached  higher  up  behind  than  in  front. 
At  the  free  end  of  the  cervix  there  is  a  transverse  slit,  the  os  uteri, 
bounded  in  front  by  the  anterior  lip,  behind  by  the  posterior  lip. 

Postponing  for  the  present  the  examination  of  the  interior  of 
the  vagina  and  the  uterus,  let  us  pass  on  to  the  vessels  and  nerves 
of  these  organs. 

UTERINE  AND  The  uterus  is  supplied  by  the  uterine  arteries 

VAGINAL  AKTEEIES.    derived  from  the  internal  iliac,  and  also  by  the 
ovarian  arteries  ;  the  vagina  by  the  vaginal  arteries  from  the  same  • 
source  ;  and  the  ovaries  by  the  ovarian  arteries  (which  correspond 
to  the  spermatic  arteries  in  the  male)  given  off  from  the  abdominal 
aorta  just  below  the  renal  arteries. 

The  uterine  artery  proceeds  from  the  anterior  division  of  the 
internal  iliac,  towards  the  neck  of  the  uterus,  between  the  layers 
of  the  broad  ligament,  and  then  ascends  tortuously  by  the  side  of 
the  uterus,  giving  off  numerous  branches  to  it,  which  anastomose 
freely  with  each  other,  and  with  a  small  branch  from  the  ovarian 
artery.  The  fundus  of  the  uterus  is  mainly  supplied  with  branches 
from  the  ovarian  arteries. 


STRUCTURE  OF  THE  UTERUS.  567 

The  vaginal  artery  ramifies  along  the  side  of  the  vagina,  and 
distributes  branches  to  the  lower  part  of  the  bladder  and  the 
rectum. 

The  veins,  of  large  size,  corresponding  with  the  arteries,  form 
the  uterine  sinuses  and  the  vaginal  plexuses,  which  empty  them- 
selves into  the  internal  iliac  vein. 

NEKVKS  OF  THE          The  nerves  of  the  uterus  are  derived  from  the 
UTEBUS.  third  and  fourth  sacral  nerves,  from  the  hypogastric 

and  ovarian  plexuses  (p.  495).  They  accompany  the  blood-vessels 
in  the  broad  ligament  to  the  neck  of  the  uterus,  and  ascend  with 
them  along  its  sides. 

Some  small  filaments  continue  with  the  vessels,  and  form  around 
them  plexuses,  upon  which  minute  ganglia  are  found.1  But  most 
of  the  nerves  soon  leave  the  vessels,  and,  subdividing,  sink  into  the 
substance  of  the  uterus,  chiefly  about  its  neck  and  the  lower  part  of 
its  body.  A  branch  may  be  traced  passing  up  to  the  fundus  of  the 
uterus,  and  another  to  the  Fallopian  tube. 

The  nerves  of  the  uterus  enlarge  during  pregnancy  like  the 
arteries.  Surgically  speaking,  the  os  uteri  may  be  said  to  have  no 
nerves ;  for  it  is  insensible  to  the  cautery  and  to  the  knife. 

The  lymphatics  of  the  uterus  are  small  in  its  unimpregnated 
•state,  but  greatly  increase  in  size  when  it  is  gravid.  Those  from 
the  fundus  and  the  ovaries  proceed  with  the  ovarian  vessels  to  the 
lumbar  glands ;  thus  explaining  the  affection  of  these  glands  in 
•ovarian  diseases.  Those  from  the  body  and  the  lower  part  of  the 
uterus  accompany  the  uterine  arteries,  and  join  the  glands  in  the 
pelvis ;  some,  however,  run  with  the  round  ligament  to  the  groin  ; 
hence,  in  certain  conditions  of  the  uterus  the  inguinal  glands  may 
be  affected. 

The  uterus,  vagina,  Fallopian  tubes,  and  the  ovaries  should 
now  be  collectively  removed  from  the  pelvis  for  the  purpose  of 
examining  their  internal  structure. 

The  structure  of  the  vagina  has  been  already  described  (p.  564). 

STRUCTUKE  OF  Before  the   uterus  is  laid  open,   examine  the 

THE  UTERUS.  shape  of  that  portion  of  the  neck  which  projects 

into  the  vagina.     The  back  part  of  the  cervix  appears  to  project 

1  Beck,  Philosophical  Transactions  for  1846. 


568  STRUCTURE  OF  THE  UTERUS. 

into  the  vagina  more  than  the  front;  but  this  arises  from  the 
vagina  being  attached  higher  up  posteriorly.  If  the  vagina  were 
cut  away  from  the  cervix,  the  anterior  lip  of  the  uterus  would 
appear  to  project  a  trifle  more  than  the  posterior.  For  thi& 
reason,  as  well  as  on  account  of  the  natural  slope  forwards  of  the 
uterus,  the  front  lip  is  felt  first  in  an  examination  per  vaginam.1 
The  length,  however,  and  the  general  appearance  of  the  vaginal 
part  of  the  cervix  vary  according  to  the  age ;  it  is  also  consider- 
ably altered  by  parturition.  In  the  adult  virgin  it  is  smooth  and 
round,  and  projects  about  half  an  inch;  its  mouth  is  a  small 
transverse  fissure.  But  after  parturition  it  loses  its  plumpness, 
the  lips  become  flaccid  and  fissured,  and  the  mouth  larger  than  it 
was  before.2 

The  uterus  must  now  be  laid  open  by  a  longitudinal  incision, 
to  examine  its  interior.  In  doing  so,  observe  the  thickness  of  its 
walls,  which  is  greatest  towards  the  fundus.  Before  coming  into 
the  proper  cavity  in  the  body  of  the  uterus,  slit  up  a  long  narrow 
canal  which  leads  up  into  it  through  the  neck.  This  canal,  which 
is  about  an  inch  in  length,  is  not  of  the  same  dimensions  through- 
out :  it  is  dilated  in  the  middle,  and  gradually  narrows  towards 
each  end.  The  upper  end  which  leads  into  the  body  of  the  uterus,, 
is  called  os  internum ;  the  lower  end,  which  leads  into  the  vagina, 
os  externum.  The  passage  is  called  the  canal  of  the  cervix.  It 

O  «/ 

remains  unchanged  in  pregnancy  for  some  time  after  the  cavity  in 
the  body  has  expanded,  but  gradually  disappears  with  the  increas- 
ing size  of  the  embryo. 

The  shape  of  the  cavity  in  the  body  of  the  uterus  is  triangular, 

1  This  is  the  only  way  to   reconcile   the   discrepancies   one   meets   with  in 
anatomical  works,  respecting  the  comparative  length  of  the  lips  of  the  uterus. 
Krause,  Weber,  Busch,  and  others,  say  the  anterior  is  the  longer  ;  Mayer,  Meckel, 
Quain,  and  others,  the  posterior. 

2  Instances  are  recorded  in  which  the  neck  of  the  uterus  is  preternaturally  long. 
It  has  been  known  to  project  even  as  much  as  an  inch  and  a  half  into  the  vagina. 
In  such  cases  it  gradually  tapers,  and  terminates  in  a  very  narrow  mouth.     This 
is  said  to  be  one  cause  of  sterility,  and  it  is  recommended  either  to  dilate  the 
mouth,  or  to  cut  off  a  portion  of  the  neck.     In  support  of  this  opinion,  it  is  stated 
that  Dupuytren  was  once  consulted  by  a  lady  on  account  of  barrenness :  finding 
the  neck  of  the  uterus  unusually  elongated,  he  removed  a  portion  of  it,  and  shortly 
the  lady  became  pregnant.     (Hyrtl,  Handbuch  der  top.  Anatom.) 


STRUCTURE  OF  THE  UTERUS.  569 

with  the  apex  towards  the  cervix.  In  a  virgin  uterus  the  cavity 
is  very  small,  and  its  sides  are  convex ;  but  in  a  uterus  which  has 
borne  many  children,  the  cavity  has  lost  the  convexity  of  its  sides, 
and  has  increased  in  capacity.  Each  angle  at  the  base  is  some- 
what prolonged,  and  leads  to  the  minute  opening  of  the  Fallopian 
tube.  This  prolongation  of  the  angles  is  noticed  more  or  less  in 
different  females,  and  is  the  last  indication  of  the  two  horns  of  the 
uterus  in  some  orders  of  mammalia. 

The  interior  of  the  uterus  is  smooth  at  the  fundus;  but  the 
reverse  at  the  cervix.  Here  there  is  a  central  longitudinal  ridge, 
both  in  front  and  behind  (as  in  the  vagina)  ;  from  these,  other 
closely  set  oblique  ridges  curve  off  laterally,  like  the  branches  of  a 
palm-tree,  called  arbor  vitce  uterina.  The  roughness  produced  by 
these  ridges  occasions  an  impression  as  though  we  were  touching 
cartilage  when  a  sound  is  introduced  into  the  uterus. 

The  neck  of  the  uterus  is  provided  with  small  muciparous 
glands,  of  which  the  minute  ducts  open  in  the  furrows  between 
the  ridges  referred  to.  The  secretion  of  these  glands  is  glairy, 
albuminous,  and  slightly  alkaline.  Soon  after  impregnation,  the 
secretion  becomes  so  firm  as  to  plug  the  mouth  of  the  uterus,  but 
shortly  before  and  during  parturition  it  is  poured  out  in  great 
quantity,  to  facilitate  the  passage  of  the  child.  It  happens  occa- 
sionally that  one  or  more  of  the  ducts  of  these  glands  becomes 
obstructed,  and  then  dilate  into  small  transparent  vesicles,  which 
gradually  rise  to  the  surface  and  burst.1 

The  walls  of  the  uterus  consist  of  an  outer  serous  coat  derived 
from  the  peritoneum,  an  inner  mucous  lining,  and  an  intermediate 
layer  of  unstriped  muscular  tissue. 

The  serous  coat  has  been  already  described. 

The  muscular  coat  forms  the  greater  part  of  the  thickness  of 
the  walls  of  the  uterus,  and  consists  of  non-striped  or  involuntary 
muscular  fibres,  chiefly  aggregated  at  the  fundus,  less  so  at  the 
junction  of  the  Fallopian  tubes.  The  texture  of  these  fibres  is 
very  close,  and  interwoven  together  with  blood-vessels,  nerves, 
lymphatics,  and  connective  tissue ;  so  that  in  the  unimpregiiated 

1  These  were  first  described  by  Naboth,  and  supposed  to  be  true  ova  :  hence 
their  name,  ovula  Nabothi.     (De  Sterilitate  Mulierum.    Lips.,  1707.) 


570  STRUCTURE  OF  THE  UTERUS. 

uterus  it  is  almost  impossible  to  trace  thein.t  In  the  impregnated 
condition  it  is  less  difficult  to  trace  them,  and  we  can  make  out 
that  the  fibres  are  arranged  in  three  layers — an  external,  a  middle, 
and  an  internal.1 

The  external  layer,  placed  immediately  beneath  the  peritoneum, 
is  thin,  and  its  fibres,  beginning  as  longitudinal  at  the  cervix,  run 
transversely  round  the  uterus,  some  of  them  being  continued  in  an 
oblique  direction  over  the  body  into  the  broad  ligaments ;  these 
are  continued  on  to  the  Fallopian  tubes,  the  round  ligaments,  and 
the  ligaments  of  the  ovaries.  A  band  of  longitudinal  fibres  passes 
from  the  anterior  surface  of  the  uterus  round  the  fundus  to  its 
posterior  aspect,  beneath  the  recto-uterine  folds  of  the  peritoneum. 

The  middle  layer  runs  in  all  directions,  having  no  definite 
arrangement  of  its  fibres. 

The  internal  layer  is  composed  mainly  of  concentric  circles 
which  surround  the  orifices  of  the  Fallopian  tubes ;  .at  the  cervix 
its  fibres  are  arranged  transversely,  forming  a  sphincter.  It  is  this 
layer  which  forms  the  thickest  stratum  and  is  closely  connected 
with  the  mucous  membrane ;  it  is  called  the  muscularis  mucosa. 

Upon  the  whole,  the  collective  disposition  of  the  muscular 
layers  is  such  as  to  exert  equal  pressure  on  all  sides,  when  called 
into  action.  At  the  same  time  that  they  expel  the  foetus,  the 
muscular  fibres  perform  another  very  important  function :  they 
close  the  large  venous  sinuses  consequent  upon  the  great  increase 
in  the  amount  of  blood  during  pregnancy.  Therefore,  little  haemor- 
rhage accompanies  the  expulsion  of  the  placenta,  provided  it  have 
been  attached  to  the  fundus  or  the  side  of  the  uterus.  But  every- 
one knows  the  danger  of  what  is  called  'placenta  prcevia.  Here, 
the  placenta,  placed  entirely  or  partly  over  the  orifice  of  the  uterus, 
is  attached  to  a  part  of  the  organ  which  must  of  necessity  expand 
during  labour ;  and  every  uterine  contraction  increases,  instead  of 
checking,  the  bleeding.  For  the  same  reason,  paralysis  of  the 
muscular  fibres  in  immediate  connection  with  the  placenta,  be  it 
where  it  may,  is  likely  to  be  a  source  of  serious  haemorrhage  in 
parturition. 

1  In  the  unimpregnated  uterus  the  muscular  fibres  are  about  Tj5th  of  an  inch 
in  length  ;  in  the  gravid  uterus  they  increase  to  ^th  of  an  inch. 


FALLOPIAN   TUBES. 


571 


The  mucous  membrane  of  the  uterus  is  more  delicate  and 
softer  than  that  of  the  vagina,  with  which  it  is  continuous,  and 
is  closely  united  to  the  subjacent  tissue.  The  greater  part  of  it 
is  lined  by  a  columnar  ciliated  epithelium,  but  that  which  lines 
the  lower  part  of  the  cervix  is  squamous,  like  that  of  the  vagina. 
Examined  with  a  lens,  the  mucous  membrane  lining  the  body  of 
the  uterus  is  seen  to  be  covered  with  minute  follicles  or  tubes 
(uterine  glands)  arranged  at  right  angles  to  its  surface.  These 
tubes  pass  outwards  in  a  more  or  less  spiral  manner,  some  of  them 
appearing  branched  and  dilated  at  their  extremities.  They  become 
greatly  developed  shortly  after  impregnation,  and  take  an  impor- 
tant part  in  the  formation  of  the  membrana  decidua. 

The  arrangement  of  the  mucous  membrane  in  the  cervix  has 
been  already  described  (p.  569),  when  the  uterus  was  laid  open  to 
expose  its  cavity. 

FALLOPIAN  The  Fallopian  tiibes  or  oviducts  are  situated,  one 

TUBES.  on  each  side,  along  the  upper  free  border  of,  and 

enclosed  by,  the  broad  ligament  of  the  uterus,  and  convey  the  ovum 

FIG.  135. 


DIAGRAM  OF  THE  UTERUS,  ITS  BKOAD  LIGAMENTS,  THE  OVABIES  AND  FALLOPIAN 
TUBES.     (SEEN  FROM  BEHIND.) 


1.  Uterus. 

2.  Ovary,  with  its  ligaments. 

3.  Fallopian  tube. 


4.  Fimbriated  extremity  of  Fallopian  tube. 

5.  5.  Broad  ligament. 

6.  Vagina. 


from  the  ovary  to  the  uterus  (fig.  135).  They  are  about  four 
inches  in  length  :  one  end,  the  ostium  internum,  opens  by  a  minute 
orifice  into  the  upper  angle  of  the  cavity  of  the  uterus ;  the  other 


572  THE    OVARIES. 

terminates  in  a  wide,  funnel-shaped  mouth,  the  ostium  abdominale, 
surrounded  by  fringe-like  processes  called  the  fimbrice.  This  ter- 
mination of  the  Fallopian  tube  is  called  its  fimbriated  extremity,1 
and  its  canal  opens  into  the  peritoneal  cavity,  so  that  thus  the 
cavity  of  the  peritoneum  in  the  female  communicates  through 
the  uterus  and  the  vagina  indirectly  with  the  exterior.  The  fim- 
briated extremity  extends  about  an  inch  beyond  the  ovary,  and,  by 
floating  it  in  water,  one  or  two  of  the  fimbriee  may  be  seen  con- 
nected with  the  outer  end  of  the  ovary.  If  the  Fallopian  tube  be 
opened  from  the  dilated  end,  and  a  probe  introduced  into  it,  you 
will  find  that  the  tube  runs  very  tortuously  at  first,  then  straight 
into  the  uterus,  gradually  contracting  in  size,  so  that  the  uterine 
orifice  scarcely  admits  a  bristle.  The  free  end  of  the  tube  com- 
municates with  the  cavity  of  the  peritoneum.  This  is  the  only 
instance  where  a  mucous  membrane  is  directly  continuous  with  a 
serous  one.  It  explains  how  the  embryo  may  escape  into  the 
peritoneal  cavity ;  though  this  is  an  extremely  rare  occurrence. 
It  also  explains  what  is  said  to  have  occurred  :  namely,  the  escape 
of  the  fluid  in  dropsy  through  the  Fallopian  tubes.  In  a  well- 
injected  subject,  the  Fallopian  tubes  are  seen  to  be  well  supplied 
with  blood  from  the  ovarian  arteries.  The  coats  of  the  Fallopian 
tube  are  three — an  external  serous  coat  derived  from  the  perito- 
neum ;  a  middle  muscular  coat,  consisting  of  plain  muscular  fibres ; 
an  external  layer,  longitudinal,  and  an  internal  layer,  circular,  both 
being  continuous  with  •  those  of  the  uterus ;  and  an  internal  mucous 
coat  arranged  in  longitudinal  folds,  especially  at  the  ovarian  end, 
and  covered  with  a  columnar  ciliated  epithelium. 

The  ovaries  (called  by  Galen,  testes  muliebres, 
being  the  analogues  of  the  testes  in  the  male)  are 
two  oval  bodies  situated  between  the  two  layers  of  the  broad  liga- 
ment of  the  uterus,  in  its  posterior  part.  They  are  connected  on 
their  inner  side  to  the  uterus  by  a  thin  cord,  called  the  ligament  of 
the  ovary,  and  at  their  outer  end  they  are  usually  attached  to  one 
of  the  fimbrise  of  the  Fallopian  tube  by  fibrous  tissue.  The  ovaries 
are  of  whitish  colour,  with  the  long  axis  transverse,  flattened  from 

1  The  fimbriated   extremity  is  sometimes  called  the  morsus  diaboli,  since  it 
embraces  in  a  peculiar  way  the  ovary  during  sexual  excitement. 


STRUCTURE   OF   THE   OVARIES.  573 

above  downwards,  and  in  females  who  have  not  often  menstruated, 
their  surface  is  smooth  and  even ;  in  after-life,  they  become 
puckered  and  scarred  by  the  repeated  escape  of  the  ova. 

The  position  of  the  ovaries  is  described  by  Professor  His  as 
being  nearly  vertical,  and  he  states  that  the  Fallopian  tube  curves 
round  the  outer  to  the  lower  border  of  the  ovary,  so  that  the 
fimbriated  extremity  lies  beneath  the  ovary,  with  its  fimbrise 
directed  upwards  ;  thus  the  ova  on  their  escape  from  the  ovary  fall 
into  the  Fallopian  tube.1 

The  ovary  is  about  an  inch  and  a  half  long,  three-quarters  of  an 
inch  wide,  and  about  half  an  inch  thick ;  its  weight  being  from 
one  to  two  drachms.  It  consists  of  a  dense  soft  stroma,  imbedded 
in  which  are  numerous  small  vesicles  (Graqfian  vesicles'),  muscular 
tissue,  blood-vessels  and  nerves,  the  organ  being  invested  by  a 
serous  covering. 

The  serous  layer  covers  the  ovary,  but  does  not  present  the 
ordinary  features  of  a  peritoneal  investment,  for  the  covering  is 
dull  and  not  shining,  and  the  epithelium  consists  of  a  single  layer 
of  columnar  cells  which  are  the  remains  of  the  germ  epithelium, 
from  which  the  ova  and  the  other  cells  in  the  Graafian  vesicles 
have  been  originally  developed.2 

The  stroma  composes  the  substance  of  the  ovary,  and  consists 
of  some  connective  tissue  associated  with  a  large  amount  of  spindle- 
shaped  cells,  resembling  in  their  appearance  unstriped  muscle-cells. 
It  contains  also  elastic  tissue,  and  is  abundantly  supplied  with 
blood-vessels,  which  are  larger  at  the  hilum  of  the  ovary,  diminish- 
ing in  size  towards  its  surface.  The  outer  part  of  the  stroma  is 
much  condensed,  so  as  to  give  a  white  appearance  to  the  organ ; 
this  has  been  described  as  a  proper  fibrous  coat,  the  tunica  albuginea 
ovarii,  but  which  does  not  actually  exist  as  a  separate  layer. 

If  a  section  be  made  through  the  ovary,  you  will  find  that  im- 
bedded in  the  stroma  are  a  large  number  of  small  transparent 
vesicles,  which  are  more  abundant  at  the  circumference  of  the  ovary, 
while  in  the  central  part  there  are  comparatively  few,  it  being  com- 
posed almost  entirely  of  the  stroma. 

1  His,  '  Lage  der  Eierstocke,'  Archiv  f.  Aiiai.,  1881. 

2  Waldeyer,  Eierstock  u,  Ei,  Leipzig,  1870;  and  in  Strieker's  Hatidbuch,  1871. 


574  STRUCTURE   OF   THE    OVARIES. 

The  transparent  vesicles  just  alluded  to  are  the  Graafian  follicles, 
or  the  ovisacs,  which  contain  the  ova.1  In  the  outer  part  or  cortical 
layer  of  the  stroma  of  the  ovary  may  be  observed  a  large  number 
of  closely  set  minute  vesicles,  about  Yo~o^n  °f  an  inch  in  diameter, 
more  numerous  in  the  ovaries  of  young  children  and  in  some 
animals.  In  the  central  part  or  medullary  portion  of  the  stroma 
are  seen  larger  and  less  numerous  vesicles,  the  largest  being  placed 
most  deeply ;  but  these,  as  they  become  mature,  gradually  make 
their  way  towards  the  surface,  probably  by  absorption,  and  when 
fully  developed  measure  from  ^-th  to  -^th  of  an  inch  in  diameter. 
One,  or  perhaps  more  than  one,  Graafian  vesicle  ruptures  at  each 
menstrual  period,  and  the  little  ovum  it  contains  escapes  from 
the  vesicle,  and  is  either  grasped  by,  or  falls  into  the  fimbriated 
end  of  the  Fallopian  tube,  and  is  thus  conveyed  into  the  uterus. 
The  ruptured  vesicle  from  which  the  ovum  has  escaped  becomes 
filled  with  blood,  and  subsequently  also  with  an  exudation  from  its 
walls,  so  as  to  constitute  a  reddish-yellow  substance,  called  the 
corpus  luteum,  which  persists  for  a  while,  and  then  degenerates 
into  a  small  stellate  fibrous  cicatrix. 

The  Graafian  vesicles  are  very  numerous,  especially  in  the  young 
subject,  the  smaller  ones  being  the  most  numerous,  their  average 
diameter  being  about  y^-th  of  an  inch.2  External  to  the  larger 
vesicles  there  can  be  distinguished  a  membrana  propria  or  basement 
membrane;  internal  to  this,  the  stroma  becomes  altered  so  as  to 
constitute  a  distinct  wall  to  the  follicle.  Within  this,  and  lining 
the  wall  of  the  vesicle,  there  is  a  layer  of  nucleated  cells,  called  the 
membrana  granulosa,  which  surrounds  a  transparent  albuminous 
fluid  in  which  the  ovum  or  germ  is  contained.  The  vesicle,  as  it 
approaches  the  surface  of  the  ovary,  developes  an  additional  layer 
of  granular  cells,  called  the  discus  proligerus,  within  which  the  ovum 
is  imbedded,  lying  usually  towards  the  free  surface  of  the  ovary. 

The  ramifications  of  the  ovarian  artery  through  the  ovary  are 
remarkable  for  their  convolutions  ;  they  run  in  parallel  lines,  as  in 

1  So  called  after  De  Graaf,  a  Dutch  anatomist,  who  discovered  them  in  1672, 
and  believed  they  were  the  true  ova. 

2  It  has  been  computed  that  in  the  ovaries  of  a  child  at  birth  there  are  no  less 
than  70,000  Graafian  follicles. 


THE   LIVER.  575 

the  testicle.  Its  nerves  are  derived  from  the  ovarian  plexus,  which 
comes  from  the  renal.  The  ovarian  veins  form,  like  the  spermatic 
veins,  near  the  ovary,  the  pampiniform  plexus,  and  then  terminate, 
the  right  in  the  inferior  vena  cava,  the  left  in  the  renal  vein. 

The  parovarium,  or  the  organ  of  jRosenmuller,  is 
the  remains  of  a  foetal  structure  situated  in  the 
broad  ligament,  between  the  Fallopian  tube  and  the  ovary.  It 
consists  of  a  series  of  convoluted  closed  tubules,  lined  with  epi- 
thelium, converging  from  beneath  the  Fallopian  tube  to  the  ovary. 
At  their  ovarian  end  the  tubules  are  separate,  but  at  their  broader 
end  they  are  joined  by  a  longitudinal  tube  running  parallel  to  the 
lower  border  of  the  Fallopian  tube.  It  is  the  vestige  of  a  foetal 
structure,  and  is  the  analogue  of  the  epididymis  in  the  male,  and 
is  connected  at  its  uterine  end  with  the  remains  of  the  Wolffiaii 
duct. 

DISSECTION   OF   THE   ABDOMINAL   VISCEEA. 

The  liver  is  the  largest  glandular  organ  in  the 
THE  LIVER  .  . 

body,  and  in  the  adult  weighs  from  fifty  to  sixty 

ounces.  It  serves  for  the  secretion  of  the  bile,  and  moreover  alters 
some  of  the  constituents  of  the  blood  in  its  passage  through  the 
organ.  Its  diameter  in  the  transverse  direction  is  from  ten  to 
twelve  inches ;  from  before  backwards  it  measures  from  six  to 
seven  inches,  and  its  greatest  thickness,  which  is  at  its  back,  is 
about  three  inches. 

Its  surface  is  entirely  covered  with  peritoneum,  except  a  small 
part  behind,  which  is  connected  to  the  diaphragm  and  the  upper 
part  of  the  right  kidney  by  cellular  tissue,  and  again  in  the  hollow 
which  lodges  the  gall-bladder. 

The  upper  surface  is  smooth  and  convex  in  adaptation  to  the 
diaphragm,  and  is  marked  by  a  fold  of  peritoneum  running  from 
behind  forwards,  dividing  this  surface  into  two  unequal  lobes,  a 
right  and  a  left,  the  right  being  the  larger.  The  fold  of  peri- 
toneum is  the  suspensory  or  broad  ligament. 

The  under  surface  is  concave  and  irregular,  and  is  divided  into 
a  right  and  left  lobe  by  the  longitudinal  fissure.  „ 


576  THE    LIVE 

The  posterior  border  is  thick  and  round,  having  attached  to  it 
the  coronary  ligament. 

The  anterior  border  is  thin  and  sharp,  and  presents  a  notch 
indicating  the  division  into  a  right  and  left  lobe  ;  the  notch  lodges 
the  round  ligament,  which  is  the  remains  of  a  foetal  structure,  the 
umbilical  vein.  There  is  also  to  the  right  side  of  the  notch,  a  slight 
groove  corresponding  to  the  base  of  the  gall-bladder. 

The  right  border  is  thick  and  round,  the  left  is  flat  and  thin. 

The  under  surface  is  irregular,  and  is  marked 
by  five  fissures  which  map  out  the  five  lobes  (fig. 
136).  They  are,  the  longitudinal  fissure,  the  fissure  for  the  ductus 
venosus,  the  fissure  for  the  gall-bladder,  the  fissure  for  the  inferior 
vena  cava,  and  the  transverse  fissure.  The  relative  position  of  these 
fissures  (the  liver  being  in  sitii)  may  be  best  impressed  on  the 
memory  by  comparing  them  collectively  to  the  letter  H.  The 
transverse  fissure  represents  the  cross-bar  of  the  letter  ;  the  longi- 
tudinal fissure  and  the  fissure  for  the  ductus  venosus  represent  the 
left  bar ;  the  fissures  for  the  gall-bladder  and  the  vena  cava  make 
the  right  bar. 

The  longitudinal  fissure  divides  the  right  from  the  left  lobe, 
and  contains  the  round  ligament,  which  is  the  remains  of  the  um- 
bilical vein  in  the  foetus.  It  is  deeper  in  front  than  behind,  and 
is  not  infrequently  bridged  over  by  liver  tissue,  constituting  the 
pons  hepatis. 

The  fissure  for  the  ductus  venosus  is  the  continuation  backwards 
of  the  longitudinal  fissure  to  the  posterior  border  of  the  liver,  and 
contains  a  fibrous  cord,  which  is  the  obliterated  remains  of  what 
was  in  the  foetus  the  ductus  venosus. 

The  fissure  for  the  gall-bladder  is  a  shallow  depression  to  the 
right  of  the  longitudinal  fissure,  and  lodges  the  gall-bladder. 

The  fissure  for  the  inferior  vena  cava  runs  obliquely  backwards 
and  joins  at  an  acute  angle  the  fissure  for  the  ductus  venosus  at  the 
posterior  border  of  the  liver.  It  begins  close  to  the  right  extremity 
of  the  transverse  fissure,  and  is  not  uncommonly  surrounded  by 
hepatic  tissue. 

The  transverse  or  portal  fissure,  about  two  inches  in  length,  unites 
the  other  fissures,  and  transmits  the  large  vessels  which  enter  the 


LOBES   OF   THE   LIVER. 


577 


LOBES. 


liver  in  the  following  order :  in  front  is  the  hepatic  duct,  behind  is 
the  vena  portee,  and  between  them  the  hepatic  artery. 

The  lobes  of  the  liver,  five  in  number,  are  also  seen  on  its  under 
surface. 

The  riglit  lobe,  much  larger  than  the  left,  is 
separated  from  it  by  the  longitudinal  fissure  on 
its  under  aspect,  and  by  the  falciform  ligament  on  its  upper 
surface.  Its  superior  surface  is  smooth  and  convex,  somewhat 
quadrilateral  in  shape ;  on  the  under  surface  it  is  marked  by  three 
fissures — the  transverse,  and  those  for  the  gall-bladder  and  vena 

FIG.  136. 


1.  Longitudinal  fis- 

sure. 

2.  Continuation  of 

the  longitudi- 
nal fissure  (for 
the  ductus  ve- 
nosus). 

3.  Transverse     fis- 

sure. 

4.  Gall-bladder. 


5.  Vena  cava  in  its 

groove. 

6.  Right  lobe. 

7.  Left  lobe. 

8.  Lobulus  Spigelii. 

9.  Lobulus    cauda- 

tus. 

10.  Lobulus    quad- 
ratus. 


DIAGRAM    OF    THE    UNDER    SURFACE    OF    THE    LIVER. 

cava.  It  has  also  on  its  under  surface  two  shallow  fossae :  the 
anterior  (impressio  colica)  is  for  the  hepatic  flexure  of  the  colon ; 
the  posterior  (impressio  renalis)  for  the  right  kidney  and  the  supra- 
renal capsule. 

The  left  lobe  is  the  smaller;  its  upper  surface  is  smooth  and 
convex,  its  lower  is  concave  and  rests  on  the  stomach. 

The  remaining  lobes  may  be  considered  as  forming  parts  of  the 
right  lobe,  and  are  the  lobulus  Spigelii,  the  lobulus  caudatus,  and 
the  lobulus  quadratus. 

The  lobulus  Spigelii  is  a  prominent  quadrilateral  lobe,  placed 
between  the  transverse  fissure  and  the  fissures  for  the  ductus 

p  P 


578  STRUCTURE    OF   THE    LIVER. 

venosus  and  vena  cava;  behind  the  transverse  fissure  it  is  con- 
nected to  the  right  by  a  ridge,  the  lobulus  caudatus. 

The  lobulus  caudatus,  which  passes  obliquely  forwards  and 
to  the  right,  separating  the  fissure  for  the  vena  cava  from  the 
transverse  fissure. 

The  lobulus  quadratics  is  a  square  lobe  situated  between  the  gall- 
bladder, the  longitudinal  and  the  transverse  fissures.  This  lobe  is 
occasionally  connected  to  the  left  lobe  by  a  bridge  of  hepatic  sub- 
stance arching  over  the  longitudinal  fissure,  and  alluded  to  before 
as  the  pons  hepatis. 

The  liver  has  five  ligaments,  of  which  the 
coronary,  the  right  and  left  lateral,  and  the  falci- 
form are  reflections  of  the  peritoneum ;  the  fifth  is  the  round  liga- 
ment, placed  in  the  anterior  free  border  of  the  falciform  ligament  in 
the  longitudinal  fissure  ;  it  consists  of  the  remains  of  the  umbilical 
vein  of  the  foetus.  The  ligaments  have  been  already  described 
(p.  455). 

The  vessels  which  pass  to  and  from  the  liver  are 

five  also  in  number  :  the  hepatic  artery,  the  vena 

portae,  the  hepatic  veins,  the  hepatic   duct,  and  the  lymphatics. 

The  consideration  of  these  is  deferred  till  we  have  examined  the 

capsule  of  the  liver. 

The  fibrous  coat  surrounds  the  liver,  and  is  best  seen  on  those 
parts  of  it  not  covered  with  peritoneum.  This  coat  is  connected 
on  the  surface  of  the  gland  to  the  areolar  tissue  which  surrounds 
the  lobules,  but  does  not  send  down  partitions  to  form  a  framework 
for  the  interior.  It  is  continuous,  at  the  transverse  fissure,  with 
the  sheath  of  loose  areolar  tissue,  called  Glissoris  capsule,  which 
surrounds  the  vessels  as  they  enter  that  fissure,  and  encloses  them 
in  a  common  sheath  in  their  ramifications  through  the  liver. 

The  interlobular  connective  tissue  is  exceedingly  delicate :  hence 
the  great  liability  of  the  liver  to  be  lacerated  by  external  violence, 
and  consequent  haemorrhage  into  the  peritoneal  cavity. 

The  liver  consists  of  an  aggregation  of  small 
LOBULES.  ,  °° 

polyhedral  masses,  called  lobules,  about  the  size  or 

a  millet  seed,  which  range  from  ^th  to  ^th  of  an  inch  (1  to  2 
millimetres)  in  diameter.     These  lobules  are  more  or  less  distinctly 


STRUCTURE    OF    THE    LIVER. 


579 


marked  out  by  septa  of  areolar  tissue,  and  in  a  transverse  section 
have  the  appearance  of  mosaic  pavement  (fig.  137) ;  but  in  a  per- 
pendicular section  they  somewhat  resemble  an  oak  leaf  (fig.  138). 
Each  lobule  is  mapped  out  by,  and  separated  from,  the  adjacent 
lobules  by  delicate  connective  tissue,  in  which  runs  a  plexus  of 
vessels — interlolndar  plexus — consisting  of  branches  of  the  portal 
From  this  plexus  passes  inwards  into  the  lobule  a  fine 


vein. 


capillary  network,  whose  branches  converge  to  the  centre  of  the 
lobule  and  end  in  a  single  vein,  the  intralobular  vein,  which,  in  its 


FIG.  137. 


«.  Interlobular  vein. 


6.  Intralobular     or     cen- 
tral vein. 


TRANSVERSE  SECTIONS  OF  THREE  LOBULES  OF  THE  LIVER,  MAGNIFIED  TO  SHOW 
THE  PORTAL  VENOUS  PLEXUS. 

(After  Kiernan.) 

turn,  opens  into  the  sublolular  vein,  and  thence  into  the  hepatic 
•vein.  With  the  interlobular  plexus  run  the  biliary  ducts.  The 
lobules  themselves  consist  of  a  minute  plexus  of  blood-vessels, 
ducts,  and  cells — liepatic  cells — which  latter  fill  up  the  spaces 
between  the  ramifications  of  the  vessels.  It  will  facilitate  the  un- 
derstanding of  the  different  hepatic  vessels,  if  it  be  borne  in  mind, 
(1)  that  the  portal  vein,  hepatic  artery,  and  hepatic  duct  ramify 
together  from  first  to  last,  enclosed  in  a  common  sheath  of  con- 
nective tissue,  called  Glisson's  capsule  ;  (2)  that  the  hepatic  veins 
run  alone  from  first  to  last,  and  terminate  in  the  inferior  vena  cava 
as  it  passes  under  the  liver. 

p  p  2 


580  STRUCTURE    OF   THE    LIVER. 

The  portal  vein  enters  the  transverse  fissure  of  the  liver,  ac- 
companied by  the  entering  hepatic  artery  and  the  emerging  right 
and  left  hepatic  ducts,  which  as  before  stated  are  surrounded  in 
the  liver  by  a  common  sheath  called  Glisson's  capsule.  In  the 
liver,  the  portal  vein  ramifies  between  the  lobules  and  gives  off 
numerous  branches,  called  interlobular  or  peripheral  veins,  which 
pass  between  the  lobules  and  communicate  freely  with  each  other. 
These  receive  the  vaginal  and  capsular  veins  which  convey  the 
blood  from  the  corresponding  branches  of  the  hepatic  artery.  The 
interlobular  plexus  of  veins  gives  off  a  minute  capillary  network, 
which  penetrates  into  the  interior  of  the  lobule,  and  converges  to- 
wards the  centre  of  the  lobule  to'  open  directly  into  a  single  central 
vein  called  the  intralobular  vein.  The  capillaries  which  compose 
this  network  run  in  a  nearly  parallel  direction  from  the  circumference 
to  the  centre  of  the  lobule,  and  communicate  freely  with  each  other 
by  small  transverse  branches.  The  intervals  between  the  branches  of 
the  capillary  network  is  very  small,  varying  from  y^-g-th  to  -^-^th 
of  an  inch,  while  the  vessels  themselves  are  comparatively  large, 
F  ^  .  being  about  ^o^th  of  an  inch  in 

diameter.  The  intralobular  vein  re- 
turns the  blood  from  the  centre  of 
the  lobule,  and  opens  immediately 
into  a  sublobular  vein,  larger  or 
smaller  as  the  case  may  be,  upon 
which  the  lobule  is  sessile  (fig.  138). 
The  sublobular  veins,  increasing 
in  size,  empty  themselves  into  the 

LONGITUDINAL       SECTIONS        OF        THE  n  7  ,  •  •  ,  i  •. 

smaller  fiepaUc  veins  ;  these  unite  to- 


LOBULES  OF  THE  LIVER. 

LOBULAB  VEINS  SEEN  JOINING  THE    form  the  main  hepatic  trunks,  usually 

SUBLOBULAK.  ,  ,  ,  ,  , 

three  in  number,  one  each  from  the- 

right  and  left  lobes  and  the  lobulus  Spigelii.  These  hepatic  veins 
open  into  the  inferior  vena  cava,  as  this  vessel  passes  to  the  posterior 
border  of  the  liver. 

The  hepatic  artery,  entering  the  transverse  fissure  of  the  liver, 
divides  and  subdivides  with  the  portal  vein  and  biliary  ducts,  and 
ramifies  with  them  between  the  lobules.  The  artery  distributes 
branches  —  vaginal  branches  —  whilst  within  the  portal  canals  which 


STRUCTURE   OF   THE   LIVER.  581 

supply  the  coats  of  the  hepatic  vessels  and  Glisson's  capsule ;  also 
•capsidar  branches  to  the  fibrous  coat  of  the  liver  which  appear 
on  the  surface  of  the  liver  in  stellate  plexuses ;  and  interlobular 
branches  which  accompany  the  corresponding  veins  and  pass  into  the 
lobules  to  join  the  capillary  network  which  leads  to  the  radicles 
of  the  intralobular  vein. 

The  interior  of  each  lobule — that  is,  the  space  left  between  the 
several  vessels — is  filled  by  the  hepatic  cells.  They  are  of  spheroidal 
or  polyhedral  shape,  with  a  diameter  varying  from  ^y^-th  to  -3-5 -0th 
of  an  inch,  and  have  no  cell-wall.  They  consist  of  a  granular  sub- 
stance of  a  light  yellow  tinge,  containing  one  or  more  distinct 
nuclei  having  a  highly  refracting  nucleolus.  In  some  cases  the 
cells  contain  fat  globules ;  when  these  accumulate  in  large  quanti- 
ties, they  constitute  what  is  called  a  fatty  liver.  The  office  of  the 
hepatic  cells  is  to  separate  the  bile  from  the  blood,  and,  when  filled 
with  bile,  to  discharge  their  contents  into  the  biliary  ducts. 

The  biliary  ducts  are  the  channels  through  which  the  bile 
is  conveyed  into  the  hepatic  ducts.  They  commence  as  minute 
passages — bile  canaliculi — which  are. formed  between  and  around 
the  hepatic  cells,  and  then  pass  outwards  to  the  circumference  of 
the  lobule,  where  they  open  into  the  bile-ducts  between  the  lobules.1 
Here  they  form  a  plexus — interlobular — which  opens  into  ducts 
which  run  with  the  hepatic  artery  and  portal  vein  in  the  portal 
canals ;  eventually  these  join  with  other  ducts  to  form  the  right 
and  left  hepatic  ducts,  which  leave  the  transverse  fissure  of  the  liver, 
and,  after  a  course  of  about  an  inch,  unite  to  form  a  single  duct, 
the  common  hepatic  duct. 

The  lymphatics  of  the  liver  are  arranged  in  two  sets :  super- 
ficial and  deep.  The  superficial  may  be  divided  into  those  on  the 
upper  convex  surface,  and  those  on  the  under  aspect ;  the  lymph- 
atics on  the  convex  surface  are : — (1)  those  which  run  back- 
wards between  the  layers  of  the  falciform  ligament,  and  then  pass 
through  the  diaphragm  behind  the  ensiforin  cartilage  to  enter  the 

1  The  biliary  ducts  between  the  lobules  are  lined  with  a  short  columnar  epi- 
thelium, resting  on  a  basement  membrane  ;  but  it  is  doubtful  whether  the  bile- 
canaliculi  are  very  minute  ducts,  or  whether  they  are  not  simple  intercellular 
passages  between  the  hepatic  cells. 


582  FUNCTIONS   OF   THE   LIVER. 

anterior  mediastinal  glands,  and  thence  to  the  right  lymphatic 
duct ;  (2)  those  which  pass  forwards  over  its  anterior  margin  to 
the  under  aspect,  to  enter  the  glands  in  the  gastro-hepatic  omen- 
turn  ;  (3)  those  which  run  to  the  right  lateral  ligament,  and  then 
either  pierce  the  diaphragm  to  join  the  anterior  mediastinal  glands, 
or  pass  inwards  to  open  into  the  thoracic  duct  at  its  commence- 
ment ;  and  (4)  those  which  run  to  the  left  lateral  ligament,  which, 
after  piercing  the  diaphragm,  open  into  the  anterior  mediastinal 
glands.  The  lymphatics  on  the  under  aspect  are  arranged  as 
follows : — (1)  those  on  the  right  side  of  the  gall-bladder  open  into 
the  lumbar  glands ;  (2)  those  surrounding  the  gall-bladder  accom- 
pany the  hepatic  artery  to  join  the  glands  in  the  gastro-hepatic 
omentum ;  (3)  those  on  the  left  side  enter  the  glands  on  the  lesser 
curve  of  the  stomach  and  the  oesophagus.  The  deep  lymphatics 
originate  partly  in  the  connective  tissue  between  the  lobules,  and 
there  accompany  the  hepatic  artery  and  portal  vein  and  duct  to 
the  transverse  fissure,  to  join  the  lymphatic  glands  on  the  lesser 
curve  of  the  stomach  and  behind  the  pancreas ;  some  lymphatics 
also  accompany  the  branches  of  the  hepatic  veins. 

The  nerves  of  the  liver  are  derived  from  the  pneumogastric, 
chiefly  the  left,  and  from  the  hepatic  plexus  which  comes  from  the 
coeliac  plexus.  These  plexuses  enter  the  liver  at  the  transverse 
fissure,  surround  the  hepatic  artery  and  the  portal  vein,  and 
accompany  these  vessels  in  their  ramifications  through  it.  The 
ultimate  termination  of  these  nerves  is  not  known. 

The  functions  of  the  liver  may  be  thus  briefly  expressed : — 
1.  It  renders  the  albuminous  matter  (albuminose),  brought  to  it 
by  the  portal  vein,  capable  of  being  assimilated.  2.  It  forms  a 
substance,  glycoyen,  easily  converted  into  sugar,  which  passes  into 
the  hepatic  veins,  and,  being  consumed,  helps  to  maintain  animal 
heat.  3.  It  secretes  the  bile,  which  assists  in  converting  the 
chyme  into  chyle,  and  reducing  it  into  a  state  fit  to  be  absorbed 
by  the  lacteals.  4.  The  bile  acts  as  a  natural  aperient.  5.  The 
bile  is  an  antiseptic,  and  probably  prevents  the  decomposition  of 
the  food  during  its  passage  through  the  intestine. 

The   gall-bladder,  or  reservoir  for  the  bile,  is 

GALL-BLADDER.  .„  .         ,  ,.  „       ,    .  1-1, 

pyritorm   in    shape,  and  is  confined  in  a  slight 


STRUCTURE   OF  THE   GALL-BLADDER.  583 

depression  on  the  under  surface  of  the  right  lobe  of  the  liver 
(p.  455).  It  is  about  four  inches  long,  an  inch  in  its  broadest 
part,  and  is  capable  of  holding  about  1^  oz.  of  fluid.  Its  broadest 
part  projects  beyond  the  anterior  margin  of  the  liver,  and  it  is 
maintained  in  its  position  by  the  peritoneum,  which  usually  is  con- 
tinued over  it  from  the  liver,  but  which  may  occasionally  com- 
pletely invest  it,  so  as  to  form  a  kind  of  mesentery.  It  is  divided 
into  a  fundus,  a  body,  and  a  neck.  The  fundus  is  its  broadest 
part,  and  usually  projects  a  little  beyond  the  front  border  of  the 
liver ;  from  this  it  gradually  narrows,  forming  the  body  ;  and  this 
again  still  further  contracts  to  form  the  neck,  which  makes  a  bend 
downwards,  curving  upon  itself  like  the  letter  S.  The  neck  ter- 
minates in  a  duct  called  the  cystic  duct,  which,  after  a  course  of 
about  an  inch,  joins  the  common  hepatic  duct  at  an  acute  angle 
(fig.  109,  p.  467).  The  common  duct  thus  formed,  called  the  ductus 
communis  choledochus,  is  about  three  inches  long,  and  of  the  size 
of  a  crow-quill ;  it  opens  into  the  inner  side  of  the  back  of  the 
descending  part  of  the  duodenum,  after  running  very  obliquely 
through  the  coats  of  the  bowel. 

The  gall-bladder  consists  of  two  coats,  and  of  a  partial  peri- 
toneal covering  which  only  completely  surrounds  the  fundus. 

The  middle  coat  consists  of  strong  connective  tissue,  whose  fibres 
interlace  in  all  directions,  and  in  which  involuntary  muscular  fibres 
can  be  traced,  running  mainly  in  the  long  axis  of  the  gall-bladder. 

The  mucous  coat  can  only  be  seen  when  the  gall-bladder  has 
been  opened,  which  should  now  be  done,  by  laying  it  open  from 
the  fundus  to  the  neck.  It  is  loosely  connected  to  the  middle 
coat,  and  it  is  gathered  into  ridges,  which  give  it  a  honeycombed 
appearance,  more  or  less  tinged  yellowish-brown  by  the  bile.  This 
appearance  is  most  marked  in  the  middle  of  the  gall-bladder, 
where  the  surface  is  covered  with  polygonal  ridges  enclosing  de- 
pressions, in  which  may  be  seen  with  a  lens  numerous  openings 
leading  down  to  mucous  follicles.  It  is  covered  with  columnar 
epithelium,  which  secretes  an  abundance  of  viscid  mucus.  At  the 
bend  of  the  neck  of  the  gall-bladder,  both  its  coats  project  very 
much  into  the  interior,  making  the  opening  considerably  narrower 
than  it  appears  to  be  outside.  In  the  cystic  duct  the  mucous 


584  STRUCTURE  OF  THE  PANCREAS. 

membrane  presents  a  series  of  folds,  so  arranged  one  after  the 
other  as  to  form  a  complete  spiral  valve.  The  probable  use  of  this 
is  to  prevent  the  too  rapid  flow  of  the  bile.  The  gall-bladder 
appears  to  serve  mainly  as  a  reservoir  for  the  bile  while  digestion 
is  not  going  on.  The  bile  becomes  during  its  sojourn  in  the  gall- 
bladder very  viscid  and  intensely  bitter. 

The  gall-bladder  is  supplied  with  blood  from  the  cystic  branch  of 
the  right  hepatic  artery ;  its  blood  is  returned  by  the  cystic  vein, 
which  opens  into  the  vena  portse ;  its  nerves  are  derived  from  the 
cceliac  plexus,  which  accompany  the  hepatic  artery. 

The  pancreas  is  a  large  gland  belonging  to  the 
PANCKEAS.  .          *T   . 

acmo-tubular    class.       It    is   placed   transversely 

across  the  posterior  wall  of  the  abdomen,  and  measures  from  six  to 
eight  inches  in  length,  about  an  inch  and  a  half  in  breadth,  and 
from  half  an  inch  to  an  inch  in  thickness  ;  its  weight  being  usually 
from  two  to  three  and  a  half  ounces. 

It  presents  for  examination  a  head,  a  body,  and  a  tail. 

The  head,  situated  to  the  right  side,  is  turned  down,  and  is 
embraced  by  the  descending  and  transverse  portions  of  the  duo- 
denum, the  superior  and  inferior  pancreatico-duodenal  arteries  run- 
ning between  them.  A  considerable  prolongation  usually  extends 
upwards  from  the  posterior  part  of  the  gland,  and  reaches  the  lesser 
curve  of  the  stomach :  this  constitutes  sometimes  a  separate  mass, 
and  is  then  termed  the  lesser  pancreas. 

The  tail  is  the  narrow  end  of  the  pancreas,  which  extends  to 
the  left  as  far  as  the  hilum  of  the  spleen. 

The  body  is  convex  in  front,  and  is  covered  by  the  ascending 
layer  of  the  transverse  meso-colon. 

The  pancreas  has  a  posterior  surface  which  is  concave,  and  lies 
on  the  vena  cava,  the  aorta,  the  crura  of  the  diaphragm,  the  superior 
mesenteric  artery  and  vein,  the  commencement  of  the  vena  portae, 
and  the  inferior  mesenteric  vein ;  an  upper  border  which  is  thick, 
and  is  in  relation  with  the  splenic  artery  and  vein,  the  cceliac  axis, 
the  hepatic  artery,  and  the  first  portion  of  the  duodenum ;  and  a  lower 
border  which  is  thin,  and  is  in  relation  with  the  superior  mesenteric 
artery  and  vein,  and  on  its  left  with  the  inferior  mesenteric  vein. 

The  duct  of  the  pancreas,  called  also  the  duct  of  Wirsung,  passes 


STRUCTURE  OF  THE  PANCREAS.  585 

from  left  to  right  in  the  pancreas,  nearer  its  lower  than  its  upper 
border,  and  nearer  its  anterior  than  its  posterior  surface.  Com- 
mencing at  the  tail  by  the  junction  of  the  smaller  ducts,  it  receives, 
in  its  course  to  the  right  side,  repeatedly,  other  ducts,  and  thus 
gradually  increases  in  size  until  it  reaches  the  head,  where  it  usually 
receives  a  large  branch  from  the  lesser  pancreas ;  the  large  duct 
then  curves  downwards,  and  comes  into  relation  with  the  common 
bile  duct ;  it  then  passes  very  obliquely  through  the  coats  of  the  de- 
scending duodenum  on  its  posterior  aspect,  and  then  either  opens 
separately,  or  in  conjunction  with  the  common  bile  duct,  into  this 
portion  of  the  intestine. 

The  structure  of  the  pancreas  resembles  in  most  of  its  characters 
that  of  the  salivary  glands.  The  alveoli  are  tubular,  frequently 
convoluted,  and  are  lined  by  columnar  epithelium,  which  leaves  only 
a  narrow  lumen,  which  is  often  occupied  by  spindle-shaped  cells 
called  the  centro-acinar  cells. l  The  ducts  are  very  constricted  at 
their  commencement  from  the  alveolus,  and  are  lined  •  by  short 
columnar  epithelial  cells,  which  become  larger  towards  the  termi- 
nation of  the  duct. 

The  arteries  of  the  pancreas  are  derived  from  the  splenic,  the 
superior  and  inferior  pancreatico-duodenal  branches,  respectively,  of 
the  hepatic  and  the  superior  mesenteric  arteries.  The  veins  open 
into  the  splenic  and  superior  mesenteric  veins.  The  lymphatics  end 
in  the  lumbar  glands ;  its  nerves  are  derived  from  the  solar  plexus. 

The  uses  of  the  pancreatic  fluid  are :  to  convert  the  starchy 
matters  into  dextrine  and  grape  sugar  ;  to  emulsify  (in  conjunction 
with  the  bile)  the  fatty  particles,  and,  by  its  alkaline  salts,  partly 
saponify  the  fatty  acids,  thus  enabling  them  to  be  taken  up  by  the 
lacteals ;  and,  lastly,  to  convert  into  peptones  the  albuminous  and 
gelatinous  substances  of  food.  It  is  an  alkaline  fluid,  very  similar 
to  that  secreted  in  the  salivary,  glands,  but  contains  no  sulpho- 
cyanogen. 

The  spleen  is  a  very  vascular  sponge-like  organ, 

and  belongs  to  the  class  of  ductless  glands.2     It 

varies  in  size  according  to  the  amount  of  blood  in  it,  fluctuating  in 

1  Langerhans,  Beitrage,  &c.,  Berlin,  1869. 

2  The  other  ductless  glands  are,  the  thyroid,  thymus,  and  supra-renal  capsules. 


586  STRUCTURE  OF  THE  SPLEEN. 

weight,  consistently  with  health,  between  five  and  ten  ounces.1  It 
is  of  a  reddish-blue  colour,  is  more  or  less  elliptical  in  shape,  and, 
in  its  natural  position,  is  placed  with  its  long  axis  nearly  vertical. 
It  is  about  five  inches  in  length,  three  to  four  inches  in  breadth, 
and  from  one  to  one  and  a  half  inch  in  thickness.  Its  outer  surface 
is  smooth  and  convex,  and  corresponds  to  the  ninth,  tenth,  and 
eleventh  ribs  on  the  left  side,  being  in  relation  with  the  under 
aspect  of  the  diaphragm  ;  its  inner  surface  is  concave,  and  is  adapted 
to  the  cardiac  end  of  the  stomach  ;  this  surface  is  divided  into  a 
larger  anterior  and  a  smaller  posterior  portion  by  a  vertical  fissure 
— the  lulwn — at  the  bottom  of  which  are  large  openings,  through 
which  the  vessels  enter  and  emerge  from  the  spleen.  The  borders 
are :  an  upper,  thick  and  rounded ;  a  loiver,  pointed  ;  a  posterior, 
rounded  ;  and  an  anterior,  also  rounded,  and  often  notched. 

As  already  mentioned,  the  spleen  is  connected  to  the  stomach 
by  the  y  astro-splenic  omentum,  and  to  the  under  aspect  of  the  dia- 
phragm by  the  suspensory  ligament. 

The  spleen  is  invested  with  two  coats — a  serous  or  peritoneal, 
and  a  fibro-elastic.  The  outer  or  serous  coat  entirely  covers  the 
organ,  except  at  the  hilum,  from  which  it  is  reflected  to  the  stomach ; 
it  is  thin  and  smooth,  and  is  intimately  connected  to  the  subjacent 
fibrous  coat.  Itsfilro-elastic  coat  (tunica  propria),  thick  and  strong, 
not  only  covers  the  spleen,  but  sends  inwards  throughout  its  sub- 
stance fibrous  bands  (trabeculce),  which  interlace  in  all  directions, 
and  thus  form  an  intricate  network  of  what  are  termed  trabecular 
spaces  or  areolce  ;  this  coat  consists  of  a  strong,  white,  and  elastic 
tissue,  and  is  consequently  exceedingly  elastic  to  admit  of  the  vary- 
ing size  of  the  spleen  ;  it  moreover  contains  more  or  less  unstriped 
muscular  fibres,  so  that  it  contracts  faintly  on  the  application  of 
the  galvanic  current.  Besides  this,  the  trabeculse  form  sheaths  and 
supports  for  the  splenic  vessels  throughout  their  ramifications. 

The  areolae,  above  described,  are  filled  with  what  is  termed 
the  spleen  pulp.  This  pulp  is  a  soft  reddish-brown  substance, 
and,  under  the  microscope,  is  seen  to  consist  of  connective-tissue 

1  In  ague  and  other  forms  of  fever,  it  sometimes  attains  a  weight  of  from  18 
to  20  pounds  ;  it  diminishes  in  weight  after  forty  years  of  age,  and  is  enlarged  during 
and  after  digestion. 


STRUCTURE  OF  THE  SPLEEN.  587 

corpuscles,  which,  with  their  branched  communicating  processes, 
called  the  sustentacular  cells  of  the  pulp,  make  up  a  fine  reticular 
tissue ;  the  interstices  of  which  are  filled  with  red  and  white  blood- 
corpuscles.  Thus  the  areolae  are  divided  into  a  large  number  of 
smaller  spaces  by  these  sustentacular  cells,  and  the  white  blood- 
cells  contained  within  them  are  more  numerous  than  in  normal 
blood,  especially  in  the  neighbourhood  of  the  Malpighian  corpuscles. 
The  cells  have  either  one  or  more  nuclei  according  to  their  size,  and 
present  distinct  amoeboid  movements.  In  these  cells  frequently 
small  yellowish  granules  may  be  distinguished,  which  are  probably 
derived  from  blood-cells,  for  they  present  all  the  characters  of 
hsematin.  Blood-corpuscles  in  all  stages,  from  an  unchanged  disc 
to  one  of  complete  disintegration,  may  be  seen  ;  and  it  has  been 
shown  by  Klein  that  some  of  them  present  knob-like  projections, 
as  if  from  budding  of  small  nuclei  by  a  process  of  gemmation. 

The  splenic  artery  enters  the  hilum  of  the  spleen  by  several 
branches  which  ramify  in  its  substance,  ensheathed  and  supported 
by  its  fibrous  framework.1  The  artery  is  remarkable  for  its  large 
size,  as  compared  with  the  organ  to  which  it  is  distributed,  and 
also  for  its  serpentine  course.  The  smaller  branches  leave  the 
trabeculge,  still  invested  by  a  sheath  derived  from  the  fibro-elastic 
coat  of  the  spleen ;  but,  before  they  terminate  in  penicillate  tufts, 
the  sheath  becomes  changed  into  a  thick  investment  of  lymphoid 
tissue,  which  surrounds  the  smallest  arterioles.  The  lymphoid 
tissue,  which  forms  the  sheath  of  the  arterioles,  is  here  and  there 
dilated  into  oval  enlargements,  called  the  Malpighian  corpuscles, 
varying  in  size  from  -^th  to  ^§-th  of  an  inch  in  diameter.  These 
bodies  are  sometimes  thickenings  on  the  side  of  the  arterioles,  but 
more  commonly  they  completely  surround  the  vessels.  They  are 
visible  in  a  fresh  spleen,  and  look  like  white  spots  scattered  through 
the  dark  pulp.  There  do  not  appear  to  be  any  definite  boundaries 
between  them  and  the  reticular  tissue  ;  their  interior  consists  of  a 
fine  reticulum,  denser  at  the  circumference  than  at  the  centre,  and 
is  filled  with  lymphoid  cells  possessing  amoeboid  movements.  The 
smaller  arteries,  after  branching  in  all  directions,  enter  the  spleen 

1  The  ramifications  of  the  splenic  artery  may  be  seen  by  washing  away  the 
pulp,  and  floating  the  flocculent -looking  spleen  in  water. 


588  STRUCTURE  OF  THE  SPLEEN. 

pulp,  and  their  lymphoid  walls  alter  in  character,  presenting 
numerous  branched  processes  which  communicate  with  the  branched 
cells  of  the  sustentacular  tissue.  Through  this  connection  they 
pour  their  blood  directly  into  the  pulp  tissue,  and  thus  into  relation 
with  the  constituents  of  the  pulp  tissue,  by  which  means  it  is  sub- 
jected to  important  changes.  The  veins  commence  in  the  pulp 
tissue  in  the  same  way  as  the  arteries,  and  are  at  first  formed 
by  the  arrangement  into  rows  of  the  connective-tissue  corpuscles, 
which  subsequently  become  spindle-shaped  and  overlap  each  other, 
so  constituting  a  variety  of  endothelial  lining  to  the  venous  passages. 
Assuming  more  the  ordinary  character  of  veins,  they  travel  along 
the  trabeculge  like  the  arteries,  but  do  not  accompany  them,  and 
freely  communicate  with  each  other,  and  so  far  are  unlike  the 
arteries.  The  small  veins  present  transverse  lines  or  markings, 
caused  by  the  encircling  elastic  fibres  around  the  vessels  of  the  sus- 
tentacular tissue  of  the  spleen.  After  entering  the  trabecular  tissue 
which  forms  sheaths  for  the  veins,  they  gradually  join  and  form  four 
to  six  large  veins,  which  leave  the  hilum  to  constitute  the  splenic 
vein. 

The  lymphatics  of  the  spleen  are  arranged  in  two  sets — a  trabe- 
cular and  a  perivascular :  the  former  originate  in  the  trabeculae,  and 
are  connected  with  the  lymphatics  beneath  the  capsule ;  the  latter 
arise  in  the  lymphoid  tissue  around  the  arteries,  and  subsequently 
run  one  on  each  side  of  the  arteries,  anastomosing  frequently  by 
transverse  branches.  The  trabecular  and  peri  vascular  lymphatics 
join  at  the  hilum,  and  run  between  the  layers  of  the  gastro-splenic 
omentum  to  the  lymphatic  glands. 

The  nerves  come  from  the  solar  plexus  and  the  right  pneumo- 
gastric  nerve. 

The  function  of  the  spleen  appears  to  be  that  of  a  great  blood- 
gland,  and  thus  concerned  in  the  development  of  white  corpuscles ; 
for  the  blood  which  is  conveyed  from  the  spleen  contains  a  large 
excess  of  white  corpuscles.  The  large  number  of  red  blood-cor- 
puscles, in  various  stages  of  disintegration,  also  points  to  another 
use  of  the  spleen  as  the  gland  for  the  degeneration  of  red  blood- 
cells  into  pigment,  which  is  conveyed  through  the  spleen  to  the 
liver  to  be  used  in  the  secretion  of  the  bile.  It  is  also  presumed 


STRUCTURE  OF  THE  KIDNEY.  589 

that  the  gland  elaborates  the  albuminous  materials  of  food,  and  stores 
them  up  for  a  time  before  they  pass  into  the  circulation. 

The  kidneys,  two  in  number,  are  situated  in  the 
lumbar  region,  behind  the  peritoneum,  imbedded 
in  fat.  The  left,  usually  situated  higher  than  the  right,  is  gener- 
ally longer  and  somewhat  heavier.  Their  colour  is  reddish-brown. 
Each  is  about  four  inches  in  length,  two  inches  and  a  half  in  breadth, 
and  one  inch  and  a  quarter  in  thickness.  Each  weighs  about  4|- 
ounces  in  the  male,  and  rather  less  in  the  female. 

The  kidney  presents  for  examination  two  surfaces,  two  borders, 
and  an  upper  and  a  lower  end. 

The  anterior  surface  is  convex  and  is  covered  with  peritoneum, 
and  looks  somewhat  outwards ;  the  posterior  surface  is  rather  flat- 
tened, and  rests  on  the  anterior  layer  of  the  lumbar  aponeurosis 
and  psoas  magnus ;  the  outer  border  is  convex  and  rounded ;  the 
inner  border  presents,  about  its  middle,  a  deep  notch  about  an  inch 
in  length,  the  hilum,  leading  to  a  hollow  in  the  kidney,  the  sinus, 
for  the  entrance  and  exit  of  the  renal  vessels  and  ureter,  the  nerves 
and  lymphatics ;  these  have  the  following  relations  to  one  another : 
in  front  lies  the  renal  vein ;  behind  is  the  ureter ;  between  them 
is  the  renal  artery ;  the  upper  end  is  large  and  thick,  and  looks 
upwards  and  inwards,  and  upon  it  rests  its  corresponding  supra- 
renal capsule ;  the  lower  end.  smaller  and  flatter  than  the  upper 
end,  looks  downwards  and  outwards. 

The  kidney  is  surrounded  by  a  thin  fibrous  capsule  of  thick 
connective  tissue,  to  which  it  is  loosely  connected  by  areolar  tissue 
and  minute  vessels,  except  at  the  hilum ;  here  it  is  reflected  inwards 
and  becomes  continuous  with  the  walls  of  the  renal  vessels  and 
ureter.  The  capsule  can  be  readily  stripped  oft0  when  healthy, 
leaving  the  surface  perfectly  smooth.1 

A  longitudinal  section  should  be  made  through  the  kidney, 
from  the  outer  to  the  inner  border,  to  demonstrate  the  interior. 
This  section  displays  two  distinct  parts — an  outer  or  cortical  portion, 
and  an  inner  or  medullary  portion. 

The  cortical  structure  is  deeper  in  colour  than  the  medullary 

1  Under  the  capsule  there  have  been  traced  unstriped  muscular  fibres  forming 
an  incomplete  layer. 


590 


STRUCTURE    OF    THE    KIDNEY. 


FIG.  139. 


portion,  and  is  soft  and  easily  lacerated.     It  forms  the  external 
portion  of  the  kidney  to  the  extent  of  four  to  five  lines,  arching 

over  the  bases  of  the  pyramids. 
It  moreover  sends  down  prolonga- 
tions between  the  pyramids  as  far 
as  the  sinus,  forming  the  septula 
renum  or  the  columns  of  Bertini. 
The  cortical  substance  consists 
of  convoluted  and  straight  tubes, 
tubuli  uriniferi,  of  little  reddish 
granules  called  Malpinliian  bodies, 
and  of  blood-vessels,  nerves,  and 
lymphatics  (fig.  139). 

The  medullary  structure  is 
composed  of  numerous  conical 
masses,  the  pyramids  of  Malpiglii, 
having  their  bases  directed  to  the 
surface,  their  sides  in  relation 
with  the  columns  of  Bertini,  and 
their  apices,  termed  papillm  or 
mammillce,  projecting  into  one  of 
the  calices  of  the  ureter.  The 
pyramids,  of  which  there  are  from 
eight  to  sixteen,  are  surrounded 
by  the  cortical  substance  ;  they 
are  composed  of  minute  straight  tubules  (which  proceed  from  the 
cortical  portion  to  end  in  the  papillee),  of  looped  tubes  described  by 
Henle,  and  of  arteries  and  veins.1 

At  the  hilum  is  the  dilated  commencement  of  the  ureter,  called 
the  pelvis  of  the  kidney.  It  is  funnel-shaped,  and  its  broad  part 
divides  into  thre.e  principal  channels,  infundibula,  an  upper,  middle, 
and  lower,  which  again  branch,  and  form  from  eight  to  twelve  cup- 

1  Each  pyramid  represents  what  was,  in  the  early  stage  of  the  kidney's  growth, 
a  distinct  and  independent  lobe.  In  the  human  subject  the  lobes  gradually  coalesce, 
and  no  trace  of  their  primordial  state  remains,  except  the  pyramidal  arrangement 
of  the  tubes.  But  in  the  kidneys  of  the  lower  mammalia,  of  birds  and  reptiles, 
the  lobes  are  permanently  separate. 


SECTION    OF    THE    KIDNEY. 

1.  Ureter. 

2.  Pelvis  of  the  kidney. 

3.  3,  3.  Papilte. 


STRUCTURE   OF   THE   KIDNEY.  591 

like  excavations,  called  calicos.  Into  each  of  these  calices  one, 
sometimes  two  or  more  papillae  project.  Between  the  calices  the 
branches  of  the  renal  artery  ascend  to  ramify  in  the  kidney,  lying 
imbedded  in  fat.  The  pelvis  and  the  calices  are  composed  of  three 
layers — an  external  fibrous  layer  continuous  with  the  reflected  part 
of  the  capsule  into  the  sinus ;  a  middle  or  muscular,  consisting  of 
longitudinal  and  circular  fibres,  the  former  extending  nearly  as  far 
as  the  calices,  the  latter  encircling  the  calyx  round  the  papillas; 
and  an  interned  or  mucous  coat  reflected  over  the  papillae. 

STRUCTURE  OF  With  a  lens,  each  papilla  may  be  seen  to  be 
THE  KIDNEY.  studded  with  minute  apertures,  which  are  the  termi- 
nations of  the  tubuli  uriniferi.  These  apertures  open  into  the  bottom 
of  about  twenty  shallow  depressions  on  a  papilla,  called  foveola;. 
The  orifices  are  from  -j-Jpo  th  to  ^-^th  of  an  inch  in  diameter.  These 
tubes  as  they  pass  out  into  the  pyramidal  structure  run  straight, 
bifurcate  repeatedly  at  very  acute  angles,  their  subdivisions  running 
parallel,  and  reach  the  bases  and  sides  of  the  pyramids,  from  which 
they  pass  into  the  cortical  substanca,  greatly  increased  in  number. 
These,  termed  the  straight  or  collecting  tubes,  pass  into  the  cor- 
tical substance  still  as  straight  tubes,  the  central  ones  passing 
nearly  to  the  surface,  the  outer  ones  being  very  short,  and  only 
run  a  short  distance  into  the  cortex,  so  that  they  are  arranged 
as  a  series  of  cones,  with  their  apices  to  the  surface  of  the  organ. 
These  bundles  are  called  the  pyramids  of  Ferrein,  or  the  medullary 
rays,  and  receive  on  each  side  the  curved  extremities  of  the  con- 
voluted tubes.  We  find  the  cortical  substance  is  arranged  between 
and  around  these  medullary  rays,  which,  from  the  intricate  arrange- 
ment of  its  tubes,  receives  the  name  of  the  labyrinth  of  the  cortex. 

Each  .uriniferous  tubule  commences  in  a  dilated  extremity, 
termed  the  Malpighian  capsule,  in  which  is  enclosed  an  arterial 
vascular  tuft,  the  Malpighian  tuft,  of  about  p^th  of  an  inch  in 
diameter,  and  is  visible  to  the  naked  eye  as  a  minute  red  point.  At 
the  point  of  union  of  the  tubule  with  the  capsule,  it  presents  a  narrow 
portion,  called  the  neck,  beyond  which  the  tubule  becomes  convoluted 
for  a  considerable  distance,  forming  the  first  or  proximal  convoluted 
tube  (fig.  140,  2).  As  it  descends  towards  the  medullary  ray,  the 
tubule  becomes  nearly  straight,  but  having  a  slight  spiral  tendency  : 


592 


STKUCTURE   OF   THE   KIDNEY. 


this  portion  of  the  tube  is  termed  the  spiral  tubule  (Schachowa). 
The  tubule  now  enters  the  medullary  portion,  narrowing  very  sud- 
denly in  its  calibre,  and  descends  towards  the  apex  of  the  pyramid, 
constituting  the  descending  limb  of  Henle's  loop  (3).  The  tubule  here 
bends  upon  itself,  forming  a  loop,  the  loop  of  Henle,  and  ascends  to 


1.  Malpighian  capsule. 

2.  First  or  proximal  con- 

voluted tubule. 

2b.  Second  or  distal  con- 
voluted tubule. 

3.  Descending     limb     of 

Henle's  loop. 

(Between  2  and  3  the  tube 
is  called  the  spiral 
tubule  of  Schachowa.) 

4.  Ascending     limb      of 

Henle's  loop. 

5.  Irregular  tubule. 


FIG.  140. 


6.  Collecting  tube 

(Between  2  and  6  the  tube 
is  called  the  curved 
or  junctional  tubule.) 

6,  7,  8.  Different  portions 
of  the  collecting  or 
straight  tube. 

a.  Apex  of  pyramid. 

b.  Base  of  pyramid. 

c.  Cortical  portion. 


DIAGRAM   OP   THE   COURSE   AND   ARRANGEMENT   OF   THE    URI NIFEROUS   TUBES. 


re-enter  the  cortical  substance  as  the  ascending  limb  of  Henle's  loop 
(4),  which  is  larger  than  the  descending  limb.  On  passing  out  of  the 
medullary  ray  of  the  cortical  portion,  the  tubule  becomes  irregu- 
larly dilated,  and  takes  the  name  of  the  irregular  tubule  (5)  ;  this 
is  continued  on  into  another  convoluted  portion,  called  the  second  or 
distal  convoluted  tubule  (2b),  which,  before  entering  the  straight  tube, 


STRUCTURE    OF   THE    KIDNEY.  593 

becomes  much  narrowed  and  curved,  called  the  curved  or  junctional 
tubule.  We  have  thus  traced  the  straight  tubes  from  their  ter- 
mination at  the  papillae  to  their  commencement  at  the  pyramids  of 
Ferrein,  and  have  also  traced  the  convoluted  tubules  from  their 
origin  in  the  Malpighian  capsules  to  their  junction  with  the  com- 
mencement of  the  straight  tubes. 

The  tubuli  uriniferi  consist  of  a  basement  membrane  lined  with 
epithelium,  which  varies  in  the  different  parts  of  the  tubuli.  The 
capsule  is  lined  with  flattened  cells,  having  oval  nuclei ;  the  neck 
has  cubical  epithelium  ;  the  first  convoluted  tubule  is  lined  with 
polyhedral  epithelium,  presenting  numerous  rod-like  processes, 
resting  at  one  end  on  the  basement  membrane,  while  the  other 
extends  towards  the  lumen  of  the  tubule,1  and  thus  presents  the 
appearance  of  striation ;  the  spiral  tubule  of  Schachoiva  has  similar 
epithelium ;  the  descending  limb  is  lined  with  flattened  epithelium, 
like  that  in  the  capsule ;  the  ascending  limb  presents  epithelium 
similar  to  that  found  in  the  first  convoluted  and  spiral  portion  of 
the  tubule,  although  smaller  and  with  shorter  rod-like  processes  ; 
the  irregular  tubule  is  furnished  with  the  rod-like  cells  of  unequal 
length,  which,  however,  render  the  lumen  more  uniform ;  the  second 
convoluted  tubule  has  epithelium  somewhat  like  that  of  the  first 
convoluted  tubule,  but  having  long  cells  with  large  nuclei,  and 
possessing  high  refractive  properties  ;  the  curved  or  junctional  tiibide 
has  a  large  lumen,  and  is  lined  by  angular  or  fusiform  cells  with 
short  processes ;  the  collecting  or  straight  tubes  are  lined  with 
cubical  epithelium,  which  in  the  larger  tubes  becomes  distinctly 
columnar. 

The  renal  artery  enters  the  hilum  between  the  pelvis  and  the 
renal  vein.  It  shortly  divides  into  four  or  five  branches,  which 
pass  outwards  between  the  papillae,  and  then  enter  the  cortical 
portion  between  the  pyramids.  From  these  there  pass  to  each 
Malpighian  pyramid  two  branches,  which  ascend  along  its  sides  as 
far  as  its  base,  distributing  in  their  course  small  vessels  which  pass 
to  the  Malpighian  capsules.  At  the  base  of  the  pyramid  they 
form  arches,  and  make  a  bend  from  which  two  sets  of  branches 
are  given  off,  the  iuterlobular  arteries  and  the  arteriolas  rectae. 
1  Heidenhain,  Archiv  /.  mikr.  Anatom.  x.,  1873. 

Q  Q 


594 


STRUCTUKE    OF    THE    KIDNEY. 


a.  Artery. 

v.  Vein,  or  efferent  vessel. 

c.  Capsule. 

d.  Urinary  tube. 


The  interlobular  arteries  pass  off  at  right  angles  between  the 
medullary  rays,  and  then  run  amongst  the  convoluted  tubes,  some 
to  enter  the  Malpighian  capsules,  and  others  to 
reach  the  surface  and  supply  the  capsule,  ending 
in  the  stellate  veins  beneath  the  capsule.  The 
arteriole  which  passes  to  the  Malpighian  capsule 
is  termed  the  afferent  vessel,  and,  entering  the 
dilated  extremity  of  the  uriniferous  tube,  breaks 
up  into  a  number  of  convoluted  capillary  ves- 
sels, constituting  the  glomerulus  of  Malpighi. 
The  blood  is  returned  from  the  glomerulus  by 
a  small  efferent  vein,  which  emerges  from  the 
capsule  close  to  the  entrance  of  the  artery. 
This  vein,  after  a  short  course,  breaks  up,  like 
an  artery,  into  a  dense  network  of  capillaries, 
which  ramify  over  the  convoluted  tubules.  Some 
of  the  veins  from  the  lower  glomeruli  break  up 
into  straight  vessels,  and  then  pass  from  the  medullary  rays  into 
the  pyramid  (fig.  141). 

The  arteriolce  rectce  are  destined  for  the  supply  of  the  Malpi- 
ghian pyramids,  entering  them  at  their  bases,  and  then  pass  down- 
wards to  their  apices,  where  they  join  the  venous  plexuses. 

The  Malpighian  bodies  are  small  red  granular  masses  about 
i^o-th  of  an  inch  in  diameter,  and  are  only  found  in  the  cortical 
substance.  Each  is  composed  of  the  dilated  commencement  of  a 
uriniferous  tube  forming  the  Malpighian  capsule,  containing  within 
it  a  coil  of  small  blood-vessels  called  the  Malpighian  tuft  or  glomer- 
ulus. The  capsule  is  composed  of  a  homogeneous  membrane,  and 
is  pierced  by  a  small  artery,  afferent  vessel,  which  enters  it  oppo- 
site the  commencement  of  the  urinary  tubule.  In  the  capsule  the 
artery  breaks  up  into  a  coil  of  minute  blood-vessels,  glomerulus, 
and  returns  its  blood  by  a  vein,  efferent  vessel,  which  emerges  from 
the  capsule  close  to  where  the  artery  entered  (fig.  141).  The 
capillary  plexus  within  the  capsule  is  surrounded  by  the  epithe- 
lium lining  the  interior  of  the  capsule.1 

1  Histologists  differ  with  respect  to  the  disposition  of  the  epithelium  over  the 
glomerulus  :  some  assert  that  it  has  no  epithelial  covering,  but  that  it  hangs  loose 


STKUCTURE  OF  THE  SUPRA-RENAL  CAPSULES.        595 

The  renal  veins  return,  the  blood  from  three  sources :  from  the 
veins  situated  beneath  the  capsule  and  those  corresponding  to  the 
interlobular  arteries  which  pass  between  the  medullary  rays,  and 
at  the  bases  of  the  Malpighian  pyramids  join  the  venae  rectae  ;  the 
venae  rectae  return  the  blood  from  the  arteriola3  rectae,  and  begin 
in  plexuses  at  the  apices  of  the  pyramids,  they  then  pass  outwards 
between  the  tubuli  recti,  and  join  the  interlobular  veins  to  form 
the  proper  renal  veins;  these  pass  down  along  the  sides  of  the 
Malpighian  pyramids,  accompanied  by  their  corresponding  arteries, 
and  in  their  course  to  the  sinus  receive  the  efferent  veins  from  the 
adjacent  cortical  substance.  At  the  sinus  they  communicate  freely 
with  each  other  and  join  to  form  the  renal  vein. 

The  nerves,  about  fifteen  in  number,  forming  the  renal  plexus, 
are  derived  from  the  lesser  and  smallest  splanchnic  nerves,  the 
solar  plexus,  and  the  semilunar  ganglion. 

The  lymphatics,  consisting  of  a  deep  and  a  superficial  set,  pass 
to  the  lumbar  glands. 

SUPRA-RENAL  These  bodies,  situated  at  the  top  of  the  kidneys, 

CAPSULES.  belong  to  the  class  of  ductless  glands.     They  are 

of  yellow-ochre  colour:  the  right  is  triangular,  and  resembles  a 
•cocked  hat ;  the  left  is  more  almond-shaped  and  rather  the  larger 
of  the  two.  They  measure  about  an  inch  and  a  half  in  their  long 
diameter,  about  three-quarters  in  breadth,  and  two  or  three  lines 
in  thickness;  they  weigh  from  one  to  two  drachms.  The  gland 
is  surrounded  by  connective  tissue  and  fat,  and  is  invested  by  a 
thin  fibrous  covering,  which  sends  down  partitions  into  the  interior 
through  furrows  on  their  surface. 

A  perpendicular  section  shows  that  it  consists  of  a  firm  exterior 
or  cortical  part,  and  of  an  interior  or  medullary  substance,  soft  and 
pulpy. 

The  cortical  portion  is  of  a  yellow  colour  and  forms  the  principal 
part  of  the  organ.  It  consists  of  parallel  columns  arranged  per- 
pendicularly to  the  surface,  due  to  the  capsule  sending  processes 

within  the  capsule  ;  some,  that  the  tuft  is  completely  invested  with  epithelium, 
except  where  the  afferent  and  efferent  vessels  pass  in ;  others,  again,  that  only 
that  portion  of  the  glomerulus  which  looks  towards  the  neck  of  the  tubule  is 
covered  with  epithelium. 

Q  Q  2 


596        STRUCTURE  OF  THE  SUPRA-RENAL  CAPSULES. 

into  the  interior  of  the  gland,  which  communicate  at  frequent 
intervals  by  transverse  bands.  There  are  thus  formed  numerous 
spaces  which  communicate  with  each  other ;  the  spaces  at  the 
surface  are  smaller,  while  'those  towards  the  centre  are  longer ;  the 
section  through  the  cortex  gives  the  appearance  of  a  fine  network, 
the  external  portion  taking  the  name  of  the  zona  glomemdosa,  the 
internal  portion  that  of  the  zona  reticularis,  the  intermediate 
portion  that  of  the  zona  fasciculata.  The  reticular  tissue  is  made 
up  of  fibrous  tissue  with  longitudinal  bundles  of  unstriped  muscular 
tissue.  The  interspaces  are  occupied  by  granular,  polyhedral  cells, 
from  a  ^  Oth  to  yi^Vo^  °f  an  inch,  which  do  not  fill  the  spaces,  so 
that  between  them  and  the  walls  of  the  spaces  there  are  intervals, 
believed  to  be  spaces  which  communicate  with  the  lymphatics  in 
the  trabecular  tissue. 

The  medullary  portion  varies  in  colour  according  to  the  amount 
of  blood  contained  in  it,  being  sometimes  of  a  dark-brown  colour, 
sometimes  nearly. white.  Not  infrequently  the  medullary  part  is 
converted  into  a  cavity,  but  this  is  probably  a  post-mortem  change. 
It  consists  of  a  plexus  of  minute  veins,  supported  by  the  delicate 
areolar  tissue  containing  muscular  fibres,  and  presents  a  reticular 
aspect.  Among  these  are  numerous  granular  and  branched  cells.1 

The  arteries  to  the  gland  are  conveyed  along  the  trabecular 
tissue,  and,  after  supplying  the  gland-tissue,  converge  to  the 
centre,  where  the  blood  is  returned  into  the  venous  plexuses  in  the 
medullary  portion.  They  are  derived  from  the  abdominal  aorta,, 
the  phrenic  and  the  renal  arteries.  The  vein  begins  in  the  centre 
as  a  single  vessel,  and  joins,  on  the  right  side,  the  inferior  vena 
cava,  and  on  the  left  side  the  left  renal  vein. 

The  lymphatics  terminate  in  the  lumbar  glands. 

The  nerves  are  derived  from  the  solar  and  renal  plexuses,  and 
in  them  are  found  numerous  ganglia.  They  are  distributed  chiefly 
to  the  medullary  portion.2  Of  late  years  the  minute  structure  and 
functions  of  the  supra-renal  capsules  have  been  much  investigated, 

1  The  medullary  cells  are  stained  a  deep  brown  colour  on  the  addition  of 
bichromate  ofjpotash,  the  cortical  cells  being  scarcely  affected  by  it. 

2  Luschka  states  that  the  branched  granular  cells  of  the  medullary  portion 
are  connected  with  the  nerve-fibres. 


THE    STOMACH.  597 

in  consequence  of  the  discovery,  made  by  Dr.  Addison,  of  the  close 
relation  which  exists  between  certain  diseases  in  these  bodies  and 
a  brown  discoloration  of  the  skin.  Their  precise  function  is  still 
unknown. 

STOMACH  AND  The  alimentary  canal  is  composed  of  four  coats : 

INTESTINES.  a  serous,  a  muscular,  a  submucous,  and  a  mucous. 

First,  is  the  serous  or  peritoneal  coat,  described  at  p.  459.  Secondly, 
under  the  serous  is  a  muscular  coat,  upon  which  the  chief  strength 
of  the  canal  depends.  It  consists  of  two  distinct  strata  of  plain 
muscular  fibres ;  the  outer  stratum  is  longitudinal,  the  inner  cir- 
cular. This  arrangement  not  only  makes  the  bowel  stronger,  but 
regulates  its  peristaltic  action,  for  the  longitudinal  fibres,  by  their 
contraction,  tend  to  shorten  and  straighten  the  tube,  while  the 
circular  fibres  contract  upon  and  propel  its  contents  to  greater 
advantage.  Connecting  this  coat  and  the  mucous,  is  a  layer  of 
areolar  tissue  called  the  submucous  coat,  in  which  the  arteries 
break  up  before  entering  the  mucous  membrane.  The  mucous  is 
the  most  complicated  of  all  the  coats,  for  it  presents  different 
characters  in  different  parts,  according  to  the  functions  which  it 
has  to  perform. 

The  stomach  should  be  moderately  distended 
STOMACH.  ...  ,  .  ,  .  -..-,    '  ,  . 

to  see  its  size,  which  varies  in  different  subjects 

according  to  the  habits  of  the  individual.  When  distended,  an 
average  stomach  would  be  about  ten  or  twelve  inches  in  length, 
and  four  in  depth  and  width ;  its  weight  is  stated  to  be  about  four 
and  a  half  ounces.  It  is  conical  in  shape ;  the  left  part  forms  a 
large  bulge  called  the  cardiac  or  splenic  end ;  and  on  the  right  side 
where  the  food  passes  out,  it  becomes  small  and  contracted,  and  is 
called  the  pyloric  end.  The  stomach  presents  for  examination  two 
surfaces,  two  borders,  two  ends,  and  two  orifices. 

The  anterior  surface  is  convex,  and  looks  upwards  and  forwards; 
the  posterior  surface  looks  downwards  and  backwards. 

The  upper  border  or  the  lesser  curvature  is  concave  and  short, 
and  extends  from  the  oesophagus  to  the  pylorus ;  it  is  connected 
to  the  liver  by  the  gastro-hepatic  omentum.  The  lower  border  or 
the  greater  curvature  is  convex,  and  affords  attachment  to  the  great 
omentum. 


598  STRUCTURE  OF  THE  STOMACH. 

The  left  end  is  the  larger,  and  is  called  the  cardiac  or  splenic 
end ;  it  bulges  out  to  the  extent  of  two  or  three  inches  to  the  left 
of  the  entrance  of  the  oesophagus,  and  is  called  the  great  cul-de-sac 
or  fundus.  The  right  end  is  narrow,  and  makes  a  double  bend: 
near  the  first  it  bulges  into  a  pouch,  called  the  antrum  pylori,  or 
the  small  cul-de-sac. 

The  cesophageal  or  cardiac  orifice^  situated  at  the  highest  part  of 
the  stomach,  is  on  the  left,  and  receives  the  O3sophagus ;  the  pyloric 
orifice  is  continued  on  into  the  duodenum,  and  is  narrow,  being 
guarded  by  a  musculo-mucous  ring,  the  pylorus.1 

The  stomach  is  connected  at  its  borders  by  peritoneal  folds 
extending  to  neighbouring  structures :  thus,  its  lesser  curve  is  con- 
nected with  the  transverse  fissure  of  the  liver  by  the  gastro-hepatic 
or  lesser  omentum ;  its  cardiac  end  is  connected  with  the  hilum 
of  the  spleen  by  the  gastro-splenic  omentum ;  to  the  left  of  the 
O3sophagus  it  is  connected  with  the  diaphragm  by  the  gastro-phrenic 
ligament ;  to  its  greater  curve  is  attached  the  great  omentum, 
which  is  continuous  on  the  left  side  with  the  gastro-splenic  omentum. 

The  pylorus  is  the  narrow  circular  ring,  composed  of  circular 
muscular  fibres  and  mucous  membrane,  through  which  the  food 
passes  into  the  duodenum.  The  serous  and  longitudinal  muscular 
fibres  take  no  part  in  its  formation,  being  continued  over  it  on  to 
the  duodenum. 

The  stomach  consists  of  four  coats  :  serous,  muscular,  submucous 
and  mucous. 

The  serous  or  peritoneal  coat  covers  the  surface  of  the  stomach, 
except  at  the  borders  where  the  peritoneum  is  continued  as  omenta 
to  other  organs ;  it  is  along  these  borders  that  the  vessels  run. 

The  muscular  coat  can  be  seen  when  the  serous  coat  is  removed  > 
The  fibres  are  of  the  unstriped  variety,  and  arranged  in  three  layers  : 
an  external  or  longitudinal,  a  middle  or  circular,  and  an  internal 
or  oblique. 

1  The  position  of  the  stomach  within  the  abdomen  and  its  relations  with  sur- 
rounding structures  are  matters  of  much  dispute.  Dr.  Lesshaft  has  come  to  the 
conclusion  that  the  stomach  is  nearly  vertical,  so  that  its  fundus  touches  the 
diaphragm.  (See  Lancet,  March  11,  1882,  p.  406.)  His,  and  most  anatomists,  are 
of  opinion  that  the  long  axis  is  placed  obliquely  from  left  to  right  within  the, 
abdomen. 


STRUCTURE  OF  THE  STOMACH.  599 

The  longitudinal  fibres  are  continuous  with  the  longitudinal 
fibres  of  the  oesophagus,  and  spread  out  over  the  stomach,  being 
most  numerous  along  the  curvatures  of  the  stomach  :  they  are  at 
the  pyloric  end  continuous  with  the  longitudinal  fibres  of  the 
duodenum. 

The  circular  filrres  are  well-marked  about  the  middle  of  the 
stomach,  but  are  most  abundant  at  the  pylorus,  where  they  form 
a  powerful  sphincter. 

The  oblique  fibres  are  scattered  over  the  sides  of  the  stomach, 
and  are  most  distinct  at  the  entrance  of  the  oesophagus,  crossing 
obliquely  from  left  to  right  and  from  right  to  left.  They  are  con- 
tinuous with  the  well-marked  circular  fibres  of  the  oesophagus. 

The  submucous  coat  serves  to  connect  the  muscular  with  the 
mucous  coats.  It  consists  of  areolar  tissue,  and  permits  the 
muscular  and  mucous  coats  to  move  freely  on  each  other,  and 
allows  the  blood-vessels  to  ramify  minutely  before  they  enter  the 
mucous  membrane. 

When  the  stomach  is  laid  open  from  the  cesophageal  to  the 
pyloric  orifice,  the  mucous  membrane  is  seen  to  be  thick,  of  pale 
pink  or  straw  colour,  and  is  gathered  into  longitudinal  folds — rugce 
— which  disappear  when  the  stomach  is  distended. 

If  a  portion  of  the  mucous  membrane  be  examined  under  the 
microscope,  its  surface  will  be  seen  to  be  mapped  out  into  small 
hexagonal  pits  or  alveoli,  surrounded  by  ridges,  giving  it  a  honey- 
combed appearance.  The  pits  vary  from  j-J-^th  to  ^-Q-th  of  an 
inch  in  diameter.  At  the  bottom  of  them  are  a  number  of  minute 
apertures,  the  orifices  of  the  gastric  follicles.  In  a  perpendicular 
section,  the  follicles  are  arranged  in  parallel  lines  at  right  angles 
to  the  surface,  and  terminate  in  blind  sacculated  ends  set  in  the 
submucous  tissue.  The  entire  thickness  of  the  mucous  membrane 
is  made  up  of  these  tubular  glands.  The  follicles  consist  of  two 
kinds,  mucous  and  peptic  glands.  Tubular  in  shape,  they  have  a 
basement  membrane  lined  with  epithelium,  and  average  about  -^th 
of  an  inch  long,  and  -j-Jpoth  of  an  inch  in  diameter.  The  mucous 
glands  are  found  over  the  whole  surface,  but  are  most  numerous  at 
the  pyloric  end  of  the  stomach.  They  are  composed  of  tubes,  each 
consisting  of  two  or  three  short  tubules,  opening  into  a  common 


600  STRUCTURE  OF  THE  STOMACH. 

duct,  which  itself  opens  into  the  bottom  of  an  alveolus.  They  are 
lined  with  columnar  epithelium  continuous  with  that  lining  the 
mucous  membrane.  The  peptic  glands  are  also  found  over  the 
entire  surface  of  the  mucous  membrane,  and  consist  of  tubules  with 
branched  csecal  extremities  opening  into  a  common  duct,  which  is, 
however,  shorter  than  that  of  a  mucous  gland.  They  are  lined  with 
columnar  epithelial  cells,  called  the  central  cells,  and  are  supposed  to 
be  concerned  in  the  secretion  of  the  gastric  juice;  these  cells  become, 
at  the  neck  of  the  gland,  much  shorter  and  more  granular.  The 
lumen  of  the  gland  is  very  small,  but  is  somewhat  larger  at  the  free 
and  the  cascal  ends  than  in  the  middle.  Towards  the  lower  part  or 
fundus  of  the  gland  there  are  found  spheroidal  and  granular  cells 
between  the  epithelium  and  the  basement  membrane,  called  parietal 
cells. 

In  the  stomachs  of  young  children  there  is  a  large  amount  of 
lymphoid  tissue  found  between  the  gastric  glands.  It  is  aggre- 
gated into  small  masses  in  the  mucous  membrane,  and  resembles 
in  many  respects  the  solitary  glands  of  the  intestine,  although  not 
so  well  defined. 

The  mucous  membrane  of  the  stomach  is  lined  by  columnar 
epithelium,  which  also  extends  into  the  glands.  A  thin  layer  of 
unstriped  muscular  tissue  (musctflaris  mucosee)  is  found  between 
the  mucous  membrane  and  its  submucous  tissue,  varying  in  amount 
and  in  the  number  of  its  layers. 

The  glands  of  the  stomach  are  richly  supplied  with  blood,  which 
is  derived  from  the  gastric,  the  vasa  brevia,  the  right  and  left  gastro- 
epiploica,  and  the  pyloric  arteries.  The  arteries  form  a  stratum  of 
minute  inosculations  in  the  submucous  tissue,  in  which  the  closed 
ends  of  the  tubes  are  set ;  from  this  stratum,  the  capillary  plexuses 
run  up  between  the  tubes  to  the  surface  of  the  stomach,  where 
they  again  form  a  larger  capillary  plexus  and  form  the  hexagonal 
spaces  before  alluded  to.  The  veins,  corresponding  to  the  pyloric 
and  gastric  arteries,  end  in  the  vena  portse ;  those  corresponding  with 
the  vasa  brevia  and  the  epiploic  arteries  open  into  the  splenic  vein. 

The  lymphatics  enter  the  glands  along  the  lesser  and  greater 
curvatures  of  the  stomach,  and  may  be  divided  into  a  superficial 
and  a  deep  set. 


STRUCTURE  OF  THE  SMALL  INTESTINE.          601 

The  nerves  are  derived  from  the  pneumogastrie  nerves  and  from 
the  solar  plexus. 

SMALL  The  small  intestine,  consisting  of  the  duodenum, 

INTESTINE.  jejunum,  and  ileum,  forms  a  tube  averaging  twenty 

feet  in  length,  which  gradually  lessens  in  calibre  until  it  opens  into 
the  caecum.  The  duodenum  is  about  twelve  fingers'  breadth  in 
length  (whence  its  name) ;  the  jejunum  l  comprises  two-fifths,  the 
ileum 2  three-fifths,  of  the  remaining  part  of  the  small  intestine. 
As  regards  their  external  characters,  the  duodenum  and  jejunum 
are  more  vascular  than  the  ileum,  and  feel  thicker  in  consequence 
of  the  peculiar  arrangement  of  their  mucous  membrane  ;  but  there 
are  no  defined  limits  between  the  different  portions  of  the  intestinal 
canal. 

Its  coats  are  four  in  number :  serous,  muscular,  submucous,  and 
mucous. 

The  serous  coat  consists  of  peritoneum,  and  forms  a  complete 
investment,  except  in  the  case  of  the  descending  and  transverse 
portions  of  the  duodenum,  which  are  only  covered  in  front. 

The  muscular  coat  consists  of  an  outer  longitudinal  layer  and 
an  inner  circular  thicker  layer,  which,  however,  becomes  thinner 
towards  the  end  of  the  ileum. 

The  submucous  coat  connects  the  muscular  and  mucous  coats ; 
immediately  beneath  the  mucous  membrane  there  is  a  very  thin 
layer  of  non-striped  muscular  fibres,  termed  muscularis  mucosce. 

The  mucous  coat  can  only  be  seen  when  the  intestine  is  cut 
open  from  the  upper  end,  and  is  composed  of  the  following  strata : 
the  muscularis  mucosae,  a  layer  of  retiform  tissue  with  lymph 
corpuscles,  with  blood-vessels  and  nerves ;  and,  lastly,  a  layer  of 
•columnar  epithelium. 

When  the  intestine  is  laid  open  we  see  that  the  mucous  mem- 
brane is  arranged  in  close  transverse  folds,  called  valvulce  conni- 
ventes  or  valves  of  Kerkring.  These  differ  from  other  folds  in  the 
alimentary  canal — e.g.  in  the  oesophagus  and  stomach — in  that  they 
are  not  obliterated  when  the  tube  is  distended.  Each  fold  extends 
about  one-half  or  two-thirds  round  the  intestine,  but  they  are  not 
all  of  equal  size,  and  are  about  one-third  of  an  inch  in  depth.  They 
1  Ftoaijejunus,  empty.  2  From  tfattv,  to  roll  or  twist. 


602  STRUCTURE  OF  THE  SMALL  INTESTINE. 

commence  immediately  below  the  opening  of  the  biliary  and  pan- 
creatic ducts,  and  are  most  developed  in  the  duodenum  and  the 
upper  part  of  the  jejunum.  Below  this  part  of  the  tube  they 
gradually  decrease  in  size,  and  become  wider  apart,  till  they  finally 
disappear  near  the  middle  of  the  ileum.  The  use  of  the  valvulas 
conniventes  is  to  increase  the  extent  of  surface  for  the  absorption 
of  chyle;  to  prevent  the  food  passing  too  rapidly  through  the 
intestine,  and  for  secretion. 

If  a  portion  of  small  intestine  be  washed  and  placed  in  water, 
the  surface  of  the  mucous  membrane  appears  like  the  soft  fur  or 
pile  upon  velvet.  This  appearance  is  produced  by  small  processes 
called"  villi.  These  are  extremely  vascular  projections  of  the 
mucous  membrane,  about  a  fourth  of  a  line  in  length,  and  are 
so  numerous  that  a  square  line  contains  from  forty  to  ninety  of 
them.1  Their  size,  however,  and  their  number,  bear  a  direct  ratio 
to  those  of  the  valvulse  conniventes.  Under  the  microscope  a  villus 
is  seen  to  consist  of  an  outstanding  process  of  the  mucous  mem- 
brane, covered  by  a  layer  of  columnar  epithelium,  which  rests  upon 
a  basement  membrane.  Each  villus  is  furnished  with  an  artery 
which  forms  a  network  of  inosculations  in  it,  and  then  returns  its 
blood  by  a  single  vein.  Down  its  middle  runs  a  lacteal  or  absorb- 
ing vessel,  which  commences  in  a  closed  end  near  the  summit  of 
the  villus,  where  it  is  surrounded  by  a  layer  of  pale  non-striped 
muscular  fibres  proceeding  from  the  muscularis  mucosee.  This 
is  surrounded  by  a  plexus  of  capillaries,  external  to  which  is  the 
basement  membrane  supporting  columnar  epithelium.  Forming 
the  matrix  of  the  villus  is  a  fine  network  enclosing  large  flattened 
cells  with  oval  nuclei  and  lymph  cells. 

INTESTINAL  There  are  four  kinds  of  glands 2  in  the  small  in- 

GLANDS.  testine,  called  the  glands  of  Lieberkiihn,  Brunner, 

Peyer,  and  the  solitary  glands.  The  first  and  last  are  distributed 
over  the  whole  tract  of  the  intestinal  mucous  membrane ;  the  other 
two  over  particular  parts. 

1  Krause  estimates  the  total  number  of  villi  at  four  millions. 

''  A  satisfactory  examination  of  the  intestinal  glands  can  be  made  only  in 
specimens  quite  recent,  taken  from  young  persons  who  have  died  suddenly,  or 
from  a  rapidly  fatal  disease. 


STRUCTURE  OF  THE  SMALL  INTESTINE.  603 

The  simple  follicles  or  crypts  of  Lieberlcuhn,1  the  most  numerous 
of  all,  are  minute  tubes  with  blind  ends,  very  thickly  distributed 
over  the  small  and  the  large  intestines.  Under  the  microscope, 
their  orifices  are  seen  between  the  villi,  like  so  many  minute  dots. 
They  vary  in  depth  from  -J^-th  to  ^th  of  a  line,  and  about  ^kh  of 
a  line  in  diameter ;  their  walls  consist  of  a  delicate  basement  or 
endothelial  membrane,  and  are  lined  with  columnar  epithelium. 

The  duodenal  or  glands  of  Brunner 2  are  found  only  in  the  duo- 
denum and  a  small  part  of  the  beginning  of  the  jejunum.  They 
are  just  visible  to  the  naked  eye,  and  may  be  seen  by  removing 
the  muscular  coat.  Their  structure  exactly  resembles  the  round 
compound  glands  of  the  mucous  membrane  of  the  mouth. 

The  glands  of  Peyer 3  (glandulce  agminatce)  abound  most  in  the 
ileum,  and  are  seen  most  distinctly  in  children.  They  are  arranged 
in  groups,  from  twenty  to  forty  in  number,  on  that  part  of  the  in- 
testine most  distant  from  the  attachment  of  the  mesentery.  These 
groups  are  from  half  an  inch  to  three  inches  long,  of  an  oval  form, 
and  increase  in  size  and  number  towards  the  lower  part  of  the 
ileum.  If  a  group  be  examined  by  dissecting  away  the  muscular 
coat,  you  find  that  it  is  composed  of  a  number  of  small  oval  vesicles, 
like  Florence  flasks,  imbedded  in  the  submucous  tissue.  They 
are  composed  of  masses  of  lymphoid  tissue,  of  about  three-fourths 
of  a  line  in  diameter,  and  contain  an  opaque  greyish  fluid.  No 
excretory  ducts  have  been  traced  from  these  vesicles,  but  they  are 
supposed  to  discharge  their  contents  by  rupture  of  their  capsules. 
Between  the  vesicles  are  found  Lieberkiihn's  follicles  ;  and  the  sur- 
face of  the  patches  is  covered  with  villi.  These  glands  are  liable 
to  be  ulcerated  in  typhoid  fever.  They  diminish  in  number  and 
size  with  old  age. 

The  solitary  glands  are  scattered  over  all  parts  of  the  small  and 
large  intestines.  They  consist  of  the  same  lymphoid  structure  as- 
the  glands  of  Peyer,  and  only  differ  from  them  in  being  solitary 
instead  of  being  aggregated  into  groups. 

1  J.  N.  Lieberkiihn,  Diss.  de  Fabric,  et  Actione  Villorum  Intestin.  ten.,  1782. 

2  J.  C.  Brunner,  Gland.  Duoden.  sen  Pancreas  Secundarium,  1715. 

3  Peyer,  De  Glandulis  Intestinorum,  1682.     These  glands  were  first  described 
by  Neheniiah  Grew,  in  1681. 


•604  STRUCTURE   OF   THE   LARGE   INTESTINE. 

The  lymphatics  consist  of  two  sets — those  of  the  muscular,  and 
those  of  the  mucous  coats ;  the  latter  receive  those  from  the  villi, 
at  the  base  of  which  they  form  a  minute  plexus,  and,  after  piercing 
the  muscular  coat,  join  with  the  former,  which  are  chiefly  found 
between  the  longitudinal  and  the  circular  layers  of  muscular  fibres. 

The  nerves  are  derived  from  the  superior  mesenteric  plexus,  and 
accompany  the  superior  mesenteric  artery  and  its  branches,  between 
the  layers  of  the  mesentery;  after  reaching  the  intestinal  walls 
the  nerve-filaments  separate  from  the  arteries.  They  then  pierce 
the  external  longitudinal  muscular  fibres,  and  form  a  very  minute 
gangliated  plexus — Auerliaclis  plexus  or  plexus  mesentericus — which 
distributes  filaments  to  the  muscular  layer  of  the  entire  intestinal 
•canal.  From  this  plexus  numerous  branches  perforate  the  internal 
•circular  muscular  layer,  and  unite  to  form  a  largely  gangliated 
plexus — Meissner's  plexus — in  the  submucous  tissue.  The  inter- 
muscular  plexus  probably  supplies  the  muscular  coat  and  regulates 
the  peristaltic  action  of  the  bowel ;  the  submucous  plexus  determines 
the  calibre  of  the  blood-vessels. 

LARGE  The  principal  external  characters  of  the  large 

INTESTINE.  intestine  are  that  it  is  pouched  or  sacculated,  and 

that  it  has  attached  to  it  little  pendulous  portions  of  fat  covered  by 
peritoneum,  called  appendices  epiploicce.  The  pouches  (sacculi)  are 
produced  by  a  shortening  of  the  longitudinal  muscular  fibres,  and 
by  their  being  collected  into  three  bands,  about  half  an  inch  wide, 
nearly  equidistant  from  each  other.  One  of  these  bands  corre- 
sponds with  the  attached  part  of  the  circumference  of  the  bowel ; 
another  with  the  front  part ;  a  third  with  its  concavity.  If  at  any 
given  part  the  three  bands  be  divided,  the  pouches  immediately 
disappear. 

In  a  colon  moderately  distended  and  dried,  we  observe  that  the 
mucous  membrane  forms  numerous  ridges  or  incomplete  septa  (see 
fig.  142) :  they  correspond  to  the  grooves  on  the  external  surface 
of  the  bowel,  and  disappear,  like  the  sacculi,  when  the  longitudinal 
bands  are  divided. 

The  rectum  differs  from  the  rest  of  the  large  intestine  in  that 
its  longitudinal  muscular  fibres  are  not  collected  into  bands,  but 
•distributed  equally  over  its  whole  circumference.  Moreover,  both 
the  longitudinal  and  circular  fibres  are  of  considerable  strength,  like 


STRUCTURE  OF  THE  LARGE  INTESTINE. 


605 


those  of  the  oesophagus,  as  one  might  expect  from  the  particular 
functions  which  these  parts  of  the  alimentary  canal  have  to  perform. 
For  an  inch  and  a  half,  or  thereabouts,  above  the  anus,  the  circular 
fibres  are  remarkably  developed,  and  constitute  the  internal  sphincter 


am. 


The  mucous  membrane  of  the  large  intestine  differs  considerably 
from  that  of  the  small.     There  are  neither  valvulse  conniventes  nor 


1.  Ileum. 

2.  Csecumorcaput'COli. 


3.  Appendix    vermi- 
formis. 


SECTION    THKOUGH    THE    JUNCTION    OF    THE    LARGE    AND    SMALL    INTESTINE,    TO 
SHOW    THE    ILEO-C-ECAL    VALVE. 

villi,  but  the  glands  of  Lieberkiihn  and  the  lymphoid  follicles  may 
i  be  seen  studding  the  mucous  membrane.  The  follicles  are  more 
abundant  in  the  caecum  and  in  the  appendix  vermiformis  than  in 
any  other  part  of  the  alimentary  canal.  The  blood-vessels  present 
the  same  hexagonal  arrangement  on  the  surface  as  that  of  the 
stomach.  That  the  mucous  membrane  of  the  large  intestine  may 
be  temporarily  used  as  a  substitute  for  the  stomach  is  proved  by 
the  fact  of  persons  having  been  nourished  for  many  weeks  solely 
by  injections.  The  mucous  membrane  is  lined  throughout  with 
columnar  epithelium. 

ILEO-C,ECAL  At   the  junction  of  the   small  with  the  large 

VALVE,  intestine  the  mucous  membrane  is  folded  so  as  to 


606  STRUCTURE  OF  THE  LARGE  INTESTINE. 

form  a  valve  :  but  it  is  not  a  perfect  one,  as  is  proved  by  pouring 
water  into  the  large  intestine,  or  by  the  occasional  vomiting  of  in- 
jections. The  arrangement  of  the  valve  is  best  examined  in  a  dried 
preparation.  The  opening  is  a  transverse  fissure  like  a  button- 
hole ;  and  the  two  flaps  are  arranged  like  an  upper  and  a  lower 
eyelid.  The  upper  lid  of  the  valve  projects  more  than  the  lower, 
so  that  the  contents  of  the  ileum  drop  naturally  down  into  the  caput 
coli,  where  they  are  apt  to  collect  and  form  hard  lumps.  The  flaps 
of  the  valve  consist  of  mucous  membrane  and  the  circular  fibres 
of  the  ileum.  The  longitudinal  fibres  of  the  ileum  are  continued 
directly  on  to  the  caecum :  if  these  be  divided,  the  ileum  can  be 
drawn  out,  and  the  valve  disappears.1 

FOLDS  IN  THE  In  many  subjects  we  observe  that  transverse  or 

BECTUM.  oblique  folds  of  the  mucous  membrane  project  into 

the  rectum.  These  cannot  be  seen  to  advantage  unless  the  bowel 
be  hardened  by  alcohol  in  its  natural  position.  Three,  more  pro- 
minent than  the  rest,  and  half  an  inch,  or  thereabouts,  in  width, 
were  first  pointed  out  by  Mr.  Houston.2  One  projects  from  the 
upper  part  of  the  rectum,  opposite  the  prostate  gland ;  another  is 
situated  higher  up,  on  the  side  of  the  bowel ;  while  the  third  is 
still  higher.  When  thickened  or  ulcerated,  these  folds  are  apt  to 
occasion  great  pain  and  obstruction  in  defaecation. 

AKTEKIAL  ^6  Present  opportunity  is  the  best  for  review- 

SUPPLY  OF  THE  ing  the  arterial  supply  of,  and  the  anastomoses 
ALIMENTARY  round,  the  alimentary  canal,  from  the  mouth  to 

the  anus.     Part  of  the  blood  supply  has  been  ex- 
amined in  the  dissection  of  the  head  and  neck ;  part  in  the  dis- 
section of  the  oesophagus  as  it  passes  through  the  thorax  ;  and  the* 
remainder  in  that  of  the  abdomen.     The  following  table  represents 
the  arteries  in  their  order,  beginning  at  the  mouth : — 

LOWER  LIP Submental  (deep  branch). 

Mental. 
Inferior  labial. 
Inferior  coronary. 

1  It  is  interesting  to  note  that  the  surface  of  the  valve,  towards  the  ileum,  is 
covered  with  villi ;  not  so  the  surface  towards  the  large  intestine. 

2  Dublin  Hospital  Reports,  vol.  v.  p.  163. 


ARTERIAL    SUPPLY    OF   THE    ALIMENTARY    CANAL. 


607 


UPPER  LIP 

CHEEK 


MOUTH,  ROOF  OF  ... 


MOUTH,  FLOOR  OF,  AND 
TONGUE 


EPIGLOTTIS 
PHARYNX 


(ESOPHAGUS,  CERVICAL  . 
(ESOPHAGUS,  THORACIC  . 

(ESOPHAGUS,  ABDOMINAL 
STOMACH . 


DUODENUM 


Superior  coronary. 

Buccal. 

Superior  coronary  (slightly). 

Facial. 

Transverse  facial. 

Infra- orbital. 

Superior  alveolar. 

Descending  palatine. 

Ascending  palatine. 

Pharyngeal  br.  of  ascending  pharyngeal. 

Artery  of  the  fnenum. 
Ranine. 
Sublingual. 
Dorsales  linguse. 
Tonsillar. 

Ascending  palatine. 
Ascending  pharyngeal. 

Superior  laryngeal  artery. 

Pterygo-palatine. 

Branches  of  ascending  pharyngeal. 
Branches  of  ascending  palatine. 
Superior  thyroid. 

Superior  thyroid. 
Inferior  thyroid. 

Inferior  thyroid. 
Thoracic  aorta. 
Gastric. 
Left  phrenic. 

Gastric. 
Left  phrenic. 

Gastric. 
Pyloric. 

Gastro-epiploica  dextra. 
Gastro-epiploica  sinistra. 
Yasa  brevia. 
Gastro-duodenalis. 

Pancreatico-duodenalis  superior. 
Pancreatico-duodenalis  inferior. 


608  ARTERIAL    SUPPLY    OF   THE    ALIMENTARY    CANAL. 

JEJUNUM Superior  mesenteric. 

ILEUM Superior  mesenteric. 

C^CUM Colic  br.  of  ileo-colic. 

ASCENDING  COLON      .  Colica  dextra. 

TRANSVERSE  COLON     .  Colica  media. 

DESCENDING  COLON     .  Colica  sinistra. 

SIGMOID  FLEXURE  .     .  Sigmoid  arteries. 

RECTUM Superior  hsemorrhoidal  (inferior  mesenteric). 

Middle  hsemorrhoidal  (internal  iliac). 
Inferior  hsemorrhoidal  (internal  pudic). 
Arteria  sacra  media. 


609 


DISSECTION  OF  THE  LOWER  EXTREMITY. 

THE  body  must  be  placed  on  its  back,  with  a  block  placed  beneath  the 
buttocks,  and  the  thigh  should  then  be  slightly  flexed  and  abducted. 
SURFACE  The  student,  before  commencing  to  reflect  the 

MARKING.  skin,  should  notice  the  irregularities  of  the  surface 

which  are  produced  by  subjacent  structures.  The  upper  part  of 
the  thigh  is  marked  off  from  the  abdomen  by  a  more  or  less  well- 
marked  curved  furrow,  having  its  convexity  downwards.  This 
furrow  corresponds  with  Poupart's  ligament,  which  is  attached 
externally  to  the  anterior  superior  iliac  spine,  and  internally  to 
the  spine  of  the  os  pubis.  The  spine  of  the  os  pubis  can,  even  in 
the  fattest  subject,  be  distinctly  felt,  and  is  a  very  valuable  land- 
mark in  the  diagnosis  between  an  inguinal  and  a  femoral  hernia  ; 
for  the  aperture  through  which  an  inguinal  hernia  emerges  is  the 
external  abdominal  ring,  situated  above  the  spine ;  the  aperture 
through  which  a  femoral  hernia  comes  out  is  the  saphenous  open- 
ing, situated  outside  the  spine.  In  front  of  the  thigh  is  a  large 
triangular  depression  corresponding  with  Scarpa's  triangle,  which 
has  its  base  at.  Poupart's  ligament.  This  depression,  which  is 
best  seen  in  thin  subjects,  contains  the  large  vessels  and  nerves 
passing  down  to  the  leg,  the  femoral  artery  being  nearly  in  the 
centre  of  the  space  :  a  furrow  indicating  the  course  of  these  vessels 
may  be  observed  extending  obliquely  down  the  inner  side  of  the 
thigh.  About  three  or  four  inches  below  the  anterior  superior 
iliac  spine,  there  is  seen  on  the  outer  side  of  the  thigh  the  well- 
marked  prominence  of  the  great  trochanter,  which  is  nearly  on 
the  same  level  as  the  spine  of  the  os  pubis.  The  sartorius  can  be 
seen  passing  obliquely  inwards  from  the  iliac  spine,  and  crossing 
over  the  femoral  vessels  about  four  inches  below  Poupart's  ligament ; 
in  the  latter  two-thirds  of  its  course  it  descends  nearly  vertically. 

R  R 


610  SUPERFICIAL   FASCIA   OF   THE   GROIN. 

The  well-defined  ridge,  extending  from  the  os  pubis  to  the  middle  of 
the  femur,  when  the  thigh  is  abducted,  is  caused  by  the  adductor 
longus  muscle. 

The  prominence  in  front  of  the  knee  is  produced  by  the  patella, 
to  which  is  attached  above,  the  tendon  of  the  quadriceps  muscle, 
and  below,  the  ligamentum  patellae,  both  of  which  can  be  distinctly 
felt.  On  each  side  of  the  patella  is  a  deep  depression,  which  leads 
on  the  outer  side  to  a  rounded  prominence,  the  external  condyle  ; 
and  on  the  inner  to  the  internal  condyle,  the  latter  being  the 
larger.  The  synovial  membrane  which  lines  the  knee-joint  usually 
extends  about  two  fingers'  breadth  above  the  patella,  and  is  a  little 
higher  on  the  inner  than  on  the  outer  side  of  the  joint. 

An  incision  should  be  made  along  the  groin,  extending  from 
the  anterior  superior  spine  of  the  ilium  to  the  spine  of  the  os  pubis ; 
another,  from  the  middle  of  the  first  down  the  front  of  the  thigh 
for  about  six  inches.  The  skin  only  should  be  reflected,  outwards 
and  inwards,  when  the  superficial  fascia  will  be  exposed. 

SUPERFICIAL  The  superficial  fascia  varies    in  thickness,  ac- 

FASCIA.  cording  to  the  condition  of  the  body.     Like  other 

superficial  fasciae,  it  is  divisible  into  two  or  more  layers,  be- 
tween which  are  situated  the  inguinal  glands  and  the  cutaneous 
vessels  and  nerves.  The  superficial  layer  is  continuous  with  that 
of  the  abdomen,  and  becomes  firmer  below  Poupart's  ligament,  to 
which,  however,  it  is  not  connected ;  the  deeper  layer  is  best 
marked  in  the  upper  part  of  the  thigh,  especially  where  it  stretches 
across  the  saphenous  opening,  to  the  margins  of  which  it  is  closely 
attached ;  this  portion  is  called  the  cribriform  fascia,  and  is  pro- 
truded forwards  by  a  femoral  hernia,  forming  one  of  its  coverings  ; 
this  layer  is  also  attached  to  Poupart's  ligament. 

The  superficial  layer  of  this  fascia  should  now  be  reflected,  by 
searching  for  one  of  the  subcutaneous  veins  (the  internal  saphena 
will  do)  which  run  between  the  upper  and  the  deeper  layers  of  the 
fascia.  The  cutaneous  vessels  can  thus  be  traced,  and  come  from 
the  common  femoral  artery  ;  they  are  three  in  number,  the  super- 
ficial epigastric,  the  superficial  external  pudic,  and  the  superficial 
circumflexa  ilii  arteries.  The  first  ascends  over  Poupart's  ligament 
to  the  abdomen  (p.  612)  ;  the  second  crosses  inwards  towards  the 


SUPERFICIAL   ARTERIES   OF   THE   GROIN.  611 

ps  pubis;  the  third  passes  outwards  to  the  ilium.  Each  artery  is 
accompanied  by  one,  sometimes  by  two  veins,  which  empty  them- 
selves, either  directly  into  the  femoral,  or  into  the  great  cutaneous 
vein  of  the  thigh,  called  the  saphena. 

SUPERFICIAL  These    glands    are    easily  recognised,   by  their 

INGUINAL  oval  form  and  reddish-brown  colour.     There  are 

GLANDS.  ^wo  ge£g .  one  gQ^  runs  parallel  to  Poupart's  liga- 

ment, and  receives  the  lymphatics  from  the  skin  of  the  penis,  the 
scrotum,  the  perineum,  the  anus,  the  buttock,  the  lower  part  of 
the  abdominal  wall,  and  the  upper  and  outer  aspect  of  the  thigh ; 
the  outer  and  lower  set  lies  along  the  saphena  vein,  chiefly  around 
the  saphenous  opening,  and  receives  the  lymphatics  frdm  the  foot, 
the  leg,  and  the  lower  part  of  the  thigh.  This  explains  why  in 
cancer  of  the  scrotum  and  syphilitic  disease  of  the  penis  the  first 
set  becomes  enlarged ;  and  the  second,  in  diseases  of  the  lower  ex- 
tremity. The  lymphatic  vessels  which  pass  to  and  from  the  glands 
are  small,  and  may  escape  observation,  unless  specially  looked  for. 
They  all  pass  through  the  femoral  ring  into  the  abdomen,  and 
eventually  empty  themselves  into  the  receptaculum  chyli. 

The  glands  mentioned  in  the  preceding  paragraph  are  all  super- 
ficial. There  are  others,  more  deeply  seated,  close  to  the  great 
vessels  of  the  thigh  :  these  are  much  smaller,  and  sometimes  cannot 
be  found. 

SUPERFICIAL  The  superficial  epigastric  artery  comes  through 

ARTERIES  OF  the  fascia  lata,  sometimes  through  the  saphenous 

THE  GROIN.  opening,  half  an  inch  below  Poupart's  ligament. 

It  ascends  over  Poupart's  ligament  to  pass  to  the  subcutaneous 
tissue  of  the  abdomen,  as  high  as  the  umbilicus,  and  supplies  the 
inguinal  glands,  and  anastomoses  with  the  deep  epigastric  and 
internal  mammary  arteries.  Its  further  course  is  described  at 
p.  423. 

The  superficial  circumfiexa  ilii  emerges  through  the  fascia  lata, 
runs  parallel  to  Poupart's  ligament  towards  the  crest  of  the  ilium, 
and  ends  in  the  subcutaneous  tissue  and  inguinal  glands.  It 
anastomoses  with  the  deep  circumflex  iliac,  the  gluteal,  and  the 
ascending  branches  of  the  external  circumflex  arteries. 

The  superficial  external  pudic    comes   through  th<^  saphenous 

B   R   2 


612 


SUPERFICIAL   ARTERIES    OF   THE    GROIN. 


opening,  crosses  over  the  spermatic  cord,  and  supplies  the  penis 
and  scrotum  in  the  male,  and  the  labium  in  the  female.  This 
artery  is  usually  divided  in  the  operation  for  femoral  hernia  ;  also 
in  that  for  phymosis,  since  it  runs  along  the  penis  to  supply  the 


FIG.  143. 


SUPERFICIAL    VESSELS    AND    GLANDS    OF    THE    GROIN.       SAPHENOUS    OPENING    WITH 
THE    CRIBRIFORM    FASCIA. 


1.  Saphenous  opening  of  the  fascia  lata. 

2.  Saphena  vein. 

3.  Superficial  epigastric  artery. 

4.  Superficial  circumflexa  ilii  artery. 


5.  Superficial  pudic  artery. 

6.  External  abdominal  ring. 

7.  Fascia  lata  of  the  thigh. 


prepuce.  Arising  directly  from  so  large  an  artery  as  the  femoral, 
it  sometimes  bleeds  profusely ;  for  it  is  an  admitted  fact  that  when 
even  a  small  branch,  coming  directly  from  a  principal  artery,  is 
divided  near  its  origin,  it  will  sometimes  pour  out  as  much  blood 
as  if  an  opening  were  punched  out  of  the  trunk  as  large  as  the 


INTERNAL  SAPHENA  VEIN.  613 

'area  of  the  divided  branch.1  There  is  another  pudic  artery,  called 
the  deep  or  inferior  external  pudic  :  this  runs  between  the  fascia 
lata  and  the  pectineus,  supplying  that  muscle,  the  scrotum  in  the 
male,  and  the  labium  in  the  female.  They  both  anastomose  with 
branches  of  the  internal  pudic  artery. 

The  incision  should  be  prolonged  down  the  thigh,  over  the 
knee  to  the  tubercle  of  the  tibia.  The  skin  must  then  be  reflected, 
to  expose  the  subcutaneous  tissue  over  the  whole  of  the  front  of 
the  thigh.  The  cutaneous  vessels  and  nerves  should  be  looked  for 
in  the  subcutaneous  fat  in  the  following  situations :  on  the  inner 
side  are  the  inguinal  branch  of  the  ilio-inguinal  nerve  passing  down 
through  the  external  abdominal  ring,  internal  to  the  saphenous 
opening ;  lower  down,  are  the  two  branches  of  the  internal  cutaneous 
nerve  supplying  the  skin  on  the  inner  aspect  of  the  thigh  as  far  as 
the  knee,  the  lower  branch  accompanying  the  internal  saphena  vein 
which  ascends  to  pierce  the  saphenous  opening ;  there  are  also  low 
down  some  filaments  from  the  long  saphena  nerve ;  on  the  front  of 
the  thigh  there  is  found  the  crural  branch  of  the  genito-crural  nerve, 
and  lower  down,  as  far  as  the  knee  are  the  middle  cutaneous  nerves  ; 
on  the  outer  side  are  seen  filaments  of  the  external  cutaneous  nerve. 
INTEBNAL  This  is  the  chief  subcutaneous  vein  of  the  lower 

SAPHENA  limb.     Its  roots,  arising  from  the  inner  side  of  a 

VEIN<  venous  arch  on  the  dorsum  of  the  foot,  unite  into 

a  single  trunk,  which  ascends  in  front  of  the  inner  ankle,  along  the 
inner  side  of  the  leg,  behind  the  knee,  along  the  inner  and  front 
part  of  the  thigh,  where  it  passes  through  an  opening — the  saphe- 
nous opening — in  the  fascia  lata,  to  join  the  femoral  vein,  imme- 
diately below  the  crural  arch  (fig.  143).  In  this  long  course  it 
receives  many  tributary  veins,  some  of  which  are  often  large, 
especially  one  which,  coursing  round  the  inner  part  of  the  thigh, 
is  frequently  as  large  as  the  main  trunk.  Just  before  its 
termination  it  is  joined  by  the  superficial  veins,  which  accompany 
the  arteries  of  the  groin,  already  alluded  to,  p.  611.  Like  all 

J  Mr.  Listen  had  occasion  to  tie  the  external  iliac  artery  for  a  supposed  injury 
(by  a  pistol-ball)  to  the  femoral.  It  was  discovered,  after  the  death  of  the  patient, 
that  the  ball  had  injured  only  one  of  the  superficial  branches  of  the  femoral  about 
an  inch  from  its  origin.  See  his  paper  in  the  Med.  Chir.  Trans,  vol.  xxix.,  1846. 


614  CUTANEOUS  NERVES  OF  THE  THIGH. 

subcutaneous  veins,  it  is  provided  with  valves,  chiefly  where  joined 
by  other  veins,  to  support  the  column  of  the  blood. 

CUTANEOUS  The  distribution  of  the  cutaneous  nerves  of  the 

NEKVES.  thigh   varies    considerably,    but  they  are  always 

found  more  abundantly  on  the  inner  than  on  the  outer  aspect 
of  the  thigh.  The  nerves  are  divided  into  external,  middle,  and 
internal.  All  directly  or  indirectly  proceed  from  the  lumbar 
plexus,  and,  perforating  the  fascia  lata,  divide  in  the  subcutaneous 
tissue. 

a.  The  external  cutaneous  nerve  is  a  branch  of  the  second  and 
third  lumbar  nerves.     It  enters  the  thigh  beneath  Poupart's  liga- 
ment close  to  the  anterior  superior  spine  of  the  ilium.     Here  it 
divides  into  two  branches,  an  anterior  and  a  posterior.    The  anterior 
branch  comes   through  the  fascia  lata  about  four  inches   below 
Poupart's  ligament,  and  can  be  traced  down  the  outer  side  of  the 
thigh   as  far  as  the   knee,   giving  off  numerous  branches.      The 
posterior  branch,  after  coming  through  the  fascia  lata,  divides  into 
filaments,  which  are  distributed  to  the  skin  over  the  nates  and  the 
posterior  part  of  the  thigh. 

b.  The  middle  cutaneous  nerves,  one  or  two  in  number,  are  given 
off  by  the  anterior  crural  in  the  thigh.     They  pass  through  the 
sartorius  about  four  inches  below  Poupart's  ligament,  perforate  the 
fascia  lata,  and  descend  along  the  front  and  inner  part  of  the  thigh 
as  far  as  the  knee,  distributing  branches  on  either  side  ;  some  of 
which  communicate  with  the  long  saphenous  nerve.     In  its  course 
along  the  front  of  the  thigh  it  joins  with  the  crural  branch  of  the 
genito-crural  and  the  internal  cutaneous  nerves. 

c.  The  internal  cutaneous  nerve,  also  a  branch  of  the  anterior 
crural,  crosses  obliquely  over  the  sheath  of  the  femoral  artery.     It 
then  divides  into  two  branches,  an  anterior  and  an  internal ;  the 
anterior  branch  comes  through  the  fascia  lata  in  the  lower  third  of 
the  thigh,  where  it  terminates  in  two  branches,  one  being  distri- 
buted to  the  inner  side  of  the  knee,  the  other  crossing  over  the 
patella  to  the  outer  side  of  the  joint ;  the  internal  branch  perforates 
the  fascia  lata  just  above  the  knee-joint,  after  running  down  along 
the  posterior  border  of  the  sartorius,  and  supplies  the  integument 
on  the  inner  side  of  the  leg.     Whilst  still  beneath  the  fascia  lata, 


FASCIA   LATA.  615 

the  internal  cutaneous  nerve  unites  below  the  adductor  longus  in  a 
plexiform  manner  with  the  long  saphenous  and  obturator  nerves.1 

d.  The  crural  branch  of  the  genito-crural  nerve  perforates  the 
anterior  layer  of  the  sheath  of  the  femoral  vessels,  comes  through 
the  fascia  lata  immediately  below  Poupart's  ligament,  and  supplies 
the  skin  in  front  of  the  thigh.     About  two  or  three  inches  below 
the  crural  arch  it  usually  communicates  with  the  middle  cutaneous 
nerve.     It  also  distributes  a  few  filaments  to  the  femoral  artery  in 
its  passage  under  the  crural  arch. 

e.  The  inguinal  branch  of  the  ilio-inguinal  nerve,  after  emerging 
from  the  external  abdominal  ring,  supplies  the  skin  on  the  inner 
aspect  of  the  upper  third  of  the  thigh. 

Remove  the  subcutaneous  fat  and  the  deeper 
layer  of  the  superficial  fascia,  to  examine  the  dense 
white  fascia — the  fascia  lata — of  the  thigh.  The  use  of  this  fascia 
is  to  cover  the  muscles  of  the  thigh  collectively,  and  to  form 
separate  sheaths  for  each ;  so  that  it  not  only  keeps  them  together, 
but  maintains  each  in  its  proper  position.  A  knowledge  of  these 
sheaths  is  important,  because  they  interfere  with  the  progress  of 
deep-seated  matter  towards  the  surface,  and  cause  it  to  burrow  in 
this  or  that  direction  according  to  the  part  in  which  it  forms. 

The  fascia  is  not  of  equal  strength  all  round  the  thigh.  It  is 
comparatively  thin  on  the  inner  side ;  exceedingly  thick  and  strong 
down  the  outer  side  ;  here,  indeed,  it  has  the  appearance  of  a  dense 
expanded  aponeurosis,  strapping  down  the  vastus  externus  muscle, 
and  is  sometimes  called  the  ilio-tibial  band ;  and  it  certainly  per- 
forms the  office  of  a  tendon,  for  it  gives  insertion  between  its  two 
layers  to  two  powerful  muscles — namely,  the  tensor  fasciae  femoris, 
and  the  gluteus  maximus  (fig.  144). 

The  fascia  lata  is  attached  to  the  margin  of  the  bones  which 
constitute  the  framework  of  the  lower  extremity.  Beginning  from 
above,  its  attachment  can  be  traced  from  the  posterior  surface  of 
the  sacrum  and  coccyx,  along  the  crest  of  the  ilium,  thence  along 

1  It  is  important  to  note  that  one,  sometimes  two,  of  these  branches  of  the 
internal  cutaneous  crosses  the  sheath  of  the  femoral  artery,  just  where  the  sartorius 
begins  to  overlap  it,  and  therefore  at  the  spot  where  it  is  usually  tied.  See 
diagram,  p.  628. 


616 


FASCIA    LATA. 


FIG.  144. 


Poupart's  ligament  to  the  body  of  the  os  pubis  and  the  linea  ilio- 
pectinea,  and  along  the  rami  of  the  os  pubis  and  ischium.  Pro- 
ceeding down  the  thigh,  it  penetrates  on  each  side  of  the  limb  to 
the  linea  aspera,  forming  what  are  called  the  external  and  internal 
intermuscular  septa  ;  the  external  one,  the  stronger,  separates  the 
vastus  externus  anteriorly  from  the  short  head  of 
the  biceps,  both  of  which  have  origin  from  the 
fascia ;  the  internal  one  separates  the  vastus  in- 
ternus  in  front  from  the  adductor  muscles  behind. 
Below,  it  can  be  traced  round  the  knee-joint,  and 
is  particularly  strong,  especially  on  the  outer  side, 
where  it  is  attached  to  the  head  of  the  tibia  and 
fibula,  and  forms  the  insertion  of  the  tensor  fascias 
femoris.  The  fascia  lata  is  very  strong  over  the 
gluteus  medius — the  gluteal  aponeiirosis,  and  at 
the  upper  border  of  the  gluteus  maximus  divides 
into  two  layers,  one  superficial  to  the  muscle,  the 
other  deep  which  separates  this  muscle  from  the 
deeper  muscles,  and  becomes  connected  with  the 
great  sacro-sciatic  ligament.  The  fascia  lata  also 
furnishes  thinner  sheaths  for  the  separate  muscles. 
There  are  numerous  small  apertures  in  the 
fascia,  through  which  the  cutaneous  nerves  and 
vessels  are  transmitted  •  but  the  most  important 
one  is  the  large  opening — the  saphenous  opening 
— through  which  the  saphena  vein  passes  to  join 
the  femoral.  The  part  of  the  fascia  situated  ex- 
FASCIA  ON  THE  OUT-  ternal  to  the  saphenous  opening  is  termed  the 
SIDE  OF  THE  THIGH,  iliac  portion  of  the  fascia  lata ;  that  internal  to  it, 


1.  Tensor  fascise  femoris.    the  pubic  portion. 

2.  Gluteus  maximus. 

3.  Lower  fibres  of  ditto. 

4.  Fascia  lata. 


The  iliac  portion  is  attached  to  the  crest  of  the 
ilium,  to  the  whole  length  of  Poupart's  ligament, 
and,  in  conjunction  with  Gimbernat's  ligament,  to  the  linea  ilio- 
pectinea ;  from  this  attachment  it  arches  downwards  and  outwards, 
its  inner  margin  forming  the  outer  falciform  edge  of  the  saphenous 
opening ;  this  border  passes  over  the  anterior  sheath  (formed  by 
the  transversalis  fascia)  of  the  femoral  artery,  and  is  seen  to  be 


SAPHENOUS   OPENING. 


617 


continuous  below  with  the  pubic  portion,  which  can  be  traced  up- 
wards over  the  pectineus  and  adductor  longus  muscles,  behind  the 
posterior  sheath  (formed  by  the  iliac  fascia)  of  the  femoral  vessels, 
where  it  is  connected  with  the  sheath  of  the  iliacus  and  psoas 
muscles  and  the  fibrous  structures  of  the  hip-joint.  Above,  it  is 
attached  to  the  linea  ilio-pectinea,  to  the  body  and  the  ramus  of 
the  os  pubis. 

SAPHENOUS  r-^ne  saphenous  opening  is  an  oval  aperture  in  the 

OPENING  IN  THE  fascia  lata,  immediately  below  the  crural  arch,  on 
FASCIA  LATA.  foe  jnner  &{^e  of  the  front  of  the  thigh,  through 

which  the  saphena  vein  passes  to  join  the  femoral.     There  is  no 

FIG.  145. 


1.  Crural  arch. 

2.  Saphenous  opening  of 

the  fascia  lata. 

3.  Saphena  vein. 

4.  Femoral  vein. 


5.  Gimbernat's  ligament. 

6.  External      abdominal 

ring. 

7.  Position     of    the    in- 

ternal ring  in  dotted 
outline. 


DIAGBAM   OF   THE    FEMOKAL   RING   AND   THE    SAPHENOUS   OPENING. 
(The  arrow  is  introduced  into  the  femoral  ring.) 

definite  border  to  the  saphenous  opening  until  the  fascia — cribriform, 
which  covers  the  opening  and  blends  with  its  margin — has  been 
removed.  It  is  situated  just  below  the  crural  arch  and  external  to 
the  spine  of  the  os  pubis  ;  it  is  oval,  with  the  long  axis  vertical, 
and  is  about  one  inch  and  a  half  long  and  an  inch  broad.  Its  border 
on  the  inner  side  is  not  defined ;  for  here  the  fascia  lata  ascends 
under  the  femoral  vessels,  and  is  continuous  with  the  iliac  fascia  of 
the  pelvis.1  But  the  outer  or  iliac  border  is  clearly  defined.  This 


1  On  the  inner  side  of  the  femoral  vessels  the  pubic  portion  of  the  fascia  is 
attached  to  the  linea  ilio-pectinea. 


618  CRIBRIFORM   FASCIA. 

lies  in  front  of  the  femoral  vessels,  is  crescent-shaped,  with  the 
concave  upper  end  towards  the  os  pubis,  and  is  called  the  falciform 
process,  whilst  its  deeper  fibres  are  known  as  Burns'  ligament.  The 
lower  horn  of  the  crescent  curves  under  the  saphena  vein  with  a 
well-defined  border,  and  on  being  traced  upwards  becomes  less  well 
marked  until  it  is  gradually  lost  in  the  fascia  on  the  inner  side  of 
the  opening.  The  upper  horn,  Hey's  ligament,1  arches  over  the 
femoral  vein,  and  then  descending  slightly  is  continued  unin- 
terruptedly into  Gimbernat's  ligament — i.e.  into  that  part  of  the 
crural  arch  which  is  inserted  into  the  linea  ilio-pectinea.  The 
upper  horn  deserves  especial  attention,  because  it  forms  the  upper 
boundary  of  the  aperture  through  which  a  femoral  hernia  takes 
place;  and,  being  chiefly  concerned  in  the  constriction  of  the 
rupture,  must  be  divided  for  its  relief.  This  may  be  easily  ascer- 
tained by  introducing  the  little  finger  under  the  crural  arch,  on  the 
inner  side  of  the  femoral  vein — in  other  words,  into  the  femoral 
ring  (see  the  arrow  in  the  diagram).  Feel  how  the  upper  horn  of 
the  crescent  would  gird  the  neck  of  a  hernia,  and  that  its  tension 
is  greatly  influenced  by  the  position  of  the  limb ;  for  if  the  thigh 
be  bent  and  brought  over  to  the  other  side,  the  tension  of  all  the 
parts  is  materially  lessened.2 

CKIBBIFOKM  The  cribriform  fascia  is  so  called  because  it  is 

FASCIA.  perforated  with  numerous  apertures  for  the  passage 

of  the  superficial  vessels  and  lymphatics.  It  is  a  thin  membranous 
covering  over  the  saphenous  opening,  and  is  prolonged  from  the 
outer  edge  of  the  opening  over  the  sheath  of  the  femoral  vessels, 
and  adheres  on  the  inner  side  to  the  fascia  lata,  over  the  pectineus 
muscle.  Some  anatomists  describe  this  fascia  as  a  portion  of  the 
deeper  layer  of  the  superficial  fascia  ;  others  consider  it  as  a  thin 
prolongation  of  the  fascia  lata  itself  across  the  opening.  Its  chief 

1  This  upper  horn  is  sometimes  called  Hey's  ligament,  after  the  surgeon  who 
first  drew  attention  to  it.    (Observations  in  Surgery,  by  W.  Hey,  F.E.S.  London, 
1810.) 

2  We  must  .always  bear  in  mind  that,  though  the  crural  arch  and  the  fascia 
attached  to  it  have  received  particular  names,  they  are  not,  on  that  account,  distinct 
and  separate ;  but  all  are  intimately  connected,  and  portions  merely  of  one  con- 
tinuous expansion.     Thus  all  the  parts  are  kept  in  a  condition  of  mutual  tension, 
which  depends  very  much  on  the  position  of  the  thigh. 


PARTS   CONCERNED   IN   FEMORAL   HERNIA.  619 

surgical  importance  is  derived  from  the  fact  that  it  forms  one  of 
the  coverings  of  a  femoral  hernia. 

The  cribriform  fascia  must  now  be  removed  on  one  side  so  as  to 
display  the  saphenous  opening,  which  will  appear  as  represented 
in  fig.  145. 

ANATOMY  OF   THE   PARTS   CONCEENED   IN   FEMORAL   HERNIA. 

The  anatomy  of  the  parts  concerned  in  femoral  hernia  cannot 
be  thoroughly  understood  without  the  assistance  of  special  dissec- 
tions. The  following  demonstration  therefore  takes  for  granted 
that  the  student  has  the  opportunity  of  seeing  the  parts,  not  only 
on  their  femoral,  but  also  on  their  abdominal  side. 

The  different  parts  of  the  subject  should  be  examined  in  the 
following  order : — 

a.  The  formation  of  the  crural  arch. 

b.  The  arrangement  of  the  parts  as  they  pass  under  the  arch. 

c.  The  sheath  of  the  femoral  vessels. 

d.  The  crural  canal  and  ring. 

e.  The  practical  application  of  the  subject. 

POUPAKT'S  ^ne  lower  border  of  the  aponeurosis  of  the 

LIGAMENT  OR  external  oblique  muscle  extends  from  the  anterior 

CRURAL  ARCH.  superior  spine  of  the  ilium  to  .the  spine  of  the  os 

pubis,  and  forms  over  the  bony  excavation  beneath  the  crural  arch 
or  Pouparfs  ligament.  (It  is  marked  by  the  dark  line  in  fig.  145.) 
The  direction  of  the  arch  is  at  first  somewhat  oblique,  but  towards 
its  inner  half  becomes  nearly  horizontal.  In  consequence  of  its 
intimate  connection  with  the  fascia  lata  of  the  thigh,  the  line  of 
the  arch  describes  a  gentle  curve  with  the  convexity  downwards. 
The  arch  is  attached  to  the  spine  of  the  os  pubis,  and  also  for  some 
distance  along  the  linea  ilio-pectinea  (fig.  145).  This  additional 
attachment,  called  Gimbernafs  ligament^  is  of  importance,  for  it  is 
frequently  the  seat  of  stricture  in  femoral  hernia. 

GIMBERNAT'S  The  best  view  of  Gimbernat's  ligament  is  ob- 

LIGAMENT.  tained  from  within  the  abdomen  ;  it  being  only 

1  Don  Antonio  de  Gimbernat  was  a  Spanish  surgeon,  who  published,  in  1793, 
A  New  Method  of  Operating  for  the  Femoral  Hernia.     Madrid. 


620  PARTS   CONCERNED   IN   FEMORAL   HERNIA. 

necessary  to  remove  the  peritoneum.  It  is  that  portion  of  the 
aponeurosis  of  the  external  oblique  muscle  which  is  inserted  into 
the  linea  ilio-pectinea  for  about  an  inch  in  length.  It  is  placed 
nearly  horizontally  in  the  erect  posture,  and  is  triangular  with  its 
apex  at  the  os  pubis  and  its  base  directed  outwards.  In  front,  it 
is  continuous  with  the  crural  arch  ;  behind,  it  is  inserted  into  the 
linea  ilio-pectinea ;  externally,  it  is  continuous  with  the  fascia 
lata  through  Hey's  ligament  (fig.  145).  Its  length  is  from  three- 
quarters  of  an  inch  to  one  inch ;  but  it  is  usually  longer  in  the 
male  than  in  the  female. 

On  putting  your  finger  into  the  femoral  ring,  you  feel  the 
sharp  and  wiry  edge  of  this  ligament :  observe,  too,  that  as  the 
body  lies  on  the  table,  the  plane  of  the  ligament  is  perpendicular, 
and  therefore  that  it  recedes  from  the  surface. 

An  incision  should  now  be  made  through  the  fascia  lata  along 
the  entire  length  of  Poupart's  ligament ;  another  also  through  the 
fascia  vertically,  from  the  anterior  superior  iliac  spine  down  the 
thigh  for  about  four  inches ;  and  the  fascia  lata  carefully  dissected 
downwards  and  inwards  from  the  subjacent  structures.  This  will 
expose  the  structures  as  they  pass  under  Poupart's  ligament  in 
their  course  down  the  thigh. 

ARRANGEMENT  ^^e  crura^  arcn  transmits  from  the  abdomen  into 

OF  THE  PARTS  the  thigh  (proceeding  in  order  from  the  outer  side) 

WHICH  PASS  UNDER  the  following  objects  shown  in  fig.  146  :  1.  The 
THE  ARCH.  external  cutaneous  nerve.  2.  The  iliacus  with  the 

anterior  crural  nerve  lying  on  it  near  its  inner  border.  3.  The 
femoral  artery  resting  on  the  psoas  muscle.  4.  The  crural  branch 
of  the  genito-crural  nerve.  5.  The  femoral  vein.  6.  The  crural 
sheath  surrounding  the  femoral  vessels,  formed  in  front  by  the  fascia 
transversalis,  behind  by  the  fascia  iliaca.  7.«The  lymphatics  passing 
upwards  through  the  femoral  canal.  8.  The  pectineus.  These 
muscles  and  vessels  fill  up  the  space  beneath  the  crural  arch,  except 
on  the  inner  side  of  the  femoral  vein,  where  a  space  is  left  for  the 
passage  of  the  lymphatics  :  this  is  called  the  crural  or  femoral  ring. 
The  muscles  are  separated  from  the  vessels  by  a  strong  vertical 
fibrous  partition  passing  from  the  arch  to  the  bone,  which  is  nothing 
more  than  a  continuation  of  the  sheath  of  the  psoas.  The  artery,  too, 


PARTS   CONCERNED    IN   FEMORAL   HERNIA. 


621 


is  separated  from  the  vein  by  a  similar,  although  a  much  weaker 
partition,  and  there  is  a  third  close  to  the  inner  side  of  the  vein. 
These  three  partitions  not  only  keep  all  the  parts  in  their  right 
place,  but  confine  the  arch  down  to  the  bone,  and  prevent  its  being 
uplifted  by  any  protrusion  between  it  and  the  muscles  and  vessels. 
This,  coupled  with  the  close  attachment  of  the  fascia  iliaca  to  the 
crural  arch,  explains  why  a  femoral  hernia  rarely  takes  place  in 
any  other  situation  than  on  the  inner  side  of  the  femoral  vein.1 


.  146. 


External  cutaneous  n. 


Iliacus 

Anterior  crural  n.  .    .     . 
Psons.    ,  ... 


Crural  arch. 
External  ring. 

Femoral  ring. 

Femoral  vein  and  artery. 


POSITION  OF   PAETS    UNDER    THE    CKUEAL   AECH    (VERTICAL    SECTION). 

SHEATH  OF  THE  The  femoral  vessels  descend  beneath  the  crural 
FEMORAL  VESSELS,  arch,  enclosed  in  a  funnel-shaped  membranous 
sheath.  This  sheath  appears  to  be  derived  immediately  from  the 
arch  itself,  but  it  is  really  formed  in  front  by  a  prolongation  from 
the  fascia  transversalis  of  the  abdomen.  This  prolongation,  uniting 
with  the  continuation  from  the  fascia  iliaca  (to  join  the  fascia  lata) 
behind  the  femoral  vessels,  forms  a  funnel,  with  the  wide  part 

1  If  the  partitions  from  any  cause  yield,  or  become  slack,  then  a  rupture  may 
descend  in  front  of  the  vessels,  or  even  (though  this  is  rare)  on  the  outer  side  of 
the  artery. 


622 


PARTS   CONCERNED   IN   FEMORAL  HERNIA. 


uppermost,    into   which   the   femoral  vessels    enter.     This  is  the 
funnel-shaped  sheath  of  the  femoral  vessels. 

The  fascia  transversalis,  descending  over  the  femoral  vessels, 
forms  the  front  part  of  their  sheath  ;  the  hind  part  of  the  sheath  is 
formed  by  the  fascia  iliaca,  which  runs  down  behind  the  vessels  to 
join  the  pubic  portion  of  the  fascia  lata.  The  sheath  descends  as 
low  as  the  lower  horn  of  the  saphenous  opening,  where  it  is  gradu- 
ally lost  upon  the  external  cellular  coat  (tunica  adventitia)  of  the 
femoral  vessels.  The  outer  part  of  the  sheath,  in  front,  is  perforated 

FIG.  147. 


1, 1.  Fascia  transver- 
salis. 

2.  Internal  ring. 

3.  Crural     arch     re- 

flected. 


4.  Sheath  of  the  fe- 

moral vessels. 

5.  Saphena  vein. 


DIAGRAM    OF    THE    SHEATH    OF    THE    FEMORAL    VESSELS. 

by  the  crural  branch  of  the  genito-crural  nerve,  and  the  superficial 
arteries  of  the  groin  ;  the  inner  part,  by  the  saphena  vein  and 
some  lymphatic  vessels. 

The  sheath  of  the  femoral  vessels  is  divided  into  three  com- 
partments separated  from  each  other  by  partitions :  the  outer  is 
occupied  by  the  femoral  artery;  the  middle,  by  the  femoral 
vein ;  the  inner  is  the  crural  canal,  into  which  a  femoral  hernia 
descends. 

The  deep  crural  arch  is  the  thickened  band  of  fibres  connected 
with  the  front  of  the  crural  sheath;  the  fibres  run  in  the  same 


PARTS   CONCERNED   IN   FEMORAL   HERNIA.  623 

direction  as  the  crural  arch,  but  quite  independently  of  it,  as 
shown  in  fig.  147;  these  bands  He  over  the  neck  of  the  sac  of  a 
femoral  hernia,  and  are  often  the  seat  of  the  stricture. 

Practically,  the  sheath  is  important  for  many  reasons : — 
1.  A  femoral  hernia  descends  within  it.  2.  It  constitutes, 
therefore,  one  of  the  coverings,  fascia  propria,  of  the  hernia.  3. 
It  contains  within  its  substance  the  deep  crural  arch,  which  not 
infrequently  forms  the  stricture  of  a  femoral  hernia,  and  has, 
therefore,  to  be  divided  before  the  intestine  can  be  returned. 

CKURAL  CANAL  The  hollow  under  the  crural  arch  is  completely 

AND  FEMORAL  occupied  by  the.  structures  before  mentioned,  ex- 

RlNQ-  cept   for   a    small  triangular   space,  forming  the 

inner  compartment  of  the  femoral  sheath,  called  the  crural  canal. 
The  canal  is  on  the  inner  side  of  the  femoral  vein,  and  is  from  a 
quarter  to  half  an  inch  in  length.  Its  base  commences  above  in 
the  femoral  ring,  and  its  apex  ends  below  at  the  saphenous  opening. 
In  front,  it  has  Poupart's  ligament  and  the  falciform  process  of  the 
iliac  portion  of  the  fascia  lata,  and  is  formed  by  the  fascia  trans- 
versalis  ;  behind,  it  is  formed  by  the  fascia  iliaca  ;  internally,  it  is 
formed  by  the  junction  of  the  fascia  transversalis  and  the  fascia 
iliaca,  and  is  in  relation  with  the  base  of  Gimbernat's  ligament; 
externally,  it  is  separated  from  the  femoral  vein  by  the  septum  of 
fascia  which  divides  the  middle  from  the  inner  compartment  of 
the  crural  sheath. 

The  femoral  ring  is  the  upper  opening  of  the  crural  canal,  and 
is  bounded,  in  front,  by  the  superficial  and  deep  crural  arches  ; 
behind,  by  the  horizontal  ramus  of  the  os  pubis,  the  pectineus,  and 
the  pubic  portion  of  the  fascia  lata ;  on  the  outer  side,  by  the 
fascial  septum  separating  it  from  the  vein ;  on  the  inner  side,  by 
the  thin,  wiry  edge  of  Gimbernat's  ligament,  the  conjoined  tendon 
of  the  internal  oblique  and  transversalis,  the  fascia  transversalis, 
and  the  fibres  of  the  deep  crural  arch.  In  the  undisturbed  con- 
dition of  the  parts  there  is  no  gap ;  it  is  only  a  weak  place,  which, 
when  a  hernia  escapes  through  it,  feels  like  a  ring :  hence  the 
name  of  femoral  ring.1 

1  The  femoral  ring  is  naturally  occupied  by  a  little  fat  and  cellular  membrane, 
by  lymphatic  vessels,  and  often  by  a  small  lymphatic  gland.  But  we  have  never 


624  PARTS   CONCERNED   IN   FEMORAL    HERNIA. 

The  femoral  ring  is  surrounded  on  all  sides  by  unyielding 
structures.  This  accounts  for  the  little  benefit  afforded  by  the 
warm  bath  in  cases  of  strangulation.  Sir  W.  Lawrence  was  in 
the  habit  of  saying  that  he  never  saw  a  strangulated  femoral 
hernia  where  the  warm  bath  was  of  any  avail. 

PRACTICAL  From  what  has  been  said,  the  student  ought 

APPLICATTON  OF  now  to  understand — 1,  at  what  aperture  a  femoral 
THE  SUBJECT.  hernia  escapes  from  the  abdomen  ;  2,  the  course 

which  it  takes,  and  its  relations  to  the  surrounding  parts  ;  3,  the 
proper  mode  of  attempting  the  reduction ;  4,  the  structure  and 
arrangement  of  its  coverings ;  and,  5,  the  probable  seat  of  stricture. 

The  hernia  escapes  from  the  abdomen  through  the  femoral  ring 
— that  is,  under  the  weak  part  of  the  crural  arch,  between  the 
femoral  vein  and  Gimbernat's  ligament.  Here  is  the  mouth  of 
the  hernial  sac,  or  that  part  of  it  which  communicates  with  the 
abdomen.  It  descends  for  a  short  distance  nearly  perpendicu- 
larly, and  projects  as  a  small  tumour  in  front  of  the  pectineus 
muscle.  Its  progress  downwards,  however,  is  soon  arrested,  partly 
by  the  very  close  adhesion  of  the  subcutaneous  structures  to  the 
lower  margin  of  the  saphenous  opening ;  partly  by  the  flexion  of 
the  thigh.  Consequently,  if  the  hernia  increases  in  size,  it  usually 
rises  over  the  crural  arch,  where  the  subcutaneous  tissue  offers  less 
resistance  ;  and  the  bulk  of  the  hernia  extends  outwards  towards 
the  ilium,  assuming  more  or  less  of  an  oblong  form,  with  the  long 
axis  parallel  to  the  crural  arch.  Since,  then,  the  body  of  the 
hernia  forms  a  very  acute  angle  with  the  neck,  the  right  mode  of 
attempting  its  reduction  is,  to  draw  it,  first,  down  from  the  groin, 
and  then  to  make  pressure  on  it,  backwards,  in  the  direction  of 
the  femoral  ring. 

COVERINGS  OF  The  coverings  of  a  femoral    hernia  are  as  fol- 

A  FEMORAL  lows  : — It  first  protrudes  before  it  the  peritoneum, 

HERNIA-  technically  called  the   hernial  sac.1     The    sac    is 

met  with  anything  deserving  the  name  of  a  diaphragm  or  membranous  septum, 
such  as  is  described  by  Cloquet  as  the  septum  crurale,  and  is,  surgically,  of  no 
importance. 

1  In  some  cases  the  fascia  propria  so  much  resembles  the  hernial  sac,  that  it  is 
not  easy  to  distinguish  between  them.  Generally  speaking,  they  are  separated  by 
a  small  quantity  of  fat. 


PARTS    CONCERNED    IN    FEMORAL    HERNIA. 


625 


covered  by  more  or  less  fat,  according  to  the  condition  of  the 
patient,  called  the  siibperitoneal  fat.  It  next  pushes  before  it  the 
sheath  of  the  femoral  vessels,  which  forms  an  investment  more  or 
less  thick.  In  front  of  this  is  the  cribriform  fascia.  Lastly,  there 
is  the  subcutaneous  tissue  and  skin. 

SEAT  OF  The  seat  of  stricture  is  usually  at  the  femoral 

STRICTURE.  ring,  and  the  position  of  the  neighbouring  blood- 

vessels indicates  that  the  proper  direction  in  which  to  divide  the 

FIG.  148. 


VIEW    OF    THE    DIFFERENT    DIRECTIONS    WHICH    AN    ABNORMAL    OBTURATOR    ARTERY 
MAY  TAKE.       (SEEN    FROM   ABOVE.) 

A.  1.  Q-imbernat's  ligament.  B.  1.  Gimbernat's  ligament. 

2.  Femoral  ring.  2.  Abnormal  obturator  artery. 

3.  Abnormal  obturator  artery.  3.  Femoral  ring. 

4.  External  iliac  vein.  4.  External  iliac  vein. 

5.  External  iliac  artery.  5.  External  iliac  artery. 

6.  Diminutive  obturator  artery  arising  6.  Diminutive  obturator  artery. 

from  its  normal  source. 

stricture  is,  either  directly  inwards,  through  Gimbernat's  ligament, 
as  recommended  by  Sir  W.  Lawrence,  or  upwards  through  Key's 
ligament,  as  recommended  by  Sir  A.  Cooper.1  There  is  no  risk  of 
wounding  an  artery,  supposing  the  vessels  to  take  their  ordinary 
course.  But  it  occasionally  happens  (fig.  148),  that  the  obturator 
artery  runs  above  (in  the  recumbent  position)  the  femoral  ring ;  in 
such  a  case,  the  neck  of  the  sac  would  be  encircled  by  a  large 

1  The  operation  recommended  by  Sir  A.  Cooper  is  that  usually  performed  now  ; 
because,  if  Gimbernat's  ligament  be  divided,  its  cut  edges  often  retract  to  such  an 
extent,  that  no  truss  can  possibly  retain  the  hernia  when  the  patient  assumes  the 
erect  posture. 

S  S 


626  SARTORIUS. 

Hood- vessel.1  From  the  examination  of  two  hundred  bodies,  the 
chances  are  about  seventy  to  one  against  this  unfavourable  dis- 
tribution. But  the  possibility  of  it  has  given  rise  to  this  rule  in 
practice — not  to  cut  deeply  in  any  one  place  through  the  stricture, 
but  rather  to  notch  it  in  several.  By  this  proceeding  we  are  much 
less  likely  to  wound  the  abnormal  artery,  because  it  does  not  run 
at  the  base  of  Gimbernat's  ligament,  but  about  a  line  and  a  half 
from  the  margin  of  it.2 

Such  is  an  outline  of  the  anatomy  of  the  parts  concerned  in  a 
femoral  hernia.  The  normal  anatomy  in  each  case  being  similar, 
it  might  be  supposed  that  all  operations  for  the  relief  of  this  kind 
of  hernia  would  be  straightforward  and  pretty  much  alike ;  but 
this  is  very  far  from  being  the  case :  indeed,  surgeons  agree 
that  they  never  operate  without  the  expectation  of  meeting  some 
peculiarity. 

The  fascia  must  now  be  removed  from  the  front 
of  the  thigh,  without  disturbing  the  subjacent 
muscles  from  their  relative  positions.  The  mass  of  muscles,  on 
the  inner  side  of  the  thigh,  consists  of  the  adductors ;  that  in  the 
middle,  of  the  extensors  :  the  long  thin  muscle  crossing  obliquely 
in  froi:  •  from  the  outer  to  the  inner  side  is  the  sartorius.  In  the 
middle  are  seen  the  femoral  vessels,  and  the  anterior  crural  nerve 
emerging  beneath  the  crural  arch. 

This,  a  narrow,  flat  muscle  (fig.  149,  i),  arises 

SABTOBIUS.  ,,          ,,  •  •  r  ,,      .,.  -. 

from  the  anterior  superior  spine  of  the  ilium,  and 

from  the  ridge  below  to  the  extent  of  an  inch.  It  passes  obliquely 
like  a  strap  over  the  front  of  the  thigh  towards  the  inner  side  ;  and 
then  descends  almost  perpendicularly  on  the  inner  side  of  the  thigh  as 
far  as  the  knee,  where  it  terminates  in  a  flat  tendon  which  expands, 

1  The  museum  of  St.  Bartholomew's  Hospital  contains  two  examples  of  double 
femoral  hernias  in  the  male,  with  the  obturator  arising  on  each  side  from  the 
epigastric.  In  three  out  of  four  herniae  the  obturator  runs  on  the  inner  side  of  the 
mouth  of  the  sac. 

*  During  the  session  of  1867-68  more  than  half  a  dozen  instances  occurred 
where  the  obturator  artery  was  given  off  by  a  common  origin  with  the  epigastric 
artery.  In  all  these  cases,  however,  the  artery  passed  close  by  the  bone,  that  is, 
behind  the  sac,  so  that  it  would  not  have  been  injured  in  the  operation  for  the 
relief  of  strangulation. 


SCARPA'S  TRIANGLE.  627 

and  is  inserted  into  the  inner  and  front  part  of  the  tibia  just  below 
its  tubercle.  The  tendon  appears  all  the  wider  on  account  of  its 
broad  connection  with  the  fascia  of  the  leg,  which  extends  as  low 
as  the  internal  malleolus.  The  broad  insertion  of  this  muscle  lies 
•anterior. to  and  covers  the  tendinous  insertions  of  the  gracilis  and 
semi-tendinosus,  and  between  them  is  a  bursa.  A  large  bursa l  is 
interposed  between  the  tendon  and  the  internal  lateral  ligament. 
The  chief  action  of  the  muscle  is  to  fix  the  pelvis  steadily  on  the 
thigh.2  It  first  bends  the  leg  upon  the  thigh,  and  then  bends  the 
thigh  upon  the  abdomen.  It  crosses  one  leg  over  the  other,  as 
tailors  sit  when  at  work.  If  the  leg  be  the  fixed  point,  it  will 
bend  the  trunk  upon  the  thigh  and  rotate  the  pelvis  inwards. 
Its  nerve  conies  from  the  middle  cutaneous  branch  of  the  anterior 
•crural. 

SCARPA'S  In  consequence  of  the  oblique  direction  of  the 

TRIANGLE.  upper  third  of  the  sartorius,  a  triangle  is  formed, 

which  has  this  muscle  and  the  adductor  longus  for  its  two  sides, 
•and  the  crural  arch  for  its  base  :  the  triangle  is  called  Scarpa's.3 

Its  floor  is  formed  by  the  iliacus,  the  psoas,  the  pectineus,  and  the 
adductor  longus,  with  sometimes  the  adductor  brevis  between  the 
borders  of  the  two  latter  muscles.  The  contents  of  this  important 
space  should  be  carefully  displayed,  and  their  relative  positions 
well  studied.  This  triangle  contains  all  the  parts  which  pass  under 
the  crural  arch :  namely,  from  without  inwards,  the  external  cuta- 
neous nerve,  close  to  the  anterior  spine  of  the  ilium ;  the  iliacus 
and  psoas ;  the  anterior  crural  nerve  and  its  divisions,  especially 
the  long  saphenous  nerve  ;  the  crural  branch  of  the  genito-crural 
nerve,  the  common  femoral  artery  with  its  two  large  divisions,  the 
superficial  femoral  and  the  profunda,  which  run  down,  nearly 
parallel  to  each  other,  the  latter  being  the  more  external  and 
giving  off  the  internal  and  external  circumflex  arteries ;  the 

1  In  persons,  females  especially,  who  are  in  the  habit  of  riding,  this  bursa 
sometimes  becomes  enlarged. 

2  Hence  the  name  given  to  it  by  Spigelius  (De  Corporis  Hum.  Fabric.),  '  Quern 
•ego  sartorium  musculum  vocare  soleo,  quod  sartores  eo  maxim£  utuntur,  dum  crus 
cruri  inter  consuendum  imponunt.' 

8  So  called  in  compliment  to  the  Italian  anatomist  who  first  tied  the  femoral 
in  it  for  popliteal  aneurism. 

s  s  2 


628 


ADDUCTOR   MUSCLES. 


femoral  vein,  joined  by  the  proftmda  vein  and  the  internal 
saphena,  and  the  pectineus  muscle  with  the  deep  external  pudic 
artery. 

The  triangle  is  important  in  a  surgical  point  of  view,  since  it 
is  in  this  Space  that  the  femoral  artery  is   usually  ligatured  for 

FIG.  149. 


1.  Sartorius. 

2.  Adductor  longus. 

3.  External    cutaneous 

n. 

4.  Iliacus  internus. 

5.  Anterior  crural  n. 

6.  Femoral  arterv. 


7.  Femoral  vein. 

8.  Pectineus. 

9.  Long  saphenous  n. 

10.  Internal  cutaneous 

n. 

11.  Nerve  to  vastns  in- 

ternus. 

12.  Middle  cutaneous  n. 


DIAGRAM    OF    SCARPA's    TRIANGLE. 

popliteal  aneurism.  The  guide  to  the  artery  is  the  inner  border 
of  the  sartorius.  The  situation  at  which  this  muscle  crosses  over 
the  femoral  artery,  varies  from  one  and  a  half  to  four  and  a  half 
inches  below  Poupart's  ligament;  so  that  no  rule  can  be  laid  down 
as  to  the  exact  situation  where  the  artery  disappears  beneath  the 
sartorius.  The  best  way  to  find  the  inner  border  of  the  muscle 
during  life,  is  to  make  the  patient  put  it  in  action. 

ADDUCTOR  A.  strong  group  of  muscles,  called  the  adductors, 

MUSCLES.  extends  along  the  inner  side  of  the  thigh,  from 

the  pelvis  to  the  femur.  Their  two  most  important  actions  are 
to  co-operate  in  balancing  the  pelvis  steadily  on  the  thigh,  as  in 


ADDUCTOR   MUSCLES.  C29 

standing  on  one  leg ;  and  (if  the  fixed  point  be  reversed)  to  draw- 
together  or  adduct  the  thighs,  at  the  same  time  rotating  the  thigh 
externally.  They  are  five  in  number,  and  are  supplied,  with  one 
exception — the  pectineus — by  the  same  nerve,  namely,  the  obtu- 
rator. They  are  termed,  respectively,  the  gracilis,  adductor  longus, 
pectineus,  adductor  brevis,  and  adductor  magnus.  The  innermost 
is  the  gracilis ;  to  clean  it  properly,  it  should  be  stretched  by 
separating  one  thigh  from  the  other. 

This  long,  flat  muscle  arises  by  a  broad,  ribbon- 
like  tendon,  two  to  three  inches  in  breadth,  from 
the  os  pubis  close  to  the  symphysis,  and  from  the  inner  margin  of 
the  rami  of  the  os  pubis  and  ischium.  It  descends  almost  perpen- 
dicularly on  the  inner  side  of  the  thigh,  and  terminates  in  a  thin 
round  tendon  which  subsequently  spreads  out,  and  is  inserted  into 
the  inner  side  of  the  upper  part  of  the  tibia  below  the  tubercle, 
immediately  behind  the  sartorius  and  above  the  semi-tendinosus. 
The  tendon  plays  over  the  internal  lateral  ligament  of  the  knee- 
joint,  and  there  is  a  bursa  common  to  it  and  the  semi-tendinosus 
to  diminish  friction.  This  muscle  assists  in  fixing  the  pelvis,  and 
in  adducting  the  thigh  ;  it  further  helps  to  bend  the  knee.  Its 
nerve  comes  from  the  anterior  division  of  the  obturator. 

ADDUCTOR  This  triangular  muscle  lies  between  the  gracilis 

LONGUS.  and  the  pectineus,  and  arises  by  a  round  tendon 

from  the  front  of  the  body  of  the  os  pubis  below  the  crest.  As  it 
descends,  the  muscle  becomes  broader,  and  passing  downwards, 
outwards,  and  backwards,  is  inserted  by  a  broad  aponeurosis  into 
the  middle  third  of  the  inner  margin  of  the  linea  aspera  of  the 
femur.  It  forms  with  the  sartorius  the  triangular  space  called 
Scarpa's  triangle,  above  described.  It  rests  upon  the  adductor 
brevis  and  magnus,  the  profunda  vessels,  and  the  anterior  branches 
of  the  obturator  vessels  and  nerve.  It  is  supplied  by  the  anterior 
•division  of  the  obturator  nerve. 

This  muscle  lies  on  the  same  plane,  but  external 

to  the  adductor  longus,  from  which  it  is  separated 

by  a  slight  interval,  in  which  may  be  seen  the  adductor  brevis  and 

the  anterior  division  of  the  obturator  nerve.     It  arises  from  the 

liiiea  ilio-pectinea,  from  the  triangular  surface  of  the  os  pubis  in 


630    COURSE  AND  RELATIONS  OF  THE  FEMORAL  ARTERY. 

front  of  the  line,  and  from  the  fascial  prolongation  of  Gimbernat's 
ligament  covering  the  muscle;  it  passes  downwards,  outwards,  and 
backwards,  and  is  inserted  into  the  upper  part  of  the  ridge  leading 
from  the  lesser  trochanter  to  the  linea  aspera.  It  lies  upon  the 
capsular  ligament  of  the  hip-joint,  the  adductor  brevis,  the  ob- 
turator vessels  and  nerve,  and  the  obturator  externus.  Its  nerve 
comes  from  the  anterior  crural  which  runs  under  the  femoral 
vessels  to  enter  it  close  to  its  outer  border ;  sometimes  also  from 
the  obturator,  and  the  accessory  obturator  if  present  (p.  498). 

By  separating  the  contiguous  borders  of  the  pectineus  and  the 
adductor  longus,  the  adductor  brevis  is  exposed  with  the  anterior 
division  of  the  obturator  artery  and  nerve  lying  upon  it.  To 
obtain  a  complete  view  of  it,  the  pectineus  and  adductor  longus 
must  be  reflected  from  their  origins  and  turned  downwards.  The 
obturator  nerve  supplies  all  the  adductors.  It  leaves  the  pelvis 
through  the  upper  part  of  the  obturator  foramen,  and  soon  divides 
into  an  anterior  and  posterior  branch  :  the  anterior  runs  in  front 
of  the  adductor  brevis,  and  supplies  the  hip-joint,  the  adductor 
longus,  the  gracilis,  and  sometimes  the  adductor  brevis  and  the 
pectineus ;  the  posterior  runs  behind  the  adductor  brevis,  and 
supplies  it  as  well  as  the  obturator  externus,  the  adductor  magnus,, 
and  the  knee-joint. 

The  student  should  now,  before  the  parts  are  disturbed, 
examine  the  femoral  artery  as  it  passes  down  along  the  centre  of 
Scarpa's  triangle :  its  further  course  will  be  described  later  on,  as 
well  as  the  branches  which  come  off  from  it. 

COUBSE  AND  ^e  femoral  artery  is    a   continuation    of  the 

EELATIONS  or  external  iliac.     Passing  beneath  the  crural  arch 

THE  FEMORAL  at  a  point  midway  between  the  spine  of  the  ilium 

and  the  symphysis  pubis,  it  descends  along  the 
front  and  inner  side  of  the  thigh.  At  the  junction  of  the  upper 
two-thirds  with  the  lower  third  of  the  thigh,  it  passes  through  an 
opening  in  the  tendon  of  the  adductor  magnus,  and,  entering  the 
ham,  takes  the  name  of  popliteal.  A  line  drawn  from  the  point 
indicated  of  the  crural  arch  to  the  adductor  tubercle  on  the  internal 
condyle  corresponds  with  the  course  of  the  artery.  Its  distance  from 
the  surface  increases  as  it  descends.  Immediately  under,  and  for 


ADDUCTOR   MUSCLES.  631 

a  short  distance  below  the  crural  arch,  it  is  supported  by  the  inner 
border  of  the  psoas ;  lower  down  it  runs  in  front  of  the  pectineus, 
but  separated  from  it  by  the  profunda  vessels ;  still  lower  down,  it 
lies  upon  the  adductor  longus,  and  then  upon  the  adductor  magnus.. 

That  part  of  the  artery  which  extends  from  the  crural  arch  to- 
the  giving  off  of  the  profunda,  is  called  the  common  femoral  artery ; 
its  continuation  beyond  the  profunda  is  termed  the  superficial 
femoral ;  and  it  is  the  latter  vessel  which  is  ligatured  for  aneurism 
of  the  popliteal  artery. 

In  the  upper  third  of  the  thigh,  the  artery  is  situated  in  Scarpa's 
triangle,  and  is  comparatively  superficial,  having  in  front  the  skin, 
superficial  fascia  and  fat,  inguinal  glands,  deep  fascia,  the  fascia 
lata,  the  crural  branch  of  the  genito-crural  nerve,  and  the  sheath 
of  the  femoral  vessels.  About  the  middle  third  it  is  more  deeply 
seated,  and  is  covered  in  addition  by  the  sartorius ;  and  lower  down 
by  a  tendinous  aponeurosis,  which  stretches  from  the  adductor 
longus  and  magnus  over  to  the  vastus  internus.  This,  which  forms 
part  of  Hunter's  canal,  will  be  examined  presently. 

The  femoral  artery  in  Scarpa's  triangle  lies  upon  the  psoas,  the 
two  branches  of  the  anterior  crural  nerve  to  the  pectineus,  the  pro- 
funda vein,  and  the  pectineus  ;  to  its  outer  side  it  has  the  anterior 
crural  nerve  (separated  from  it  by  a  few  fibres  of  the  ilip-psoas)^ 
the  profunda  artery,  and  the  long  saphena  nerve ;  to  its  inner  side 
it  has  the  femoral  vein. 

ADDUCTOR  This  muscle  arises  from  the  front  surface  of  the 

BREVIS.  body  of  the  os  pubis  below  the  spine,  and  from  it& 

descending  ramus  for  about  an  inch,  between  the  gracilis  and  the 
obturator  externus  ;  it  widens  as  it  descends  outwards  and  back- 
wards, and  is  inserted  behind  the  pectineus  into  the  whole  length 
of  the  ridge  leading  from  the  lesser  trochanter  to  the  linea  aspera. 
Behind,  it  rests  upon  the  posterior  division  of  the  obturator  vessels 
and  nerve,  and  the  adductor  magnus.  Its  nerve  is  derived  from 
the  obturator.  By  reflecting  it  from  its  origin,  the  following 
muscle  is  exposed.1 

1  Beneath  the  adductor  brevis,  and  running  parallel  with  the  upper  border  of 
the  adductor  magnus,  is  seen  the  obturator  externus.  But  the  description  of  this 
muscle  is  deferred  till  the  dissection  of  the  external  rotators  of  the  thigh. 


632  ADDUCTOR   MUSCLES. 

ADDUCTOR  This  muscle  arises  from  the  lower  part  of  the 

MAGNUS.  descending   ramus  of  the  os  pubis  between  the 

adductor  brevis  and  obturator  externus,  from  the  margin  of  the 
ascending  ramus  of  the  ischium,  and  from  the  lower  and  anterior 
part  of  the  tuberosity  of  the  ischium.  Its  fibres  spread  out,  and 
are  inserted,  behind  the  other  adductors,  into  the  lower  part  of  the 
linea  quadrati,  into  the  ridge  leading  from  the  great  trochanter  to 
the  linea  aspera,  also  into  the  whole  length  of  the  linea  aspera,  and 
the  ridge  leading  from  it  to  the  inner  condyle  ;  while  those  fibres 
which  arise  from  the  tuberosity  of  the  ischium  pass  vertically  down- 
wards, and  are  inserted  by  a  rounded  tendon  into  the  adductor 
tubercle  on  the  inner  condyle  of  the  femur.  Between  the  muscular 
fibres  of  the  middle  and  lower  thirds  of  the  insertion  of  this  muscle, 
the  femoral  artery  passes  to  the  back  of  the  thigh.  The  upper 
fibres  pass  transversely  outwards  to  their  insertion,  while  the  lower 
fibres  descend  nearly  vertically.  In  front  of  the  muscle  are,  the 
adductor  longus  and  brevis,  the  vastus  internus,  the  obturator  nerve 
and  artery,  and  the  profunda  artery ;  above  it,  are  the  internal  cir- 
cumflex artery,  the  obturator  externus,  and  the  quadratus  femoris ; 
behind  it,  the  biceps,  semi-tendinosus  and  semi-membranosus, 
the  great  sciatic  nerve,  and  the  gluteus  maximus.  Its  nerve 
comes  from  the  posterior  division  of  the  obturator  and  the  great 
sciatic.  Observe  that  all  the  adductor  muscles  are  inserted  into 
the  femur  by  flat  tendons  more  or  less  connected. 

About  the  junction  of  the  upper  two-thirds  with  the  lower  third 
of  the  thigh,  the  femoral  artery  passes  through  an  oval  opening  in 
the  tendon  of  the  adductor  magnus. 

PSOAS  MAGNUS  These  muscles  have  been  fully  described  in  the 

AND  ILIACUS.  dissection  of  the  abdomen  (p.  488). 

TENSOR  FASCIA          This  muscle  is  situated  at  the  upper  and  outer 
FEMORIS.  par^  of  the  thigh.     It  arises  from   the   anterior 

part  of  the  external  lip  of  the  crest  of  the  ilium,  and  from  the 
surface  below  the  anterior  superior  spine.  It  descends  with  a 
slight  inclination  backwards,  and  is  inserted,  at  the  junction  of  the 
upper  with  the  middle  third  of  the  thigh,  between  two  layers  of 
the  strong  aponeurosis,  generally  described  as  part  of  the  fascia 
lata,  which  is  continued  downwards  to  the  head  of  the  tibia,  and  is 


EXTENSOR   MUSCLES.  633 

•called  the  ilio-tibial  band  (p,  616). l  Its  chief  use  is  to  fix  the  pelvis 
steadily  on  the  thigh,  and  to  rotate  the  thigh  inwards  ;  in  this  last 
.action  it  co-operates  with  the  anterior  fibres  of  the  gluteus  medius, 
with  which  it  is  almost  inseparably  connected.  Anyone  may  con- 
vince himself  of  this  by  placing  his  hand  on  the  hip,  and  rotating 
the  thigh  inwards.  Both  these  muscles  are  supplied  by  the  same 
nerve — the  superior  gluteal. 

To  form  an  adequate  idea  of  the  strength,  extent,  and  connec- 
tions of  the  aponeurosis  on  the  outer  side  of  the  thigh,  it  should  be 
separated  from  the  vastus  externus  muscle  upon  which  it  lies. 
There  is  no  difficulty  in  doing  so,  for  it  is  united  to  the  muscle  by 
an  abundance  of  loose  connective  tissue.2  With  a  little  persever- 
ance the  aponeurosis  can  be  traced  to  the  linea  aspera,  the  head  of 
the  tibia,  and  the  fibula,  completely  protecting  the  outer  side  of  the 
knee-joint. 

EXTENSOB  ^ie  Powerftd  fleshy  muscles  occupying  the  front 

MUSCLES  OB  of  the    thigh,   and    situated  between  the   tensor 

QUADBICEPS  fasciae  on  the  outer  side,  and  the  adductors  on  the 

XTENSOB.  inner,  are  the  extensors  of  the  leg.     One  of  them 

— the  rectus — arises  from  the  pelvis  ;  the  other — the  triceps — arises 
from  the  shaft  of  the  thigh-bone  by  three  portions,  called,  re- 
spectively, the  crttreus,  the  vastus  internus,  and  externus.  All  are 
.supplied  by  the  anterior  crural  nerve. 

To  see  the  origins  of  the  rectus  femoris,  dissect  between  the 
origin  of  the  sartorius  and  the  tensor  fascise ;  in  doing  so,  avoid 
injuring  the  branches  of  the  external  circumflex  artery. 

R,ECTUS  This  bipenniform  muscle  arises  from  the  pelvis 

FEMOBIS.  by  two  strong  tendons,  which  soon  unite  at  an 

acute  angle  :  one — the  straight  tendon — is  round,  and  arises  from 
the  anterior  inferior  spine  of  the  ilium ;  the  other — the  reflected 
tendon — is  flat,  and  comes  from  the  rough  surface  of  the  ilium,  just 
above  the  acetabulum.  The  muscle  descends  along  the  front  of  the 

1  The  deeper  of  these  two  layers  runs  up  to  be  strongly  connected  with  the 
tendon  of  the  rectus  and  the  front  of  the  capsule  of  the  hip-joint. 

2  When  this  tissue  becomes  the  seat  of  suppuration,  the  pus  is  apt  to  extend 
.all  down  the  outside  of  the  thigh,  not  being  able  to  make  its  way  to  the  surface  by 
reason  of  the  dense  fascia. 


634  EXTENSOR.   MUSCLES. 

thigh,  and  is  inserted  into  the  common  extensor  tendon,  which  will 
be  presently  examined.  The  structure  of  this  muscle  is  remark- 
able. A  tendon  runs  down  the  centre,  and  the  muscular  fibres  are 
inserted  on  either  side  of  it,  like  the  vane  on  the  shaft  of  a  feather. 
Notice  also  that  the  surface  of  the  upper  part  of  the  rectus  is 
apoiieurotic  in  front  and  muscular  behind,  while  the  reverse  is  seen 
at  the  lower  part  not  far  from  its  insertion.  Its  nerve  comes  from 
the  anterior  crural.1 

TRICEPS  Ex-  This  mass  of  muscle  invests  like  a  cloak   the 

TEXSOK.  greater  part  of  the  front  and  sides  of  the  shaft  of 

the  femur  ;  therefore,  the  whole  of  it  cannot  be  seen  without  com- 
pletely dissecting  the  thigh.  It  consists  of  an  outer,  middle,  and 
inner  portion,  called,  respectively,  the  vastus  externus,  the  crureus, 
and  the  vastus  internus. 

The  vastus  externus  arises  by  a  strong  glistening  aponeurosis 
from  the  outer  side  of  the  base  of  the  great  trochanter,  from  the 
upper  third  of  the  anterior  intertrochanteric  ridge,  from  the  rough 
line  leading  from  the  greater  trochanter  to  the  linea  aspera  external 
to  the  gluteus  maximus,  from  the  outer  lip  of  the  linea  aspera  nearly 
down  to  the  external  condyle,  and  also  slightly  from  the  external 
intermuscular  septum.  From  this  origin  the  fibres  pass  downwards,, 
forwards,  and  inwards,  and  end  in  a  flattened  tendon,  which  is. 
inserted  into  the  outer  border  of  the  patella  to  form  part  of  the 
common  extensor  tendon  to  be  presently  described. 

The  vastus  internus  and  crureus  should  be  described  as  one 
muscle,  for  they  are  inseparably  connected.  They  arise  conjointly 
by  an  aponeurosis  commencing  a  short  distance  below  the  inner 
two-thirds  of  the  anterior  intertrochanteric  ridge,  from  the  upper 
three-fourths  of  the  front  and  inner  surfaces  of  the  shaft  of  the 
femur,  from  the  entire  length  of  the  inner  lip  of  the  linea  aspera, 
and  from  the  internal  intermuscular  septum.  The  outer  bundle  of" 
muscular  fibres — the  crureus — passes  vertically  downwards ;  the 
inner — the  vastus  internus — descends  forwards  and  outwards,  and 
both  are  inserted  by  a  common  aponeurosis  into  the  upper  and  the 

1  An  accurate  description  of  this  muscle  is  given  by  W.  E.  Williams,  Journ.  of 
Anat.  and  Phys.,  vol.  xiii.  p.  204,  in  which  he  states  that  the  reflected  head  of  the 
rectus  is  its  real  origin,  as  it  alone  exists  in  early  foetal  life. 


EXTENSOR   MUSCLES.  635 

inner  borders  of  the  patella.  The  muscular  fibres  of  the  vastus 
internus  extend  lower  than  those  of  the  vastus  externus. 

A  few  of  the  deeper  fibres  of  the  crureus  are  inserted  into  the 
fold  of  the  synovial  membrane  of  the  knee-joint  which  rises  above 
the  patella.  These  are  described  as  a  distinct  muscle,  under  the 
name  of  the  sub-crureus.  Their  use  is  to  raise  the  synovial  mem- 
brane, so  that  it  may  not  be  injured  by  the  play  of  the  patella. 
Since  the  triceps  is  connected  to  the  lower  part  of  the  shaft  of  the 
femur  only  by  loose  connective  tissue,  there  is  nothing  to  prevent 
the  distension  of  the  synovial  membrane,  in  cases  of  inflammation, 
to  the  extent  of  several  inches  above  the  patella. 

COMMON  The  tendon  of  the  rectus,  gradually  expanding^ 

EXTENSOR  becomes  connected  on  its  under  surface  with  the 

TENDON.  tendon  of  the  crureus,  and  on  either  side  with  that 

of  the  vasti,  and  is  firmly  fixed  into  the  upper  part  and  sides  of  the 
patella.  From  this  bone  the  common  extensor  tendon — the  lifja- 
mentum  patellce — descends  over  the  front  of  the  knee-joint,  and  is 
inserted  into  the  rough  part  of  the  tubercle  of  the  tibia.  Besides 
this,  the  lower  fibres  of  the  vasti  terminate  on  a  sheet-like  tendon, 
which  runs  wide  of  the  patella  on  either  side,  and  is  directly  inserted 
into  the  sides  of  the  head  of  the  tibia  and  fibula,  so  that  the  knee 
is  completely  protected  all  round.  The  patella  is  a  large  sesamoid 
bone,  interposed  to  facilitate  the  play  of  the  tendon  over  the  con- 
dyles  of  the  femur :  it  not  only  materially  protects  the  joint,  but 
adds  to  the  power  of  the  extensor  muscles,  by  increasing  the  angle 
at  which  the  tendon  is  inserted  into  the  tibia. 

To  facilitate  the  play  of  the  extensor  tendon  there  are  two 
bursae.  One  is  placed  between  the  ligamentuni  patellae  arid  the 
smooth  part  of  the  tubercle  of  the  tibia,  the  other  between  the 
crureus  and  the  lower  part  of  the  femur.  This  last  is  of  consider- 
able size.  In  early  life  it  is,  as  a  rule,  distinct  from  the  synovial 
membrane  of  the  knee-joint ;  but  after  a  few  years  a  wide  commu- 
nication frequently  exists  between  them. 

ACTION  OF  The  extensor  muscles  of  the  thigh  are  among 

THE  EXTENSOR          the  most  powerful  in  the  body.     Great  power  of 
extending  the  knee  is  one  of  the  essential  con- 
ditions of  the  erect  attitude.     Without  it,  how  could  we  rise  from 


•636  BUKSA   OVER   THE   PATELLA. 

the  sitting  position  ?  When  erect,  how  could  we  walk,  run,  or 
spring  ?  The  rectus,  by  taking  origin  from  the  pelvis,  gains  a 
double  advantage  :  it  acts  upon  two  joints  simultaneously,  bending 
the  thigh  while  it  extends  the  knee,  as  when  we  advance  the  leg  in 
walking ;  it  also  contributes  to  balance  the  pelvis  on  the  head  of 
the  thigh-bone,  and  thus  prevents  the  body  from  falling  backwards. 
We  cannot  have  a  better  proof  of  the  power  of  the  extensor  muscles 
than  when  the  patella  is  broken  by  their  sudden  contraction — an 
injury  which  sometimes  happens  when  a  man,  slipping  backwards, 
makes  a  violent  effort  to  recover  his  balance. 

BUKSA  OVER  The  skin  over  the  patella  is  exceedingly  loose, 

THE  PATELLA.  and  in  the  subcutaneous  tissue  is  a  bursa  of  con- 

siderable size.  Since  this  bursa  is  apt  to  enlarge  and  inflame  in 
females  who  are  in  the  habit  of  kneeling  at  their  work,  it  is  gener- 
ally called  the  housemaid's  bursa.  The  bursa  is  not  seated  precisely 
over  the  patella,  but  extends  some  way  down  the  ligamentum 
patellse ;  indeed,  in  some  cases  it  is  entirely  confined  to  this  liga- 
ment. This  corresponds  with  the  position  of  the  tumour  which  the 
bursa  occasions  when  enlarged.  Generally  speaking,  in  subjects 
brought  for  dissection,  the  wall  of  the  bursa  is  more  or  less  thickened, 
and  its  interior  intersected  by  numerous  fibrous  cords,  remnants  of 
the  original  cellular  structure  altered  by  long-continued  friction. 
Again,  the  wall  of  the  bursa  does  not  always  form  a  complete  sac  ; 
sometimes  there  is  a  wide  opening  in  it ;  this  explains  the  rapidity 
with  which  inflammation,  in  some  cases,  extends  from  the  bursa 
into  the  surrounding  areolar  tissue. 

Below  the  bursa  is  a  layer  of  fascia  lata,  and  under  this  is  a 
network  of  arteries.  The  immediate  covering  of  the  bone,  or  what 
may  be  called  its  periosteum,  is  a  strong  expansion  derived  from 
the  extensor  tendon.  This  is  interesting  for  the  following  reason  : 
in  ordinary  fractures  of  the  patella  from  muscular  action  the  ten- 
dinous expansion  over  it  is  torn  also  ;  the  ends  of  the  bone  gape 
widely,  and  never  unite  except  by  ligament.  But  in  fractures  from 
direct  mechanical  violence,  the  tendinous  expansion,  being  entire, 
maintains  the  fragments  in  apposition,  so  that  there  is  commonly  a 
bony  union. 

The  remaining  part  of  the  femoral  artery  can  now  be  examined 
after  the  sartorius  has  been  cut  through  near  its  middle,  and  both 


HUNTER'S  CANAL.  637 

ends  reflected.  This  part  of  its  course  corresponds  to  the  middle 
third  of  the  thigh,  and  is  contained  in  Hunter's  canal. 

FEMORAL  ^n  fron^  of  the  artery  are  the  skin,  superficial 

ARTERY  IN  and  deep  fascias,  the  long  saphena  vein,  the  sarto- 

HUNTER'S  CANAL.  riug}  the  long  saphenous  nerve,  and  the  aponeurotic 
layer  forming  the  anterior  boundary  of  Hunter's  canal :  to  its  outer 
side,  are  the  femoral  vein  and  the  vastus  internus ;  to  its  inner  side> 
are  the  adductor  longus,  the  adductor  magnus  and  the  sartorius ; 
Iteliind  it,  are  the  adductor  longus,  the  femoral  vein,  and  the  ad- 
ductor magnus.  The  artery  and  vein  lie  close  together,  and  are 
enclosed  in  a  common  sheath, 

HUNTER'S  In  the  middle  third  of  the  thigh,  the  femoral 

CANAL.  artery  is  contained  in  a  tendinous  canal l  beneath 

the  sartorius,  called  Hunter's  canal.     This  canal  at  its  upper  part 
is  rather  indistinct ;  but  it  gradually  becomes 
stronger  towards  the  opening  in  the  tendon  FIG.  150. 

of  the  adductor  magnus.     Its  boundaries  are 
formed  by  the  tendons  of  the  muscles  be- 
tween which  the  artery  runs.     On  the  inner 
side  are  the  tendons  of  the  adductor  longus 
and  magnus  ;  on  the  outer  side  is  the  tendon 
of  the  vastus  internus ;  in  front  the  canal          SECTION  THROUGH 
is    completed  by  an  aponeurotic  expansion          HUNTER'S  CANAL. 
thrown  obliquely  across  from  the  adductors     i.  vastus  internus. 

,••  j.        •    i.  i  •      .c        i  K  A         2.  Adductor  longus. 

to  the  vastus  internus,  as  shown  in  fig.  150.  3>  Apraeurwis  thrown  acnw. 
In  a  horizontal  section  the  canal  appears  trian- 
gular. The  adaptation  of  this  shape  to  the  exigencies  of  the  case  is 
manifest  when  we  reflect  that  the  muscles  keep  the  sides  of  the 
triangle  always  tight,  and  thereby  prevent  any  compression  of  the 
vessels. 

Hunter's  canal  contains  not  only  the  femoral  artery  and  vein, 
but  the  internal  saphenous  nerve.  The  vein  lies  behind  and  to  the 
outer  side  ;  the  nerve  crosses  over  the  artery  from  the  outer  to  the 
inner  side. 

1  Called  Hunter's  canal,  because  it  was  in  this  part  of  its  course  that  John 
Hunter  first  tied  the  femoral  artery  for  aneurism  of  the  popliteal,  in  St.  George's 
Hospital,  A.D.  1785.  The  particulars  of  this  interesting  case  are  published  in  the 
Trans,  for  the  Improvement  of  Med.  and  Chir.  Knowledge. 


638  BRANCHES  OF  THE  FEMORAL  ARTERY. 

A  ligature  can  be  placed  around  the  artery,  in  the  upper  third 
of  the  thigh,  with  comparative  facility ;  not  so  easily  in  the  middle 
third.  The  artery  is  tied  for  an  aneurism  of  the  popliteal,  just 
where  the  sartorius  begins  to  overlap  it,  for  three  reasons  :  (1)  it 
is  more  accessible  ;  (2)  the  coats  of  the  artery  at  this  distance  are 
less  likely  to  be  diseased ;  (3)  the  origin  of  the  profunda  is  suffi- 
ciently far  off  to  admit  of  the  formation  of  a  clot.  An  incision, 
beginning  about  three  inches  below  the  crural  arch,  should  be 
made  about  three  inches  long  over  the  line  of  the  artery.  The 
muscular  fascia  should  be  divided  on  a  director  to  the  same  extent. 
Then,  by  gently  drawing  aside  the  inner  border  of  the  sartorius, 
the  artery  is  seen  enclosed  in  its  sheath  with  the  vein.  An  open- 
ing should  be  made  into  the  sheath,  which  must  be  carefully 
separated  from  the  artery  to  an  extent  sufficient  to  allow  the 
passage  of  the  aneurismal  needle.  The  needle  should  be  turned 
round  the  artery  from  within  outwards,  great  care  being  taken  not 
to  injure  the  vein.  The  nerves  to  be  avoided  are — the  long 
saphenous,  which  runs  along  the  outer  side  of  the  artery,  and  the 
internal  cutaneous  which  crosses  obliquely  over  it. 

Having  already  traced  the  superficial  branches  of  the  femoral 
artery  in  the  groin,  namely,  the  superficial  epigastric,  the  external 
pudic,  and  the  superficial  circumflexa  ilii  (p.  611),  we  pass  on  now 
to  the  profunda. 

PKOFUNDA  The  profunda  femoris,  the  chief  branch  of  the 

AKTEBY  AND  femoral,    is   the   proper    nutrient   artery   of    the 

BRANCHES.  muscles    of  the   thigh,    and   is    considered    as    a 

division,  rather  than  a  branch,  of  the  common  femoral  artery.  It 
is  given  off  from  the  outer  and  back  part  of  the  femoral,  from  one 
and  a  half  to  three  inches  below  the  crural  arch,  lying  to  the  outer 
side  of  the  artery  for  about  two  inches,  and  then  runs  down  behind 
the  femoral  till  it  reaches  the  tendon  of  the  adductor  longus ;  here 
the  profunda  passes  behind  the  adductor,  and  piercing  the  adductor 
magnus  as  a  small  branch,  is  finally  lost  in  the  hamstring  muscles.1 

1  The  point  at  which  the  profunda  is  given  off  below  the  crural  arch  varies  very 
much  even  in  the  two  limbs  of  the  same  body.  We  have  measured  it  in  19  bodies, 
or  38  femoral  arteries.  It  varied  from  half  an  inch  to  3  inches.  In  22  cases  the 
profunda  came  off  between  H  and  2  inches  ;  in  9  this  distance  was  exceeded  ;  in  7 
this  distance  was  less. 


BRANCHES  OF  THE  PROFUNDA  FEMORIS.         639 

In  most  subjects  the  profunda,  for  a  short  distance  after  its  origin, 
lies  rather  on  the  outer  side  of  the  femoral  and  on  a  deeper  plane, 
on  the  iliacus  :  in  this  situation  it  might  be  mistaken  for  the  super- 
ficial femoral  itself — indeed,  such  an  error  has  occurred  in  practice. 
It  soon,  however,  gets  behind  the  femoral,  and  lies  upon  the  pecti- 
neus,  the  adductor  brevis  and  magnus  ;  it  is  separated  from  the 
femoral  artery,  at  first,  by  their  corresponding  veins ;  lower  down, 
by  the  adductor  longus. 

The  branches  of  the  profunda  generally  arise  in  the  following 
order  :  (1)  the  internal  circumflex ;  (2)  the  external  circumflex ; 
(3)  the  perforating. 

The  internal  circumflex  is  given  off  from  the  inner  and  back  part  of 
the  profunda,  and  then  sinks  deeply  into  the  thigh  between  the  psoas 
and  pectineus.  At  the  lower  border  of  the  obturator  externus  it  divides 
into  two  branches  :  one — the  ascending — supplies  the  muscles  in  its 
neighbourhood,  namely,  the  pectineus,  psoas,  adductors,  gracilis,  and 
obturator  externus,  anastomosing  with  the  obturator  artery  ;  the  other 
— the  descending — passes  down  to  behind  the  adductor  brevis  to  supply 
it  and  the  adductor  magnus  ;  the  continuation  of  the  artery  called  the 
transverse,  will  be  seen  in  the  dissection  of  the  back  of  the  thigh, 
between  the  adductor  magnus  and  the  quadratus  femoris.  This  latter 
sometimes  gives  off  a  small  branch  to  the  hip-joint,  which  runs  through 
the  notch  in  the  acetabulum  to  the  ligamentum  teres  ;  it  afterwards 
inosculates  with  the  sciatic,  the  external  circumflex  and  superior 
perforating  arteries,  forming  the  crucial  anastomosis. 

The  external  circumflex  artery  comes  off  from  the  outer  side  of  the 
profunda,  runs  transversely  outwards  beneath  the  sartorius  and  rectus 
between  the  branches  of  the  anterior  crural  nerve,  and  then  subdivides 
into  three  sets  of  branches,  ascending,  transverse,  and  descending.  The 
ascending  run  up  to  the  outer  side  of  the  ilium,  beneath  the  tensor  fascife 
and  gluteus  medius,  supply  these  muscles,  and  inosculate  with  the  termi- 
nal branches  of  the  gluteal  and  deep  circumflex  iliac  arteries.  The 
transverse  pass  directly  outwards  over  the  crureus,  then  enter  the  vastus 
externus,  and  get  between  the  muscle  and  the  femur.  They  inosculate 
with  the  sciatic,  the  internal  circumflex,  the  gluteal,  and  the  perforating 
arteries.  The  descending,  two  or  more  in  number,  of  considerable  size, 
run  down  between  the  rectus  and  crureus,  and  supply  both  these 
muscles  :  one  branch,  larger  than  the  rest,  runs  down  in  the  substance 


640 


BKANCHES    OF   THE    PROFUNDA    FEMORIS. 


of  the  vastus  externus,  along  with  the  nerve  to  that  muscle,  and  inos- 
culates with  the  superior  articular  branches  of  the  popliteal. 

The  perforating  branches  of  the  profunda  are  so  named  because  they 
pass  through  the  adductors  to  supply  the  hamstring  muscles.  There  are 
generally  four.  The  first  passes  between  the  pectineus  and  the  adductor 
brevis,  then  pierces  the  adductor  magnus,  and  communicates  with  the 

FIG.  151. 


1.  Crural  arch. 

2.  Internal  iliac. 

3.  Superficial  femoral. 

4.  Profuuda. 

5.  Internal  circumflex. 

6.  External  circumflex. 


7.  First  perforating. 

8.  Second  ditto. 

9.  Third  ditto. 

10.  Gluteal. 

11.  Obturator. 

12.  Sciatic. 

13.  A.nastomotica  mag 


PLAN    OF    THE    INOSCULATIONS    OF    THE    CIRCUMFLEX    ARTERIES. 

internal  and  external  circumflex,  the  sciatic  and  second  perforating 
arteries.  The  second,  the  largest,  passes  through  the  tendons  of  the 
adductor  brevis  and  magnus,  divides  into  an  ascending  and  a  descending 
branch,  which  anastomose  respectively  with  the  first  and  third  perfora- 
ting arteries.  It  usually  furnishes  the  nutrient  artery  of  the  femur. 
The  third,  given  off  below  the  adductor  brevis,  passes  through  the 
tendon  of  the  adductor  magnus.  The  fourth,  or  terminal  branch,  passes 


ARTERIAL  INOSCULATIONS.  641 

through  the  tendon  of  the  adductor  magnus,  and  supplies  the  hamstring 
muscles,  and  inosculates  with  the  perforating  and  articular  arteries. 
They  not  only  supply  the  hamstring  muscles — namely,  the  biceps,  semi- 
tendinosus,  and  semimembranosus — but,  the  vastus  externus,  and  even 
the  gluteus  maximus.  The  perforating  arteries  inosculate  with  one 
another,  with  the  internal  and  external  circumflex,  and  with  the  sciatic 
arteries. 

Muscular  branches,  from  four  to  seven  in  number,  are  distributed 
by  the  superficial  femoral  to  the  sartorius  and  the  vastus  internus. 
The  anastomotica  magna  arises  from  the  femoral  artery  just 
before  it  leaves  its  tendinous  canal.  It  emerges  through  the  canal, 
and  runs  in  front  of  the  tendon  of  the  adductor  magnus,  in  company 
with  the  long  saphenous  nerve  to  the  inner  side  of  the  knee.  Here 
it  divides  into  two  branches  :  one,  the  superficial,  accompanies  the 
saphenous  nerve  beneath  the  sartorius,  and  is  subsequently  distri- 
buted to  the  skin  ;  the  other,  the  deep,  enters  the  vastus  internus, 
ramifies  over  the  capsule,  and  communicates  with  the  other  articular 
arteries.1 

ARTERIAL  If  the   common   femoral  were   tied   above  the 

INOSCULATIONS.  origin  of  the  profunda,  how  would  the  circulation 
be  carried  on  ?  The  gluteal,  the  ilio-lumbar,  and  the  circumflex 
iliac  communicate  with  the  ascending  branch  of  the  external  cir- 
cumflex ;  the  obturator  and  sciatic  communicate  with  the  internal 
circumflex  (see  fig.  151)  ;  the  arteria  comes  nervi  ischiatici  com- 
municates with  branches  from  the  lower  perforating  and  popliteal 
arteries.  Again,  how  is  the  circulation  maintained  when  the  super- 
ficial femoral  is  tied  below  the  profunda  ?  The  descending  branch 
of  the  external  circumflex  and  the  perforating  branches  of  the  pro- 
funda communicate  with  the  articular  branches  of  the  popliteal  and 
the  tibial  recurrent.2 

ANTERIOR  Tne  anterior  crural  nerve  is  the  largest  branch 

CRURAL  NERVE.         of  the  lumbar  plexus  (p.  498).  It  comes  from  the 

1  In  its  course  down  the  thigh  the  femoral  artery  gives  off  a  branch  of  con- 
siderable size  for  the  supply  of  the  vastus  internus.     We  may  trace  this  branch 
through  the  substance  of  the  vastus  down  to  the  patella,  where  it  joins  the  network 
of  vessels  on  the  surface  of  that  bone. 

2  Read  the  account  of  the  dissection  of  an  aneurismal  limb  by  Sir  A.  Cooper, 
Med.  Chir.  Trans,  vol.  ii.,  1811. 

T  T 


642  ANTERIOR  CRURAL  NERVE. 

third  and  fourth  lumbar  nerves,  also  by  a  small  fasciculus  from  the 
second.  It  passes  beneath  the  crural  arch,  lying  in  the  groove 
between  the  iliacus  and  psoas,  about  a  quarter  of  an  inch  to  the 
outer  side  of  the  artery,  and  soon  divides  into  branches,  some  of 
which  are  cutaneous,  but  the  greater  number  supply  the  extensor 
muscles  of  the  thigh.  The  cutaneous  branches,  already  described 
(p.  614),  and  the  long  saphenous  'nerve,  are  given  off  from  the 
superficial  part  of  the  trunk  ;  the  muscular  from  the  deep  part. 

The  long  saphenous  nerve,  the  largest  of  the  cutaneous  branches,, 
descends  close  to  the  outer  side  of  the  femoral  artery,  and  enters  the 
tendinous  canal  with  it  in  the  middle  third  of  the  thigh.  In  the  canal 
it  crosses  over  the  artery  to  its  inner  side.  The  nerve  leaves  the  artery 
just  before  it  becomes  popliteal,  and  then  runs  in  company  with  the 
anastomotica  magna  to  the  inner  side  of  the  knee,  where  it  becomes 
superficial,  between  the  gracilis  and  the  sartorius.  In  the  middle  third 
of  the  thigh  it  gives  off  a  small  branch  which  communicates  beneath 
the  fascia  lata  with  the  internal  cutaneous  and  obturator  nerves  ;  and 
lower  down  another  branch  is  distributed  to  the  skin  over  the  patella. 
Its  further  relations  will  be  seen  in  the  dissection  of  the  leg  and  foot. 

The  imiscular  branches  are  to  be  traced  to  the  sartorius,  rectus, 
crureus,  and  subcrureus  ;  the  branch  to  the  vastus  externus  accompanies 
the  descending  branch  of  the  external  circumflex  artery,  and  sends  a 
filament  to  the  knee-joint ;  that  to  the  vastus  internus  runs  parallel 
with,  but  external  to,  the  long  saphenous  nerve,  and  supplies  filaments 
to  the  knee-joint.  One  branch,  often  two,  passes  under  the  femoral 
artery  and  vein  to  enter  the  anterior  surface  of  the  pectineus. 

The  obturator  nerve,  also  a  branch  of  the  lumbar  plexus,  arising 
from  the  second,  third,  and  fourth  lumbar  nerves  (p.  498),  supplies 
the  adductor  muscles.  It  enters  the  thigh  through  the  upper  part 
of  the  obturator  foramen  above  the  corresponding  artery,  and  im- 
mediately divides  into  two  branches,  of  which  one  passes  in  front 
of,  the  other  behind,  the  adductor  brevis.  The  anterior  branch 
subdivides  for  the  supply  of  the  gracilis,  the  adductor  longus,  and 
sometimes  the  adductor  brevis  and  pectineus  ;  it,  moreover,  sends 
a  filament  to  the  hip-joint ;  another  to  the  femoral  artery ;  and  a 
third  forms  a  plexiform  communication  at  the  lower  border  of  the 
adductor  longus  with  the  internal  cutaneous  and  long  saphenous 
nerves.  The  posterior  branch  supplies  the  obturator  externus,  the 


DISSECTION   OF   THE   FRONT   OF   THE   LEG.  643 

adductor  brevis  and  magnus.  In  some  bodies  you  can  trace  a  fila- 
ment of  this  nerve  through  the  notch  of  the  acetabulum  into  the 
hip-joint,  and  another,  which  runs  near  the  popliteal  artery,  into 
the  back  part  of  the  knee-joint.  We  have  frequently  seen  cutaneous 
branches  from  the  obturator  on  the  inner  side  of  the  thigh.  This 
is  interesting  practically,  since  it  helps  to  explain  the  pain  often 
felt  on  the  inner  side  of  the  knee  in  disease  of  the  hip-joint. 

The  accessory  obturator  nerve,  when  present,  comes  either  from 
the  obturator  nerve  or  from  the  third  and  fourth  lumbar  nerves. 
Descending,  it  runs  between  the  horizontal  ramus  of  the  os  pubis 
and  the  pectineus,  and  supplies  a  branch  to  this  muscle,  also  a  fila- 
ment of  communication  to  the  anterior  branch  of  the  obturator, 
and  a  third  branch  to  the  hip-joint. 

The  obturator  artery,  after  passing  through  the  foramen,  divides 
into  two  branches,  an  internal  and  an  external,  which  form  a  circle 
round  the  obturator  membrane.  These  supply  the  external  obtu- 
rator and  adductors  of  the  thigh,  and  inosculate  with  the  internal 
circumflex  artery  (p.  640).  The  latter  branch  sometimes  gives  off 
the  small  artery  to  the  ligamentum  teres  of  the  hip-joint. 


DISSECTION   OF   THE   FBONT   OF   THE   LEG. 

SURFACE  About  an  inch  below  the  patella  is  the  promi- 

MABKING.  nent  tubercle  of  the  tibia,  to  which  the  ligamentum 

patellae  is  attached ;  on  each  side  of  this  is  a  depression,  filled  with 
more  or  less  fat.  About  the  same  distance  below  the  outer  tubero- 
sity  of  the  tibia  is  the  head  of  the  fibula,  situated  far  back,  and  to 
it  can  be  traced  the  tense  tendon  of  the  biceps.  The  crest  of  the  tibia- 
is  easily  felt  in  front,  commencing  above  at  the  outer  tuberosityr 
and  passing  down  nearly  vertically,  gradually  inclining  to  the  inner 
side  so  that  it  is  continuous  below  with  the  front  of  the  internal 
malleolus.  Internal  to  the  crest  is  the  subcutaneous  internal  surface 
of  the  tibia,  and  externally  is  the  interval  between  the  tibia  and 
the  fibula,  which  is  filled  up  by  the  extensor  muscles.  The  lower 
fourth  of  the  fibula  is  subcutaneous,  ending  in  a  well-marked 
prominence,  the  external  malleolus,  which,  it  should  be  observed, 

T  T   2 


644       CUTANEOUS  VEINS  AND  NERVES  OF  THE  LEG. 

descends  lower  than  the  internal  malleolus.  The  student  should 
notice  well  the  tendons  which  surround  the  ankle-joint,  which 
are  easily  recognisable  under  the  skin  :  thus,  behind,  the  tendo 
•Achillis  stands  out  prominently,  having  a  deep  depression  on  each 
side  ;  on  the  outer  side,  the  tendons  of  the  peronei,  longus  and 
brevis,  are  felt,  the  latter  being  the  anterior.  Running  round  the 
inner  ankle  we  can  only  feel  the  tibialis  posticus  close  to  the  tibia, 
and  next  to  it  the  flexor  longus  digitorum  ;  in  front  of  the  ankle, 
but  bound  down  by  the  anterior  annular  ligament,  can  be  felt,  from 
within  outwards,  the  strong  tendon  of  the  tibialis  anticus,  the 
extensor  proprius  hallucis,  and  the  long  extensor  of  the  toes  with 
the  peroneus  tertius. 

The  foot  should  be  turned  inwards,  and  fixed  in  this  position. 
An  incision  must  be  made  from  the  knee,  down  the  front  of  the 
leg,  over  the  ankle,  along  the  top  of  the  foot  to  the  great  toe  ;  a 
second,  at  right  angles  to  the  first,  on  either  side  of  the  ankle  ;  a 
third,  across  the  bases  of  the  toes.  Reflect  the  skin  from  the  front 
and  sides  of  the  leg  and  foot. 

CUTANEOUS  Having  traced  the  internal  saphena  vein  (p.  613) 

VEINS  AND  to  the  inner  side  of  the  knee,  follow  it  down  the 

NEEVES.  inner  side  of  the  leg,  in  front  of  the  inner  ankle  l 

to  the  dorsum  of  the  foot.  On  the  dorsum  of  the  foot  notice  that 
the  principal  veins  form  an  arch,  with  the  convexity  forwards,  as 
on  the  back  of  the  hand.  This  arch  receives  the  veins  from  the 
toes.  From  the  inner  side  of  the  arch  the  internal  saphena 
originates  ;  from  the  outer  side,  the  external  saphena.  The  latter 
vein  commences  on  the  outer  side  of  the  arch  on  the  dorsum,  runs 
behind  the  external  ankle,  along  the  outer  border  of  the  tendo 
Achillis  up  the  back  of  the  calf  of  the  leg,  between  the  two  heads 
of  the  gastrocnemius,  and  finally  pierces  the  deep  fascia  at  the  lower 
part  of  the  popliteal  space,  to  join  the  popliteal  vein.  The  external 
saphenous  nerve  accompanies  this  vein,  as  the  long  saphenous  nerve 
does  the  internal  saphena  vein. 

LONG  SAPHE-  The  skin  on  the  inner  side  of  the  leg  is  supplied 

NOUS  NERVE.  by  the  long  or  internal  saphenous  nerve  (p.  642). 

1  The  French  commonly  bleed  from  the  internal  saphena  vein  as  it  crosses  over 
the  inner  ankle,  this  being  a  convenient  and  safe  place  for  venesection. 


MUSCULAR  FASCIA  AND   ANNULAK   LIGAMENTS.  645 

It  becomes  subcutaneous  on  the  inner  side  of  the  knee,  between  the 
gracilis  and  sartorius.  Here  it  meets  the  saphena  vein,  and  ac- 
companies it  down  the  leg,  distributing  its  branches  on  either  side, 
till  it  is  finally  lost  on  the  inner  side  of  the  foot  and  the  great  toe. 
The  largest  branch  curves  round  the  inner  side  of  the  knee,  just 
below  the  patella,  to  supply  the  skin  in  this  situation.  It  pierces 
the  sartorius  close  to  the  knee,  and  forms  with  branches  from  the 
internal,  middle,  and  external  cutaneous  nerves,  the  plexus  patellce. 
The  internal  cutaneous  nerve  supplies  the  skin  of  the  upper  and 
inner  aspect  of  the  leg,  and  joins  the  internal  saphenous  nerve. 

The  skin  on  the  front  and  outer  parts  of  the  upper  half  of  the 
leg  is  supplied  by  cutaneous  brandies  from  the  external  popliteal  or 
peroneal  nerve  ;  the  skin  of  the  lower  half  by  its  external  cutaneous 
branch,  as  follows  : — 

EXTERNAL  Cu-  This  branch  of  the  peroneal  nerve  comes  through 

TANEOUS  BBANCH  the  fascia  about  the  lower  third  of  the  outer  side 
OF  THE  PERONEAL  of  the  leg ;  and,  descending  over  the  front  of  the 
ankle,  divides  into  two.  Trace  them  and  you  will 
find  that  the  inner  and  smaller  supplies  the  inner  side  of  the  great 
toe,  and  the  contiguous  sides  of  the  second  and  third  toes  ;  towards 
its  termination  it  communicates  with  the  long  saphenous  and  an- 
terior tibial  nerves.  The  outer  distributes  branches  to  the  outer 
side  of  the  third  toe,  both  sides  of  the  fourth,  and  the  inner  side  of 
the  fifth  toe,  and  joins  the  short  or  external  saphenous  nerve. 

The  outside  of  the  little  toe  is  supplied  by  the  external  saphenous 
nerve,  which  runs  behind  the  outer  ankle  with  the  corresponding 
vein. 

The  contiguous  sides  of  the  great  and  second  toes  are  supplied 
by  the  termination  of  the  anterior  tibial  nerve.1 

MUSCULAR  This  is  remarkably  thick  and  strong.     Besides 

FASCIA  AND  AN-         its  general  purpose  of  forming   sheaths  for   the 
NULARLiGA-  muscles,   and   straps   for   the   tendons,    it    gives 

origin,  as  in  the  forearm,  to  muscular  fibres;  so- 
that  it  cannot  be  removed  near  the  knee  without  leaving  the 
muscles  ragged.  The  fascia,  continuous  above  with  the  fascia  lata, 

1  Such  is  the  most  common  distribution  of  the  nerves  to  the  upper  surface  of 
the  toes.    But  deviations  from  this  arrangement  are  frequent. 


646  THE   ANNULAR   LIGAMENTS. 

is  attached  to  the  head  of  the  tibia  and  the  fibula :  it  is  connected 
on  the  inner  side  with  the  expanded  tendons  of  the  sartorius, 
gracilis,  and  semi-tendinosus ;  on  the  outer  side  with  that  of  the 
biceps :  consequently,  when  these  muscles  act,  it  is  rendered  tense. 
Following  it  down  the  leg,  you  find  that  it  is  attached  to  the  edge 
of  the  tibia,  and  that  it  becomes  stronger  as  it  approaches  the 
ankle,  to  form  the  ligaments  which  confine  the  tendons  in  this 
situation.  Of  these  ligaments,  called  annular,  there  are  three,  as 
follows : — 

a.  The  anterior  annular  ligament  extends  obliquely  across  the 
front  of  the  ankle-joint,  and  confines  the  extensor  tendons  of  the 
ankle  and  toes.     It  consists  of  two  converging  straps — one  oblique, 
the  other  horizontal,  which  join,  and  are  continued  on  as  a  common 
band,  like  the  letter  H<  placed  transversely :  the  upper  or  oblique 
binds  down  the  tendons  in  front  of  the  lower  end  of  the  tibia ;  the 
lower  or  oblique  the  tendons  which  lie  over  the  tarsus.  The  common 
band  is  attached  to  the  external  malleolus,  cuboid,  and  os  calcis ; 
it  is  continued  horizontally  inwards  for  a  short  distance,  and  in 
front  of  the  ankle  splits  into  two  fasciculi :  the  upper  or  oblique 
-ascends  to  be  attached  to  the  tibia ;  the  lower  or  horizontal  passes 
inwards  to  be  attached  to  the  internal  malleolus,  the  scaphoid,  and 
the  internal  cuneiform.     Beneath  the  upper  fasciculus,  enclosed  in 
two  synovial  sheaths,  run  the  tibialis  anticus  on  the  inner  side, 
and  the  extensor  longus  digitorum  and  peroneus  tertius  on  the 
outer  side ;  the  extensor  proprius  hallucis  and  the  anterior  tibial 
vessels  lying  behind  the  ligament,  but  not  having  any  synovial 
sheath.     Beneath  the  lower  fasciculus  are  three  synovial  sheaths — 
an  inner  one  for  the  tibialis  anticus,  a  middle  one  for  the  extensor 
proprius  hallucis,  and  an  outer  one  for  the  extensor  longus  digi- 
torum and  peroneus  tertius.     It  is  the  strain  of  this  ligament  which 
occasions  the  pain  in  sprains  of  the  ankle. 

b.  The    external    annular    ligament    extends   from    the    outer 
malleolus  to  the  os  calcis,  and  confines  the  tendons  of  the  peronei 
muscles,  which  are  enclosed  in  a  common  synovial  sheath. 

c.  The  internal  annular  ligament  is  a  strong  fasciculus  of  ill- 
•defined  fibrous  tissue  which  extends  from  the  inner  malleolus  to 
the  os  calcis,  where  it  becomes  continuous  with  the  plantar  fascia 


MUSCLES  ON  THE  FRONT  OF  THE  LEG.          647 

and  the  tendinous  origin  of  the  abductor  hallucis.  It  binds  down 
the  flexor  tendons  of  the  foot  and  toes,  and,  as  these  pass  round 
the  inner  ankle,  it  forms  three  compartments,  each  lined  with  a 
separate  synovial  sheath — one  each  for  the  tibialis  posticus,  the 
flexor  longus  digitorum,  and  the  flexor  longus  hallucis. 

Remove  the  fascia,  leaving  enough  of  the  annular  ligaments  to 
retain  the  tendons  in  their  places. 

MUSCLES  ON  The  muscles  on  the  front  of  the  leg  are  : — (1) 

•THE  FRONT  OF  the  tibialis  anticus  ;  (2)  the  extensor  longus  digi- 

THE  LEG.  torum  and   peroneus   tertius  ;    (3)    the    extensor 

proprius  hallucis. 

TIBIAUS  The  tibialis  anticus  arises  by  fleshy  fibres  from 

ANTICUS.  the  external  tuberosity  and  the  upper  two-thirds 

of  the  outer  side  of  the  shaft  of  the  tibia,  from  the  interosseous 
membrane,  from  the  fascia  which  covers  it,  and  from  the  inter- 
muscular  septum  which  separates  it  from  the  extensor  longus 
digitorum.  About  the  lower  third  of  the  leg  the  fibres  terminate  on 
a  strong  flat  tendon,  which  descends  obliquely  over  the  front  of  the 
ankle,  through  the  innermost  compartment  of  the  anterior  annular 
ligament,  to  the  inner  side  of  the  foot ;  here  it  becomes  a  little 
broader,  and  is  inserted  into  the  internal  cuneiform  bone  and  the 
base  of  the  metatarsal  bone  of  the  great  toe.  The  synovial  mem- 
brane, which  lines  the  sheath  of  the  tendon  beneath  the  anterior 
annular  ligament,  accompanies  it  to  within  an  inch  of  its  insertion ; 
•consequently,  it  is  opened  when  the  tendon  is  divided  for  club-foot. 
The  action  of  this  muscle  is  to  draw  the  foot  upwards  and  inwards.1 
When  the  foot  is  the  fixed  point,  it  assists  in  balancing  the  body 
at  the  ankle.  Its  nerve  comes  from  the  anterior  tibial. 

EXTENSOR  This  muscle  lies  along  the  fibular  side  of  the 

LONGUS  DIGI-  preceding.     It  arises  from  the  external  tuberosity 

-TORUM.  Of  tne  tibia,  from  the  upper  three-fourths  of  the 

anterior  surface  of  the  shaft  of  the  fibula,  from  the  interosseous 
membrane,  from  the  fascia  of  the  leg  and  the  intermuscular  septa. 
Its  fibres  terminate  in  a  penniform  manner  upon  a  long  tendon, 
.situated  on  the  inner  side  of  the  muscle :  this  tendon  descends  in 

1  It  is  generally  necessary  to  divide  this  tendon  in  the  distortion  of  the  foot 
inwards  called  talipes  varus. 


648          MUSCLES  ON  THE  FRONT  OF  THE  LEG. 

front  of  the  ankle  and  divides  into  four  slips,  which  pass  to  the 
four  outer  toes.  They  diverge  from  each  other,  and  are  inserted 
into  the  toes  thus  : — On  the  base  of  the  first  phalanx,  each  tendon 
(except  that  of  the  little  toe)  is  joined  on  its  outer  side  by  the  cor- 
responding tendon  of  the  extensor  brevis,  and  a  little  further  on  by 
a  fibrous  expansion  from  the  interosseous  and  lumbrical  muscles. 
The  united  tendons  then  expand,  cover  the  dorsal  surface  of  the 
first  phalanx,  and  at  the  articulation  between  this  and  the  second 
phalanx,  split  into  three  fasciculi ;  the  middle  one  is  inserted  into- 
the  base  of  the  second  phalanx,  the  two  lateral  ones,  running  on 
and  reuniting,  are  inserted  into  the  base  of  the  third  phalanx. 
Its  nerve  comes  from  the  anterior  tibial. 

Immediately  below  the  ankle  the  anterior  annular  ligament 
forms  a  pulley  through  which  the  tendon  of  this  muscle  plays.  It 
is  like  a  sling,  of  which  the  two  ends  are  attached  to  the  os  calcis, 
while  the  loop  serves  to  confine  the  tendon.  The  play  of  the  ten- 
don is  facilitated  by  a  synovial  membrane,  which  is  prolonged  for 
a  short  distance  along  each  of  its  four  divisions.  Besides  its  chief 
action,  this  muscle  extends  the  ankle-joint.1 

PEKONEUS  This  is  a  portion  of  the  preceding.     Its  fibres 

TEETIUS.  arise  from  the  lower  fourth  of  the  anterior  surface 

of  the  shaft  of  the  fibula,  the  interosseous  membrane,  and  the 
intermuscular  septum  between  it  and  the  peroneus  brevis,  and  ter- 
minate on  their  tendon  like  barbs  on  a  quill.  The  tendon  passes 
through  the  same  synovial  pulley  with  the  long  extensor  of  the 
toes,  and,  expanding  considerably,  is  inserted  into  the  tarsal  end  of 
the  metatarsal  bone  of  the  little  toe.  It  is  not  always  present.  It 
is  supplied  by  a  branch  of  the  anterior  tibial  nerve.  This  muscle 
extends  the  foot  and  draws  the  outer  border  of  the  foot  upwards. 

The  peroneus  tertius  and  the  tibialis  anticus  are  important 
muscles  in  progression.  They  raise  the  toes  and  foot  from  the 
ground.  Those  who  have  lost  the  use  of  these  muscles  are  obliged 
to  drag  the  foot  along  the  ground,  or  to  swing  the  entire  limb 
outwards  in  walking. 

1  There  is  often  a  large  bursa  between  the  tendon  of  the  extensor  longus  digi- 
torum  and  the  outer  end  of  the  astragalus.  This  bursa  sometimes  communicates 
with  the  oint  of  the  head  of  the  astragalus. 


COURSE   AND   RELATIONS   OF  THE   ANTERIOR   TIBIAL   ARTERY.     649* 

EXTENSOR  This  muscle  lies  partly  concealed  between  the 

PEOPKIUS  tibialis  anticus  and  the  extensor  longus  digitorum.. 

HALLUCIS.  j^  ar{ses  from  rather  more  than  the  middle  third 

of  the  anterior  surface  of  the  fibula,  and  from  the  interosseous 
membrane.  The  fibres  terminate  in  a  penniform  manner  on  the 
tendon,  which  runs  over  the  ankle,  between  the  tendons  of  the 
tibialis  anticus  and  the  extensor  longus  digitorum,  along  the  top 
of  the  foot  to  the  great  toe,  where  it  is  inserted  into  the  base  of  the 
last  phalanx.  It  has  a  special  pulley  beneath  the  horizontal 
portion  of  the  anterior  annular  ligament,  lined  by  a  synovial  mem- 
brane, which  accompanies  it  as  far  as  the  metatarsal  bone  of  the 
great  toe.  It  is  supplied  by  the  anterior  tibial,  a  branch  of  the 
peroneal  nerve. 

Now  examine  the  course,  relations,  and  branches  of  the  ante- 
rior tibial  artery.  Since  it  lies  deeply  between  the  muscles,  it 
is  necessary  to  separate  them  from  each  other  :  this  is  easily  done 
by  proceeding  from  the  ankle  towards  the  knee. 

COURSE  AND  ^e  anteri°r  tibial   artery  is    one  of  the    two 

KELATIONS  OF  THE  branches  into  which  the  popliteal  divides  at  the 
ANTERIOR  TIBIAL  lower  border  of  the  popliteus.  It  comes  at  first 
ARTERY.  horizontally  forward  about  1£  inch  below  the 

head  of  the  fibula,  between  the  two  heads  of  the  tibialis  posticus, 
above  the  interosseous  membrane,  and  then  descends,  lying  in 
rather  more  than  the  first  half  of  its  course  upon  the  interosseous 
membrane,  afterwards  along  the  front  of  the  tibia.  It  runs  be- 
neath the  anterior  annular  ligament  over  the  front  of  the  ankle, 
where  it  takes  the  name  of  the  dorsal  artery  of  the  foot.  Thus,  a 
line  drawn  from  the  head  of  the  fibula  to  the  interval  between  the 
first  and  second  metatarsal  bones  would  nearly  indicate  its  course. 
In  the  upper  third  of  the  leg  it  lies  deeply  between  the  tibialis 
anticus  and  the  extensor  longus  digitorum ;  in  the  lower  two-thirds, 
between  the  tibialis  anticus  and  the  extensor  proprius  hallucis. 
In  front  of  the  ankle  the  artery  is  crossed  by  the-extensor  proprius 
hallucis,  and  lies  between  the  tendon  of  this  muscle  and  the  inner 
tendon  of  the  extensor  longus  digitorum. 

The  artery  is  accompanied  by  the  anterior  tibial  nerve  (a, 
branch  of  the  peroneal),  which  runs  for  some  distance  upon  its 


650  ANTERIOR   TIBIAL   ARTERY. 

fibular  side,  then  in  front  of  it,  and  lower  down  is  again  situated 
on  its  outer  side.     It  is  accompanied  by  two  veins,  one  on  each 
side,  which  communicate  at  intervals  by  cross  branches. 
The  branches  of  the  anterior  tibial  are  as  follows  : — 

a.  The  recurrent  tibial  branch  ascends  close  by  the  outer  side  of  the 
head  of  the  tibia,  through  the  tibialis  anticus,  to  the  front  of  the  knee- 
joint,  where  it  inosculates  with  the  other  articular  arteries  derived  from 

the  popliteal,  and  with  the  anastomotica  magna. 

b.  MiLscular  branches,  in  its  course  down  the  leg,  and  others  which 
pierce  the  interosseous  membrane,  and  communicate  posteriorly  with 
branches  of  the  posterior  tibial  and  peroneal  arteries. 

c.  The  malleolar  branches,  external  and  internal,  ramify  over  the 
ankle  :  the  external,  descending  beneath  the  tendon  of  the  extensor 
longus  digitorum  and  peroneus  tertius,  ramifies  on  the  external  malleolus, 
inosculating  with  the  anterior  peroneal  and  the  tarsal  arteries  ;  the 
internal  passes  beneath  the  extensor  proprius  hallucis  and  the  tibialis 
anticus,  and  anastomoses   with  the  posterior  tibial,  with  its  internal 
calcanean  branch,  and  with  the  internal  plantar  artery.     They  supply 
the  joint,  the  articular  ends  of  the  bones,  and  the  sheaths  of  the  tendons 
around  them. 

EXTENSOR  This  muscle  is  situated  on  the  dorsum  of  the 

BEEVIS  DIGI-  foot,   beneath  the  long  extensor  tendons   of  the 

TOEUM.  toes.     It    arises   from    the    outer   part  of  the  os 

calcis,  from  the  external  calcaneo-astragaloid  ligament,  and  from 
the  anterior  annular  ligament.  The  fibres  run  obliquely  over  the 
foot,  and  terminate  in  four  tendons,  which  pass  forwards  to  the 
four  inner  toes.  The  inner  one  and  the  largest  is  inserted  by  an 
expanded  tendon  into  the  base  of  the  first  phalanx  of  the  great  toe; 
the  others  join  the  fibular  side  of  the  long  extensor  tendons  to  be 
inserted  with  them  into  the  second  and  ungual  phalanges.  The 
tendon  to  the  great  toe  crosses  over  the  dorsal  artery  of  the  foot. 
It  is  supplied  by  a  branch  of  the  anterior  tibial  nerve. 

DOKSAL  This  artery,  the    continuation  of  the  anterior 

ABTEKY  OF  tibial,   runs  over  the  instep  to  the  back  of  the . 

THE  FOOT.  interval  between  the  first  and  second  metatarsal 

bones,  where  it  divides  into  two  branches — one,  the  dorsalis  hal- 
lucis, runs  along  the  dorsal  aspect  and  the  first  interosseous  space ; 
the  other,  the  communicating,  sinks  into  the  sole  and  joins  the 


DORSAL  ARTERY  OF  THE  FOOT.  651 

deep  plantar  arch.  On  the  dorsum  of  the  foot  the  artery  lies  upon 
the  astragalus,  the  scaphoid,  and  the  internal  cuneiform  bones, 
.separated  however  from  them  by  their  dorsal  ligaments  ;  in  front, 
the  artery  has  the  skin,  superficial  and  deep  fascise,  the  venous 
arch  across  the  dorsum,  and  the  innermost  tendon  of  the  short 
•extensor  of  the  toes  ;  on  its  outer  side,  it  has  the  extensor  longus  digi- 
torum  and  the  anterior  tibial  nerve  ;  on  its  inner  side,  the  extensor 
proprius  hallucis.  The  dorsal  artery  gives  off  the  following 
branches  :  — 

a.  The  tarsal  branch  arises  near  the  scaphoid  bone,  passes  outwards 
in  an  arched  direction  beneath  the  extensor  brevis  digitorum  towards 
the  outside  of  the  foot,  supplies  the  bones  and  joints  of  the  tarsus,  and 
inosculates  with  the  external  malleolar,  the  peroneal,  the  metatarsal, 
.and  the  external  plantar  arteries. 

6.  The  metatarsal  branch  generally  runs  towards  the  outside  of  the 
foot,  in  front  of  and  parallel  with  the  tarsal  artery,  beneath  the  short 
extensor  tendons,  near  the  bases  of  the  metatarsal  bones,  and  gives  off 
the  three  outer  dorsal  interosseous  arteries.  These  pass  forwards  over 
the  corresponding  interosseous  muscles,  supply  them,  and  then  sub- 
divide to  supply  the  contiguous  sides  of  the  upper  surfaces  of  the  toes. 
The  outer  interosseous  branch,  in  addition  to  giving  off  a  branch  to  the 
fourth  interosseous  space,  gives  off  a  small  branch  to  the  outer  side  of 
the  little  toe.  They  receive,  at  the  back  of  each  interosseous  space,  the 
posterior  perforating  branches  of  the  plantar  arch,  and  at  the  front  of 
each  interosseous  space  they  receive  the  anterior  perforating  branches 
from  the  plantar  digital  arteries. 

c.  The  dorsalis  halhicis  is,  strictly  speaking,  the  artery  of  the  first 
interosseous  space.  It  is  the  continuation  of  the  dorsal  artery  of  the 
foot,  after  it  has  given  off  the  communicating  branch  to  the  sole,  and 
runs  forwards  to  supply  digital  branches  to  the  sides  of  the  great  toe, 
the  inner  side  of  the  second  toe. 


PEKONEI  These  muscles  are  situated  on  the  outer  side  of 

MUSCLES.  the  fibula,  and  are  named,  respectively,  peroneus 

longus  and  brevis. 

PERONEUS  This  arises  from  the  head  and  the  outer  surface 

LONGUS.  of  the  fibula  along  its  upper  two-thirds,  from  the 

deep  fascia  which  covers  it,  and  the  intermuscular  septa.  The 
fibres  terminate  in  a  penniform  manner  upon  a  tendon,  which  runs 


652  PERONEAL   NERVE. 

with  the  peroneus  brevis,  in  a  groove  behind  the  external  malleolus,, 
then  along  the  outer  side  of  the  os  calcis,  and,  lastly,  through  a 
groove  on  the  under  surface  of  the  os  cuboides  deep  into  the  sole. 
It  crosses  the  sole  obliquely  forwards  and  inwards,  and  is  inserted 
into  the  tarsal  end  of  the  metatarsal  bone  of  the  great  toe,  and 
usually  into  the  internal  cuneiform  bone.  In  its  course  through 
these  several  bony  grooves  the  tendon  is  confined  by  a  fibrous 
sheath,  lined  by  a  synovial  membrane.  In  removing  the  meta- 
tarsal bone  of  the  great  toe,  if  possible,  leave  the  attachment  of 
this  tendon,  which  is  usually  inserted  by  means  of  a  sesamoid 
bone.  Its  nerve  comes  from  the  peroneal. 

PERONEUS  This  muscle  lies  beneath   the   preceding.      It 

BREVIS.  arises  from  the  lower  two-thirds  of  the  outer  sur- 

face of  the  fibula,  internal  to  the  preceding  muscle,  and  from  the 
intermuscular  septa.  It  terminates  on  a  tendon  which  runs  be- 
hind the  external  malleolus,  through  the  same  sheath  with  the 
peroneus  longus,  then  proceeds  along  the  outside  of  the  foot,  and 
is  inserted  into  the  dorsal  surface  of  the  tarsal  end  of  the  metatarsal 
bone  of  the  little  toe.  On  the  outside  of  the  os  calcis  there  is  a 
ridge  which  separates  the  tendons  of  the  peronei.  Each  has  a  dis- 
tinct sheath.  The  short  tendon  runs  above,  the  long  one  below 
the  ridge.  Its  nerve  is  from  the  musculo-cutaneous  branch  of  the 
peroneal  nerve. 

The  action  of  the  peronei  is  to  raise  the  outer  side  of  the  foot.1' 
This  movement  regulates  the  bearing  of  the  foot  in  progression,  so- 
as  to  throw  the  principal  part  of  the  weight  on  the  ball  of  the 
great  toe.  Its  action  is  well  exemplified  in  skating.  Again, 
supposing  the  fixed  point  to  be  at  the  foot,  they  tend  to  prevent 
the  body  from  falling  on  the  opposite  side,  as  when  we  balance 
ourselves  on  one  leg. 

PEBONEAL  Near  the  inner  side  of  the  tendon  of  the  biceps 

OB  EXTEBNAL  flexor  of  the  leg,   is  a  large  nerve,  the  external 

POPLITEAL  NERVE,  popliteal  or  peroneal,  a  branch  of  the  great  sciatic. 
By  reflecting  the  upper  part  of  the  peroneus  longus,  you  will  find 
that  this  nerve  runs  round  the  outer  side  of  the  fibula  immediately 

1  In  distortion  of  the  foot  outwards,  called  talipes  valgus,  it  is  generally  neces- 
sary to  divide  the  tendons  of  the  peronei. 


DISSECTION '  OF   THE   GLUTEAL   REGION.  653 

below  its  head,  and,  piercing  the  origin  of  the  peroneus  longus, 
divides  into  two  main  branches — the  anterior  tibial  and  the  rnus- 
culo-cutaneous  nerves.  It  gives  off  several  branches  as  follows  : — 
1.  Articular  branches,  two  in  number  to  the  knee-joint,  which 
pass  in  with  the  external  articular  arteries,  and  a  third  which 
accompanies  the  tibial  recurrent  artery.  2.  Cutaneous  branches, 
two  or  more,  supply  the  skin  on  the  back  and  outer  aspect  of  the 
leg,  and  one,  the  communicans  peronei,  which  joins  the  external 
saphenous  to  supply  the  dorsal  aspect  of  the  outer  side  of  the  little 
toe  :  this  will  be  seen  later  on  in  the  dissection  of  the  back  of  the 
leg.  3.  The  anterior  tibial,  which  accompanies  the  corresponding 
artery  and  supplies  the  muscles  between  which  it  runs — namely, 
the  tibialis  anticus,  extensor  longus  digitorum,  extensor  proprius 
hallucis,  and  peroneus  tertius;  also  the  extensor  brevis  digitorum. 
4.  The  musculo-cutaneous  (p.  645),  which  comes  through  the 
fascia  between  the  peroneus  longus  and  the  extensor  longus 
digitorum.  5.  Branches,  which  supply  the  peronei,  longus  and 
brevis,  muscles. 

If,  then,  the  peroneal  nerve  were  divided  in  the  popliteal  space, 
the  result  would  be  paralysis  of  the  tibialis  anticus,  the  extensors 
of  the  toes,  long  and  short,  and  all  the  peronei. 


DISSECTION   OF  THE   GLUTEAL  EEGION. 

The  body  having  been  placed  on  its  face,  the  pelvis  is  to  be 
raised  to  such  a  height  by  blocks  beneath  it,  that  the  lower  ex- 
tremities hang  down  over  the  end  of  the  table.  Then  rotate  the 
thighs  inwards  as  much  as  possible,  and  cross  them. 

SURFACE  The  bony  prominences  are  very  marked   and 

MASKING.  prominent :  they  are,  on  the  outer  side,  the  great 

trochanter,  and,  on  the  inner,  the  posterior  superior  spine  of  the 
ilium,  the  spines  of  the  sacral  vertebrae,  which  are  continued  on  to 
the  coccyx.  Between  the  latter  bone  and  the  great  trochanter  is 
the  rounded  tuberosity  of  the  ischium,  which  in  the  erect  position 
is  covered  by  the  gluteus  maximus,  but  is  uncovered  by  it  when  the 
femur  is  flexed.  Notice  a  transverse  curved  fold  of  the  skin  extending 


654      CUTANEOUS  NERVES  OF  THE  GLUTEAL  REGION. 

from  the  coccyx  to  the  base  of  the  great  trochanter,  which  does 
not,  as  it  might  be  thought,  correspond  with  the  lower  border 
of  the  glutens  maximus,  which  is  much  lower.  This  fact  is  im- 
portant to  bear  in  mind  in  operations  for  stretching  the  great 
sciatic  nerve,  for  the  relief  of  sciatica  or  other  affections  of  the 
nerve  or  its  branches.  The  buttock  is  convex  towards  its  inner 
part,  and  in  health  presents  on  its  outer  side  a  hollow  behind 
the  great  trochanter,  which  usually  becomes  lost  in  hip-joint 
disease.  The  back  of  the  thigh  is  convex,  and,  towards  its  lower 
part,  it  presents  a  flattening,  corresponding  to  the  lozenge-shaped 
hollow  of  the  popliteal  space,  so  that  the  tendons  and  muscles  form- 
ing its  boundaries  can  be  easily  distinguished. 

The  incision  through  the  skin  should  commence  at  the  coccyx, 
and  be  continued  in  a  semicircular  direction  along  the  crest  of  the 
ilium.  Another  incision  should  be  made  from  the  coccyx  down- 
wards and  outwards  for  about  six  inches  below  the  great  trochanter. 
In  reflecting  the  skin,  notice  the  thick  cushion  which  the  sub- 
cutaneous adipose  tissue  forms  over  the  tuberosity  of  the  ischium, 
and  the  peculiar  manner  in  which  the  fat  is  enclosed  in  meshes 
formed  by  dense  connective  tissue.  A  large  bursa  is  often  formed 
between  this  cushion  and  the  bone. 

CUTANEOUS  These  are  derived  from  the  following  sources : — 

NERVES.  Branches  from  the  posterior  divisions  of  the  first 

and  second  lumbar  nerves  descend  over  the  crest  of  the  ilium,  near 
the  origin  of  the  erector  spinge,  to  supply  the  skin  over  the  gluteus 
maximus  as  far  as  the  great  trochanter  (fig.  84,  p.  369). 

Branches  from  the  posterior  branches  of  the  three  upper  sacral 
nerves  pass  downwards  and  outwards  to  supply  for  a  short  dis- 
tance the  integument  over  the  sacrum  and  coccyx. 

The  lateral  branch  of  the  twelfth  dorsal  nerve  descends  vertically 
over  the  crest  of  the  ilium,  near  to  its  anterior  part,  and  supplies 
the  integument  of  the  front  of  the  gluteal  region. 

The  iliac  branch  of  the  ilio-hypogastric  nerve  passes  over  the 
crest  of  the  ilium,  between  the  posterior  branches  of  the  lumbar 
nerves  and  the  preceding  nerve,  and  supplies  for  a  short  distance 
the  skin  of  the  buttock. 

The  external  cutaneous  nerve  distributes   cutaneous  branches 


GLUTEUS    MAXIMUS.  655 

to  the  lower  and  outer  part  of  the  buttock  over  the  great  tro- 
chanter. 

Cutaneous  branches  from  the  lesser  sciatic  nerve  proceed  upwards 
from  beneath  the  lower  border  of  the  gluteus  maximus  to  supply 
the  skin  over  the  lower  part  of  this  muscle. 

GLUTEAL  Three   powerful   muscles   are    situated   in   the 

MUSCLES.  region  of  the  buttock,  one  above  the  other,  named, 

according  to  their  size,  the  gluteus  maximus,  medius,  and  minimus. 
The  fascia  covering  the  gluteus  maximus  is  comparatively  thinr 
posteriorly,  where  it  is  attached  to  the  sacrum,  coccyx,  and  ilium  ; 
but  anteriorly  it  is  very  dense  and  glistening,  and  gives  origin 
to  the  fibres  of  the  gluteus  medius,  and  lower  down  becomes 
continuous  with  the  fascia  lata. 

GLUTEUS  This  is  the  largest  muscle  of  the  body,  and  is 

MAXIMUS.  covered  by  a  fascia,   which    sends    prolongations 

inwards  deeply  between  the  muscular  bundles.  Its  great  size 
is  characteristic  of  man,  in  reference  to  his  erect  position.  Its 
texture  is  thick  and  coarse.  It  arises  from  the  posterior  fifth  of 
the  crest  of  the  ilium,  and  from  the  rough  surface  below  it,  from 
the  lower  part  of  the  sacrum,  the  coccyx,  and  the  great  sacro- 
sciatic  ligament.  The  fibres  descend  obliquely  forwards,  and  are 
inserted  thus  : — The  anterior  two-thirds  terminate  on  a  strong 
broad  aponeurosis  which  plays  over  the  great  trochanter,  and  joins 
the  fascia  lata  on  the  outside  of  the  thigh  (p.  616)  ;  the  remaining 
third  is  inserted  into  the  femur,  along  the  gluteal  ridge  leading 
from  the  linea  aspera  to  the  base  of  the  great  trochanter. 

This  muscle  extends  the  thigh-bone  upon  the  pelvis,  and  is 
therefore  one  of  those  most  concerned  in  raising  the  body  from 
the  sitting  to  the  erect  position,  and  in  maintaining  it  erect.  It 
propels  the  body  in  walking,  running,  or  leaping,  and  rotates  the 
thigh  outwards.  It  is  supplied  with  blood  by  the  gluteal  and 
sciatic  arteries ;  with  nerves  from  the  lesser  sciatic,  and  the 
sacral  plexus. 

w    ,  The  gluteus  maximus  should  be  reflected  from 

\Y  HAT  IS 

SEEN  BENEATH  its  origin.     The  best  way  is  to  begin  at  the  front 

THE  GLUTEUS  border,  which  overlaps  the  gluteus  medius.     The 

MAXIMUS.  dissection  is  difficult,  and  he  who  undertakes  it 


*656  GLUTEI   MUSCLES. 

for  the  first  time  is  almost  sure  to  injure  the  subjacent  parts. 
The  numerous  vessels  which  enter  its  under  surface  must  be 
•divided  before  the  muscle  can  be  reflected.  This  having  been 
accomplished,  the  following  objects  will  be  exposed : — 

The  muscle  covering  the  ilium  is  the  gluteus  medius.  At  the 
posterior  border  of  this  are  the  several  objects  which  emerge  from 
the  pelvis  through  the  great  sciatic  notch — namely,  the  pyriformis 
muscle,  above  which  is  the  trunk  of  the  gluteal  vessels  and  nerve, 
and  below  which  are  the  greater  and  lesser  sciatic  nerves,  the 
arteria  comes  nervi  ischiatici,  the  long  pudendal  nerve,  the  sciatic 
vessels,  the  pudic  vessels  and  nerve,  the  nerve  to  the  obturator 
internus,  and  the  coccygeus.  Coming  through  the  lesser  sciatic 
notch,  is  the  tendon  of  the  obturator  internus,  and  attached  to 
it  are  the  gemelli  muscles,  one  above,  the  other  below  it.  Ex- 
tending from  the  tuber  ischii  transversely  outwards  to  the  great 
trochanter  is  the  quadratus  femoris,  and,  below  this,  is  seen  the 
upper  part  of  the  adductor  magnus.  The  origins  of  the  semi-mem- 
branosus,  biceps,  semi-tendinosus,"  and  of  the  adductor  magnus, 
from  the  tuber  ischii,  are  also  seen ;  as  well  'as  the  great  sacro- 
sciatic  ligament,  which  passes  upwards  to  the  sacrum,  and  is 
pierced  by  the  coccygeal  branch  of  the  sciatic  artery.  The  great 
trochanter  is  exposed,  together  with  a  small  portion  of  the  vastus 
externus;  and  where  the  tendon  of  the  gluteus  maximus  plays 
over  the  trochanter  major,  there  is  a  large  bursa,  simple  or  multi- 
locular.  Lastly,  the  side  of  the  sacrum,  the  coccyx,  part  of  the 
crest  of  the  ilium,  the  tuberosity  of  the  ischium,  are  brought 
into  view. 

GLUTEUS  This   muscle,    covered   behind   by  the  gluteus 

MEDIUS.  maximus,  and  in  front  by  the  fascia  lata,  arises 

from  the  surface  of  the  ilium,  between  the  crest  and  the  upper 
curved  line ;  also  from  the  strong  fascia  which  covers  it  towards 
the  front.  The  fibres  converge  to  a  tendon,  which  is  inserted  into 
the  oblique  line  on  the  upper  and  outer  surface  of  the  great  tro- 
chanter :  some  of  the  anterior  fibres — in  immediate  connection 
with  the  tensor  fascise — terminate  on  the  aponeurosis  of  the  thigh. 
Between  its  insertion  and  the  bone  is  a  bursa. 

Reflect  the  gluteus  medius  to  see  the  third  gluteal  muscle. 


GLUTEAL   VESSELS   AND   NERVES.  657 

The  line  of  separation  between  them  is  marked  by  a  large  branch 
of  the  gluteal  artery. 

GLUTEUS  This  muscle  arises  from  the  surface  of  the  ilium 

MINIMUS.  below  the  upper  and  lower  curved  lines,  and  as 

far  back  as  the  margin  of  the  great  sacro-sciatic  notch.  Its  fibres 
pass  over  the  capsule  of  the  hip-joint,  and  converge  to  a  tendon 
which  is  inserted  into  a  depression  on  the  front  part  of  the  great 
trochanter,  a  bursa  being  interposed.  This  muscle  and  the  pre- 
ceding are  supplied  by  the  superior  gluteal  nerve,  a  branch  of  the 
lumbo-sacral  cord.  The  chief  action  of  this  and  the  preceding 
muscle  is  to  assist  in  balancing  the  pelvis  steadily  on  the  thigh,  as 
when  we  are  standing  on  one  leg ;  with  the  fixed  point  at  the 
ilium,  they  are  abductors  of  the  thigh.  The  anterior  fibres  of  the 
gluteus  medius  co-operate  with  the  gluteus  minimus  and  the  tensor 
fasciae  in  rotating  the  thigh  inwards. 

GLUTEAL  The  gluteal  artery  is  the  largest  branch  of  the  in- 

VESSELS  AND  ternal  iliac  (p.  540).     Emerging  from  the  pelvis 

NERVES.  through  the  great    sciatic   foramen   between  the 

pyriforrnis  and  the  gluteus  medius,  it  divides  into  two  large  branches 
for  the  supply  of  the  gluteal  muscles.  Of  these,  the  superficial 
proceeds  forwards  between  the  gluteus  maximus  and  medius,  both 
of  which  they  supply,  and  eventually  anastomose  with  the  poste- 
rior sacral  and  sciatic  arteries  ;  the  other — the  deep—  after  a  short 
course,  divides  into  two  branches  :  one — the  superior — curves  for- 
wards along  the  origin  of  the  gluteus  minimus,  towards  the  anterior 
part  of  the  ilium,  to  anastomose  with  the  ascending  branches  of  the 
external  circumflex  and  the  circumflex  iliac  arteries ;  the  other — 
the  inferior  branch — crosses  obliquely  over  the  gluteus  minimus 
towards  the  insertion  of  this  muscle,  and  anastomoses  with  the 
external  and  internal  circumflex  arteries. 

The  nerve  which  accompanies  the  gluteal  artery  is  the  superior 
gluteal  nerve,  a  branch  of  the  lumbo-sacral  cord.  It  passes  out 
above  the  pyriformis,  and  divides  into  two  branches — a  superior 
and  an  inferior  branch  ;  the  superior  branch  accompanies  the  corre- 
sponding branch  of  the  gluteal  artery,  and  supplies  the  gluteus 
medius  and  minimus  ;  the  inferior  branch  accompanies  the  inferior 
branch  of  the  gluteal  artery,  and  distributes  filaments  to  the  gluteus 

U  U 


658          EXTERNAL  ROTATORS  OF  THE  THIGH. 

medius  and  minimus,  and  the  tensor  fasciee  femoris.  In  some  sub- 
jects it  sends  a  branch  to  the  gluteus  maximus  ;  but  this  muscle  is 
chiefly  supplied  by  the  lesser  sciatic  nerve. 

A  surgeon  ought  to  be  able  to  cut  down  and  tie  the  gluteal 
artery  as  it  emerges  from  the  pelvis.  The  following  is  the  best 
rule  1  for  finding  it : — 

Draw  a  line  from  the  posterior  superior  spine  of  the  ilium  to 
the  trochanter  major,  rotated  inwards.  The  junction  of  the  upper 
with  the  middle  third  of  this  line  lies  over  the  artery  as  it  emerges 
from  the  upper  border  of  the  great  sciatic  notch. 

Now  examine  the  series  of  muscles  which  rotate  the  thigh  out- 
wards— namely,  the  pyriformis,  the  obturator  internus,  the  gemelli, 
the  quadratus  femoris,  and  the  obturator  externus. 

This  muscle  lies  immediately  below  and  parallel 
with  the  lower  fibres  of  the  gluteus  medius.  It  arises 
within  the  pelvis  by  three  fleshy  fasciculi  from  the  second,  third, 
and  fourth  segments  of  the  front  surface  of  the  sacrum  between  the 
foramina  for  the  sacral  nerves,  from  the  margin  of  the  great  sacro- 
sciatic  notch,  and  from  the  great  sacro-sciatic  ligament.  The 
fibres,  passing  horizontally  outwards,  converge  to  a  tendon,  which 
is  inserted  into  the  upper  border  of  the  great  trochanter.  Its  nerve 
comes  from  the  sacral  plexus.  Its  action  is  that  of  an  abductor 
and  an  external  rotator  of  the  femur  ;  and,  if  the  femur  be  the  fixed 
point,  it  steadies  the  pelvis  on  the  femur,  and  when  the  pelvis  has 
been  drawn  backwards  it  will  bring  it  forwards. 

OBTUBATOR  This  muscle,  of  which  little  more  than  the  ten- 

INTERNUS.  don  can  be  seen  at  present,  arises  within  the  cavity 

of  the  pelvis,  from  the  inner  surface  of  the  ischium,  bounded  pos- 
teriorly by  the  margin  of  the  great  sacro-sciatic  notch  and  the 
articular  surface  for  the  sacrum,  and  superiorly  by  the  brim  of  the 
true  pelvis ;  from  the  obturator  membrane,  and  the  obturator 
fascia ;  in  front,  from  the  inner  surface  of  the  descending  ramus  of 
the  os  pubis  and  the  ascending  ramus  of  the  ischium.  The  fibres 
are  directed  backwards  and  outwards,  and  terminate  on  four  tendons 
which  converge  towards  the  lesser  sacro-sciatic  notch  ;  pass  through 

1  The  operation  of  tying  the  gluteal  artery  was  first  performed  by  John  Bell. 
See  his  Principles  of  Surgery,  vol.  i.  p.  421. 


EXTERNAL  ROTATORS  OF  THE  THIGH.  659 

the  foramen  of  the  same  name  at  nearly  right  angles,  as  round  a 
pulley,  and  then  unite  into  a  single  tendon  to  be  inserted  into  the 
top  of  the  great  trochanter,  in  front  of  the  pyriformis.  Divide  the 
tendon  about  three  inches  from  its  insertion,  to  see  the  four  tendons 
which  play  over  the  smooth  cartilaginous  surface  on  the  inner  side  of 
the  tuberosity  of  the  ischium.  There  is  a  large  synovial  bursa  to 
diminish  friction.  The  nerve  to  this  muscle  comes  from  the  sacral 
plexus  (sometimes  from  the  pudic)  within .  the  pelvis  ;  it  emerges 
from  the  great  sacro-sciatic  foramen,  winds  round  the  spine  of  the 
ischium,  and  re-enters  the  pelvis  through  the  lesser  sacro-sciatic 
foramen  to  supply  the  muscle  on  its  inner  surface.  The  action  of 
this  muscle  is  to  rotate  the  femur  outwards ;  but,  in  the  sitting 
position,  it  loses  this  action,  and  becomes  an  abductor  of  the  thigh. 
Between  the  capsule  of  the  hip-joint  and  the  tendon,  a  synovial 
bursa  is  commonly  found,  which  not  infrequently  communicates  with 
the  bursa  placed  between  the  tendons  and  the  tuberosity  of  the 
ischium. 

These  small  muscles  are  accessory  to  the  obtu- 
rator internus,  and  are  situated,  one  above,  the 
other  below  it.  The  gemellus  superior,  the  smaller  of  the  two,  and 
occasionally  absent,  arises  from  the  outer  surface  of  the  spine  of  the 
ischium ;  the  gemellus  inferior  from  the  upper  and  back  part  of  the 
tuberosity  of  the  ischium.  Their  fibres,  attached  to  the  tendon  of 
the  obturator  internus,  are  inserted  with  it  into  the  upper  border  of 
the  great  trochanter.  The  nerves  to  these  muscles  come  from  the 
sacral  plexus  ;  that  to  the  superior  gemellus  from  the  lower  part  of 
the  plexus ;  that  to  the  inferior  gemellus  comes  out  through  the 
great  sacro-sciatic  foramen,  passes  beneath  the  superior  gemellus 
and  obturator  internus  to  enter  the  muscle  on  its  deep  aspect ;  this 
branch  also  distributes  a  filament  to  the  quadratus  femoris,  and 
another  to  the  hip-joint. 

QUADRATUS  This  quadrilateral  muscle  arises  from  the  ridge 

FEMOKIS.  on  the  outer  border  of  the  tuber  ischii.     Its  fibres 

run  horizontally  outwards,  and  are  inserted  into  the  back  of  the 
great  trochanter,  into  the  greater  part  of  the  linea  quadrati.  The 
lower  border  of  the  quadratus  femoris  runs  parallel  with  the  upper 
edge  of  the  adductor  magnus ;  in  fact,  it  lies  on  the  same  plane. 

v  u  'l 


660 


EXTERNAL  ROTATORS  OF  THE  THIGH. 


Between  these  muscles  is  generally  seen  a  terminal  branch  of  the 
internal  circumflex  artery.  Its  nerve,  as  previously  described, 
comes  from  the  sacral  plexus,  and  enters  its  deep  surface. 

OBTURATOR  1  °  see  this  muscle,  reflect  the  quadratus  femoris 

EXTERNUS.  from  its  origin.     It  arises  from  the  outer  surface 

of  the  body  of  the  os  pubis,  from  the  front  surface  of  the  rami  of 

FIG.  152. 


12.  N.  of  pyriformis. 

13.  N.  of  gemellus  superior. 

14.  N.  of  gemellus  inferior. 

15.  N.  of  quadratus  femoris. 

16.  N.  of  gluteus  maximus. 

17.  Long  pudendal  n. 

18.  Cutaneous  n.  of  the  but- 

tock. 

19.  N.  of  the  long  head  of 

the  biceps. 

20.  N.  of  semi-tendinosus. 

21.  N.    of    semi-membrano- 

sus. 

22.  N.  of  short  head  of  the 

biceps. 


1,  2,  3,  4,  5.  Sacral  nn. 

6.  Superior  gluteal  n. 

7.  Great  sciatic  n. 

8.  Lesser  sciatic  n. 

9.  Pudic  n. 

10.  N.  of  obturator  iuternus. 

11.  N.  of  levator  ani. 


PLAN    OF    THE    SACRAL    PLEXUS    AND    BRANCHES. 

the  os  pubis  and  ischium,  which  form  the  inner  border  of  the  ob- 
turator foramen,  from  the  inner  two-thirds  of  the  outer  surface  of 
the  obturator  membrane,  and  from  the  tendinous  arch  over  the 
obturator  vessels.  Its  fibres  converge  to  a  tendon  which  runs 
horizontally  outwards  over  a  groove  on  the  ischium,  and,  running 
across  the  back  of  the  hip-joint,  is  inserted  into  the  deepest  part  of 
the  trochanteric  fossa  of  the  femur.  Its  nerve  is  a  branch  of  the 


GREAT    SCIATIC    NERVE.  661 

posterior  division  of  the  obturator  nerve.  This  muscle  has  in  front 
of  it,  the  adductor  longus  and  brevis,  the  pectineus,  the  psoas  and 
iliacus,  the  neck  of  the  femur,  and  the  capsular  ligament ;  above  it 
are,  the  capsular  ligament  and  the  inferior  gemellus  ;  beloiv  it  are, 
the  adductor  magnus  and  quadratus  femoris  ;  behind  it  are,  the 
obturator  membrane  and  the  quadratus  femoris. 

GREAT  SCIATIC  This  large  nerve,  formed  by  the  union  of  the 

NEKVE.  last  lumbar  and  the  four  upper  sacral  nerves  (fig. 

152),  is  the  largest  nerve  in  the  body,  being  three-quarters  of  an 

FIG.  153. 


1.  Gluteus  medius.  i&MHnMM  6'  Great  s°iatic  nerve. 

2.  Pyriformis.  /JPf^HI  OK\  "'  Quadratus  femoris. 

3.  Lesser  sciatic  nerve.  3  f         •     .  '^C^^^^^Bmj  8'  Gluteus  ma*1"*1118- 

4.  Obturator  interims,  * \ f^T-J-  /'-/^f/NjiSsf'  9-  The  semitendinosus 

with  the  two  gemelli.  /  i          jjj^f.  ggf  1JF-  &nd  biceps> 

5.  Coccygeus.  U  *^     Wi.Mi^-  *  10-  Adductor  magnus. 


DEEP    MUSCLES    OF    THE    OLUTEAL    REGION. 


inch  in  breadth,  and  supplies  all  the  flexor  muscles  of  the  lower 
extremity  and  the  extensors  of  the  foot. 

Emerging  from  the  pelvis  through  the  great  sacro-sciatic 
foramen  below  the  pyriformis,  it  descends  over  the  external  rotator 
muscles  of  the  thigh,  along  the  interval  between  the  tuber  ischii 
and  the  great  trochanter,  but  rather  nearer  to  the  former  ;  so  that, 
in  the  sitting  position,  the  nerve  is  protected  from  pressure  by  this 
bony  prominence.  The  nerve  does  not  descend  quite  perpendicu- 
larly, but  rather  obliquely  forwards  upon  the  adductor  magnus, 
parallel  with  the  great  sacro-sciatic  ligament,  and  below  the  middle 
of  the  thigh  divides  into  the  internal  popliteal  and  the  peroneal  (or 


662  SCIATIC  NERVES  AND  AETERY. 

external  popliteal).  It  is  accompanied  by  a  branch  of  the  sciatic 
artery,  called  the  comes  nervi  ischiatici.1  The  nerve  distributes 
branches  to  the  hamstring  muscles  and  the  adductor  magnus,  and 
sends  two  or  more  small  branches  to  the  hip-joint  which  pierce  the 
posterior  part  of  the  capsular  ligament. 

SMALL  SCIATIC  This  comes  from  the  lower  part  of  the  sacral 

NERVE,  plexus.     It  leaves  the  pelvis  below  the  pyriformis, 

with  the  great  sciatic  nerve,  but  on  the  inner  side  of  it,  and  in 
company  with  the  sciatic  artery.  It  descends  behind  the  gluteus 
maximus,  and  becomes  cutaneous  at  its  lower  border.  The  mus- 
cular branches  which  it  gives  off  are  one  or  more — inferior  gluteal 
— which  enter  the  under  surface  of  the  gluteus  maximus  near  its 
lower  border.  All  its  other  branches  are  cutaneous,  and  are  divided 
into  an  ascending  and  internal  group :  the  ascending  branches  turn 
round  the  lower  border  of  the  gluteus  maximus,  and  supply  the  skin 
of  the  buttock ;  the  internal  branches  supply  the  skin  on  the  inner 
and  posterior  aspect  of  the  thigh  in  its  upper  part,  and  one  branch, 
larger  than  the  rest,  called  the  inferior  pudendal,  turns  inwards  to- 
wards the  perineum  to  supply  the  skin  of  that  region  and  the  scro- 
tum, communicating  with  the  inferior  heemorrhoidal  and  superficial 
perineal  nerves.  The  continued  trunk  runs  down  the  back  of  the 
thigh  beneath  the  muscular  fascia,  as  low  as  the  upper  part  of  the 
calf  with  the  external  saphenous  vein,  supplying  the  skin  all  the 
way  down,  and  communicates  with  the  short  saphenous  nerve. 

This,  one  of  the  terminal  branches  of  the  internal 
iliac,  courses  along  the  inner  aspect  of  the  sacral 
plexus  and  pyriformis,  behind  the  pudic  artery,  while  this  vessel 
is  still  within  the  pelvis.  It  emerges  from  the  pelvis  between  the 
pyriformis  and  coccygeus,  and  is  then  seen  in  the  gluteal  region 
coming  out  between  the  pyriformis  and  superior  gemellus.  It  then 
descends  between  the  tuber  ischii  and  the  great  trochanter,  along 
the  inner  side  of  the  great  sciatic  nerve.  It  gives  off: — (1)  within 

1  The  arteria  comes  nervi  ischiatici  runs  generally  by  the  side  of  the  nerve,  but 
sometimes  in  the  centre  of  it.  This  artery  becomes  one  of  the  chief  channels  by 
which  the  blood  reaches  the  lower  limb  after  ligature  of  the  femoral.  See  in  the 
Museum  of  the  Boyal  College  of  Surgeons  a  preparation  in  which  the  femoral  was 
tied  by  John  Hunter  fifty  years  before  the  man's  death. 


PUDIC  ARTERY  AND  NERVE. 


663 


the  pelvis,  branches  to  the  muscles  which  form  the  muscular  floor 
of  the  pelvis,  to  the  rectum,  the  bladder,  prostate  and  vesiculee 
seminales  ;  (2)  external  to  the  pelvis,  it  gives  off:  a,  a  coccygeal 
branch,  which  runs  inwards  through  the  great  sacro-sciatic  liga- 
ment, then  ramifies  in  the  gluteus  maximus,  and  on  the  back  of 
the  coccyx  ;  b,  the  comes  nervi  ischiatici,  which  accompanies  the 
great  sciatic  nerve  for  a  short  distance,  and  then  enters  its  sub- 
stance ;  c,  the  inferior  gluteal  branches,  which  enter  the  gluteus 

FIG.  154. 


1.  Gluteal  artery 

and  nerve. 

2.  Pudic     artery 

and  nerve,  and 
nerve  to  obtu- 
rator interims. 


3.  Great  sacro-sci- 

atic nerve. 

4.  Sciatic  artery. 

5.  Internal  circum- 

flex artery. 

C.  The  first  perfo- 
rating artery. 


THE  ARTERIES  OF  THE  GLUTEAL  REGION. 


maximus  ;  d,  articular  branches,  which  pierce  the  posterior  capsule 
of  the  hip-joint ;  e,  muscular  branches  to  the  several  external 
rotators  and  the  hamstring  muscles,  and  which  inosculate  with 
the  external  and  internal  circumflex,  gluteal,  obturator,  and  first 
perforating  arteries. 

PUDIC  ABTERT  The  course  of  this  artery  and  nerve  has  been 

AND  NERVE.  fully  described  (p.  542).     Observe  now  that  they 

pass  over  the  spine  of  the  ischium,  accompanied  by  the  nerve  to  the 
obturator  internus,  and  that  in  a  thin  subject  it  is  possible  to  com- 
press the  artery  against  the  spine.  The  rule  for  finding  it  is  this  : 


664  POPLITEAL   SPACE. 

rotate  the  foot  inwards,  and  draw  a  line  from  the  top  of  the  great 
trochanter  to  the  base  of  the  coccyx  ;  the  junction  of  the  inner  with 
the  outer  two-thirds  gives  the  situation  of  the  artery.1 

POPLITEAL  I*  ig  advisable  to  examine  the  popliteal  space  at 

SPACE  :  ITS  this  stage  of  the  dissection,  in  order  that  the  various 

BOUNDARIES.  parts  may  be  carefully  made  out  with  as  little  dis- 

turbance as  possible  of  their  mutual  relations. 

SUBFACE  The  popliteal  space  is  a  lozenge-shaped  hollow 

MARKING.  at  the  back  of  the  knee-joint,  extending  as  high  as 

the  junction  of  the  middle  with  the  lower  third  of  the  femur,  and 
as  low  as  the  upper  sixth  of  the  tibia.  The  hollow  is  most  apparent 
when  the  knee  is  flexed,  as  then  the  tendinous  boundaries  stand  out 
in  bold  relief;  it  is  almost  lost  when  the  leg  is  extended.  The 
tendon  on  the  outer  side  is  that  of  the  biceps,  diverging  to  the  head 
of  the  fibula  ;  on  the  outer  side,  and  below,  are  the  plantaris  and 
outer  head  of  the  gastrocnemius,  which  are  not  well  defined ;  on 
the  inner  side,  above,  we  can  feel  three  tendons  in  the  following 
order  from  within  outwards — the  semitendinosus,  the  semimem- 
branosus,  and  the  gracilis ;  below,  on  their  inner  side,  is  the  inner 
head  of  the  gastrocnemius.  The  upper  angle  of  this  space  is  formed 
by  the  diverging  biceps  and  semitendinosus  ;  the  lower  angle  by 
the  converging  heads  of  the  gastrocnemius.  Passing  from  above 
downwards  in  the  middle  of  the  space,  and  in  the  following  order, 
are  the  internal  popliteal  nerve,  the  popliteal  vein  and  artery ;  and 
along  the  inner  border  of  the  biceps  can  be  felt  the  external  popli- 
teal nerve.  Filling  up  the  hollow  is  a  quantity  of  soft  fat,  with 
some  lymphatic  glands,  and  on  the  bone  rest  the  articular  arteries. 
A  vertical  incision  must  be  made  along  the 
middle  of  the  ham,  extending  from  six  inches 
above,  to  three  inches  below  the  knee  :  transverse  incisions  should 
be  made  at  each  extremity  of  the  vertical,  so  that  the  skin  may  be 
conveniently  reflected.  In  doing  so,  care  must  be  taken  to  preserve 
the  cutaneous  branch  of  the  lesser  sciatic  nerve,  which  descends 
over  the  space  to  the  back  of  the  leg. 

1  Mr.  Travers  succeeded  in  arresting  haemorrhage  from  a  sloughing  ulcer  of 
the  glans  penis  by  pressing  the  pudic  artery  with  a  cork  against  the  spine  of  the 
ischium. 


POPLITEAL   SPACE.  665 

The  muscular  fascia  covering  the  space  is  very  strong,  and 
strengthened  by  numerous  transverse  fibres.  It  is  pierced  by  the 
posterior  saphena  vein,  which  passes  in  to  join  the  popliteal  vein. 

The  fascia  having  been  reflected,  the  muscles  and  tendons  con- 
stituting the  boundaries  of  the  popliteal  space  are  to  be  cleaned. 
The  boundaries  of  the  space  can  now  be  seen  to  be  formed,  as  before 
stated,  above,  by  the  divergence  of  the  hamstring  muscles  to  reach 
their  respective  insertions  ;  below,  by  the  converging  heads  of  the 
gastrocnemius :  its  shape  is  therefore  that  of  a  lozenge.  Above, 
it  is  bounded  on  the  inner  side  by  the  semitendinosus,  semimem- 
branosus,  gracilis,  and  sartorius  ;  on  the  outer  side,  by  the  biceps ; 
below,  it  is  bounded,  on  the  inner  side  by  the  internal  head  of  the 
gastrocnemius  ;  on  the  outer,  by  the  external  head  of  this  muscle 
and  the  plantaris. 

The  space  is  occupied  by  a  quantity  of  fat,  which  permits  the 
easy  flexion  of  the  knee ;  and  in  this  fat  ate  found  the  popliteal 
vessels  and  nerves,  in  the  following  order  : — nearest  to  the  surface 
are  the  nerves  ;  the  artery  lies  close  to  the  bone,  the  vein  being 
superficial  to  the  artery  (fig.  155). 

GKEAT  SCIATIC  Along  the  outer  border  of  the  semimembranosus, 

NERVE.  and  covered  by  the  long  head  of  the  biceps,  is  the 

great  sciatic  nerve,  which,  after  giving  off  branches  to  the  three 
great  flexor  muscles  and  the  adductor  magnus,  divides,  about  the 
lower  third  of  the  thigh  (higher  or  lower  in  different  subjects),  into 
two  large  nerves — the  peroneal  or  external  popliteal  and  the  internal 
popliteal. 

The  peroneal  nerve  runs  close  by  the  inner  side  of  the  tendon 
of  the  biceps,1  and  subsequently  in  the  groove  between  this  muscle 
and  the  outer  head  of  the  gastrocnemius,  towards  the  head  of  the 
fibula.  As  it  passes  round  the  joint  it  gives  off  two  articular 
branches  to  the  outer  side  of  the  knee,  which  accompany  the 
external  superior  and  inferior  articular  arteries,  and  a  recurrent 
articular  branch,  which  runs  with  the  recurrent  tibial  artery  to  the 
front  of  the  knee.  It  supplies  also  two  or  three  cutaneous  brandies 

1  The  nerve  is,  therefore,  very  liable  to  be  injured  in  the  operation  of  dividing 
the  outer  hamstring.  In  the  diagram,  the  nerve  is  not  near  enough  to  the  tendon, 
their  connections  having  been  severed. 


666 


POPLITEAL   SPACE. 


to  the  posterior  and  outer  surfaces  of  the  leg,  as  far  as  its  middle 
third. 

The  communicans  peronei  (fig.  155)  is  a  small  branch  given  off 
as  the  nerve  passes  over  the  gastrocnemius  ;  it  crosses  the  outer 
head  of  this  muscle  and  joins  the  external  saphenous,  which  runs 

Fio.  155. 


Semitendinosus. 

Semimembranosus. 
Gracilis. 

Sartorius. 


Inner  haid  of  gastrocne- 
mius. 


LEFT    POPLITEAL    SPACE. 


down  the  back  of  the  calf,  and  behind  the  external  malleolus,  to 
supply  the  outer  side  of  the  foot  and  little  toe. 

Below  the  head  of  the  fibula  we  have  already  traced  the  division 
of  the  peroneal  into  the  anterior  tibial,  and  the  musculo-cutaneous 
nerves  (p.  652). 

The  internal  popliteal  nerve,  the  larger  of  the  two  divisions  of 
the  great  sciatic  nerve,  accompanies  the  popliteal  artery,  and,  at  the 


POPLITEAL   SPACE.  667 

lower  border  of  the  popliteus,  it  is  continued  under  the  name  of  the 
posterior  tibial.  The  nerve  in  the  popliteal  space  lies  superficial  to 
and  rather  external  to  the  artery,  and  gives  off  four  or  five  muscular 
branches  which  supply  the  two  heads  of  the  gastrocnemius,  the  plan- 
taris, the  soleus,  and  the  popliteus  ;  three  articular  branches,  two 
accompanying  the  internal  superior  and  inferior  articular  arteries, 
the  third  piercing  the  back  of  the  capsule  accompanied  by  the  azygos 
artery  ;  and  the  short  or  external  saphenous,  which  descends  in  the 
groove  between  the  two  heads  of  the  gastrocnemius,  is  joined  about 
the  middle  of  the  leg  by  the  communicans  peronei,  and  then,  run- 
ning down  behind  the  outer  malleolus  in  company  with  the  external 
saphena  vein,  is  distributed  to  the  outer  side  of  the  foot  and  the 
little  toe.  The  continuation  of  the  internal  popliteal  nerve,  as 
posterior  tibial,  supplies  all  the  flexor  muscles  on  the  back  of  the 
leg  and  the  sole  of  the  foot. 

POPLITEAL  By  clearing  out  all  the  fat,  we  observe  that  the 

VESSELS.  popliteal  vessels  enter  the  ham  through  an  aperture 

in  the  adductor  magnus,  and  descend  close  to  the  back  part  of  the 
femur,  and  the  back  of  the  knee-joint.  At  first  they  are  partially 
overlapped  (in  muscular  subjects)  by  the  semimembranosus  ;  in- 
deed the  outer  border  of  this  muscle  is  a  good  guide  to  the  artery 
in  the  operation  of  tying  it.  The  popliteal  artery  lies  upon  the  tri- 
angular surface  at  the  back  of  the  lower  third  of  the  femur  ;  then, 
upon  the  ligamentum  posticum  Winslowii ;  and,  lastly,  upon  the 
popliteus,  at  the  lower  border  of  which  it  divides  into  the  anterior 
and  posterior  tibial. 

Superficial  to  the  artery  are  the  semimembranosus,  a  consider- 
able amount  of  fat,  the  gastrocnemius,  the  plantaris,  the  soleus, 
the  popliteal  vein,  and  the  internal  popliteal  nerve  ;  internally.,  it  has 
the  semimembranosus,  the  internal  condyle  of  the  femur,  and  the 
inner  head  of  the  gastrocnemius  ;  externally,  it  has  the  biceps,  the 
external  condyle,  the  outer  head  of  the  gastrocnemius,  and  the 
plantaris. 

The  artery  gives  off  the  external  and  internal  superior  articular 
arteries ;  lower  down,  the  external  and  internal  inferior  articular 
arteries,  the  superior  and  inferior  muscular  branches,  the  azygos,  and 
cutaneous  branches.  The  description  of  these  branches  of  the 


668  DISSECTION    OF  THE   BACK   OF   THE   THIGH. 

popliteal  will  deferred  till  later,  until  the  muscles  of  the  calf  have 
been  reflected. 

The  articular  branches  which  come  from  the  popliteal  are  given 
off  at  right  angles  to  that  vessel ;  and  besides  these  it  gives  off  the 
sural  which  supply  the  muscles  of  the  calf,  and  the  azygos  artery  ; 
close  to  the  vessel  is  the  articular  branch  of  the  obturator  nerve 
which  supplies  the  knee-joint. 

The  popliteal  vein  lies  superficial  to  the  artery,  and  rather  to 
its  outer  side.  It  receives  the  short  saphena  vein.  Its  coats  are 
remarkably  thick,  and  on  transverse  section  resemble  those  of  an 
artery  of  a  similar  size. 

LYMPHATIC  Two  or  more  lymphatic  glands  are  situated  one 

GLANDS.  on  each  side  of  the  artery.     They  deserve  atten- 

tion, because,  when  enlarged,  their  close  proximity  to  the  artery 
may  communicate  a  pulsation  which  might  be  mistaken  for  an 
aneurism. 


DISSECTION   OF   THE   BACK  OF   THE   THIGH. 

The  incision    should  be    continued  along    the 

remainder  of  the  back  of  the  thigh,  and  the  skin 

reflected.     The  fat  should  be  removed,  and  the  cutaneous  branches 

derived  from  the  external  and  internal  cutaneous  nerves,  and  the 

small  sciatic,  should  be  carefully  sought  out. 

CUTANEOUS  ^ ^e  s^^n  on  ^ne  middle  of  the  back  of  the  thigh 

NERVES  AND  is  supplied  by  the  small  sciatic  nerve,  which  runs 

VEINS,  down  beneath  the  deep  fascia  as  far  as  the  middle 

third  ;  then  pierces  it,  and  runs  down  as  far  as  the  middle  third 
of  the  calf,  distributing  branches  on  each  side.  On  the  outer 
side,  a  few  cutaneous  branches  from  the  posterior  division  of  the 
external  cutaneous  nerve  supply  the  skin  as  far  as  the  middle  third  ; 
on  the  inner  side  are  small  branches  from  the  small  sciatic  and  the 
internal  cutaneous  nerves  as  low  as  the  knee-joint. 

The  subcutaneous  veins  at  the  back  of  the  thigh  are  very  small ; 
here  they  would  be  liable  to  pressure.  But  near  the  popliteal  space 
there  is  a  vein,  called  the  external  or  short  sapliena.  It  comes  up 


BACK   OF   THE   THIGH.  669 

the  back  of  the  calf,  and  joins  the  popliteal  vein  after  perforating 
the  strong  fascia  covering  the  space. 

MUSCULAR  Respecting    this,    remark   that   its    fibres    run 

FASCIA.  chiefly  in  a  transverse  direction,  that  it  becomes 

stronger  as  it  passes  over  the  popliteal  space,  and  that  here  it  is 
connected  with  the  tendons  on  either  side.  Remove  it,  to  examine 
the  powerful  muscles  which  bend  the  leg,  called  the  hamstrings. 

HAMSTKING  There  are  three  of  these,  and  all  arise  by  strong 

MUSCLES.  tendons  from  the  tuber  ischii.     One,  the  biceps, 

passes  downwards  and  outwards  to  be  inserted  into  the  head  of 
the  fibula ;  the  other  two — namely,  the  semitendinosus  and  semi- 
membranosus — descend  inwards  and  are  inserted  into  the  tibia. 
The  divergence  of  these  muscles  towards  their  respective  inser- 
tions occasions  the  space  termed  the  popliteal,  which  is  occupied  by 
soft  fat,  the  popliteal  vessels,  nerves,  and  lymphatic  glands. 

This  muscle  has  two  origins,  a  long  and  a  short. 
The  long  head  arises,  by  a  strong  tendon,  from 
the  back  part  of  the  tuber  ischii  in  common  with  the  semitendino- 
sus ;  the  short  head,  by  fleshy  fibres,  from  the  outer  lip  of  the  linea 
aspera  of  the  femur  between  the  vastus  externus  and  the  adductor 
magnus,  and  from  the  external  intermuscular  septum  :  this  origin 
begins  at  the  linea  aspera,  just  below  the  insertion  of  the  gluteus 
maximus,  and  continues  nearly  down  to  the  external  condyle.  It 
joins  the  long  head  of  the  muscle,  and  both  terminate  on  a  common 
tendon,  which  is  inserted  into  the  outer  side  of  the  head  of  the 
fibula,  by  two  portions  separated  by  the  external  lateral  ligament 
of  the  knee-joint.  It  also  gives  off  a  strong  expansion  to  the  fascia 
of  the  leg.  The  tendon  covers  part  of  the  external  lateral  ligament 
of  the  knee-joint,  and  a  small  bursa  intervenes. 

The  biceps  is  not  only  a  flexor  of  the  leg,  but  rotates  the  leg, 
when  bent,  outwards.  It  is  the  muscle  which  in  chronic  disease  of 
the  knee  dislocates  the  leg  outwards  and  backwards,  and  at  the 
same  time  rotates  it  outwards.  Each  head  of  the  biceps  is  supplied 
by  the  great  sciatic  nerve.  The  short  head  is  sometimes  supplied 
by  the  peroneal. 

SEMITEN-  This  arises,  in  common  with  the  biceps,  from 

DINOSUS.  the   back   part    of  the  tuber  ischii  by  muscular 


670  HAMSTRING   MUSCLES. 

fibres  and  also  from  the  inner  border  of  the  tendon  of  the  biceps 
for  about  three  inches.  The  muscle  passes  downwards  and  inwards, 
and  terminates  in  the  middle  of  the  thigh  in  a  long  round  tendon, 
which  rests  upon  the  semimembranosus,  and  is  inserted  into  the 
upper  part  of  the  inner  surface  of  the  tibia  by  an  expanded  tendon, 
below  the  tendon  of  the  gracilis,  and  behind  that  of  the  sartorius. 
Like  them,  it  plays  over  the  internal  lateral  ligament  of  the  knee, 
and  is  provided  with  a  bursa.  Its  nerve  comes  from  the  great 
sciatic. 

The  semitendinosus  sends  off  from  the  lower  border  of  its  tendoo 
a  very  strong  fascia  to  cover  the  leg,  which  is  attached  along 
the  inner  edge  of  the  tibia.  The  middle  of  the  muscle  is  usually 
intersected  by  an  oblique  tendinous  line. 

SEMIMEM-  This  muscle  arises  from  the  upper  and  outer 

BKANOSUS.  facet  on  the  back  of  the  tuber  ischii  above  and 

external  to  the  two  preceding,  by  means  of  a  strong  flat  tendon, 
which  extends  nearly  half-way  down  the  thigh.  This  tendon  de- 
scends obliquely  under  the  biceps  and  semitendinosus,  and  termi- 
nates in  a  bulky  muscle,  which  lies  on  a  deeper  plane,  and  more 
internal  than  the  others,  and  is  inserted  by  a  thick  tendon  into  the 
posterior  and  inner  part  of  the  internal  tuberosity  of  the  head  of 
the  tibia.  In  connection  with  the  insertion  of  this  tendon,  notice, 
(1)  that  from  its  inner  side  a  strong  fasciculus  is  prolonged  forwards 
under  the  internal  lateral  ligament  of  the  knee,  and  that  a  bursa 
intervenes  between  them  ;  (2)  that  from  its  outer  and  posterior  part 
it  sends  a  strong  prolongation  upwards  and  outwards  to  the  back 
part  of  the  external  condyle  of  the  femur,  forming  the  principal 
portion  of  the  ligamentwn  posticum  Winslowii,  which  covers  the 
back  of  the  knee-joint ;  (3)  that  a  dense  fascia  proceeds  from  its 
lower  border,  and  binds  down  the  popliteus ;  (4)  that  it  is  intimately 
connected  with  the  semilunar  cartilages  of  the  joint,  so  as  to  keep 
them  in  place  during  its  movements.  Its  nerve  comes  from  the 
great  sciatic. 

A  great  bursa  is  almost  invariably  found  between  the  semi- 
membranosus and  the  inner  head  of  the  gastrocnemius,  where  they 
rub  one  against  the  other.  It  is  generally  from  one  and  a  half  to 
two  inches  long.  The  chief  point  of  interest  concerning  it  is,  that 


HAMSTRING   MUSCLES. 


671 


FIG.  156. 


it  occasionally  communicates  with  the  synovial  membrane  of  the 
knee-joint,  not  directly,  but  through  the  medium  of  another  bursa 
beneath  the  inner  head  of  the  gastrocnemius.  From  an  examina- 
tion of  150  bodies,  it  appears  that  this  communication  exists  about 
once  in  five  times  ;  and  it  need  scarcely  be  said  that  the  proportion 
is  large  enough  to  make  us  cautious  in  in- 
terfering  with  this  bursa  when  it  becomes 
enlarged.1 

ACTION  OF  THE           These  muscles  produce 
HAMSTRING  two  different  effects,  ac- 

MUSCLES.  cording    as    their    fixed 

point  is  at  the  pelvis  or  the  knee.  With 
the  fixed  point  at  the  pelvis,  they  bend 
the  knee;  with  the  fixed  point  at  the 
knee,  they  take  a  very  important  part  in 
maintaining  the  body  erect.  For  instance, 
if,  when  standing,  the  body  be  bent  at  the 
hip,  and  the  muscles  in  question  be  felt, 
it  will  be  found  that  they  are  in  strong 
action,  to  prevent  the  trunk  from  falling 
forwards :  they,  too,  are  the  chief  agents 
concerned  in  bringing  the  body  back  again 
to  the  erect  position.  In  doing  this,  they 
act  upon  a  lever  of  the  first  order,  as 
shown  in  fig.  156 ;  the  acetabulum  being 

the  fulcrum  r,  the  trunk  w,  the  weight  to  be  moved,  and  the 
power  P  at  the  tuber  ischii. 

To  put  the  action  of  the  muscles  of  the  thigh  on  the  pelvis  in 
the  clearest  point  of  view,  let  us  suppose  we  are  standing  upon 
one  leg :  the  bones  of  the  lower  extremity  represent  a  pillar  which 
supports  the  weight  of  the  trunk  on  a  ball-and-socket  joint ;  the 
weight  is  nicely  balanced  on  all  sides,  and  prevented  from  falling 

1  When  the  bursa  in  question  becomes  enlarged,  it  occasions  a  fluctuating 
swelling  of  greater  or  less  dimensions  on  the  inner  side  of  the  popliteal  space. 
The  swelling  bulges  out,  and  becomes  tense  and  elastic  when  the  knee  is  extended, 
and  vice  versa.  As  to  its  shape,  it  is  generally  oblong ;  but  this  is  subject  to 
variety,  for  we  know  that  the  bursas,  when  enlarged,  are  apt  to  become  multilocular, 
and  to  extend  between  the  muscles  where  there  is  the  least  resistance. 


672  DISSECTION   OF   THE   BACK   OF  THE   LEG. 

by  four  groups  of  muscles.  In  front,  are  the  rectus  and  sartorius  ; 
on  the  inner  side,  the  adductors ;  on  the  outer  side,  the  gluteus 
medius  and  minimus;  behind,  the  hamstrings  and  gluteus  maximus. 

When  the  knee  is  semi-flexed,  the  semimembranosus  can  also 
rotate  the  leg  inwards,  thus  assisting  the  popliteus ;  the  biceps 
can  also  in  the  same  position  of  the  knee  rotate  the  leg  slightly 
outwards. 

The  hamstring  muscles  are  supplied  with  blood  by  the  perfo- 
rating branches  of  the  profunda,  which  come  through  the  tendon 
of  the  adductor  magnus  close  to  the  femur,  and  by  muscular 
branches  from  the  popliteal  artery.  Their  nerves  are  derived  from 
the  great  sciatic. 

GREAT  SCIATIC  This  nerve   descends   from    the  gluteal  region 

NERVE.  upon    the    adductor    magnus,    and,    after   being 

crossed  by  the  long  head  of  the  biceps,  runs  along  the  outer 
border  of  the  semimembranosus  down  the  popliteal  space.  The 
great  sciatic  divides  into  its  two  terminal  divisions  at  a  variable 
distance  from  its  exit  through  the  great  sciatic  foramen,  sometimes 
high  up,  occasionally  lower  down  than  usual.  The  further  course 
of  this  nerve  has  already  been  described  (p.  665). 

Deferring  the  course,  relations,  and  branches  of  the  popliteal 
artery  till  this  vessel  is  exposed  throughout  its  whole  course,  pass 
on  now  to  the  dissection  of  the  calf. 


DISSECTION   OF   THE   BACK   OF   THE   LEG. 

SURFACE  The   back  of  the  leg  gradually  narrows   from 

MARKING.  above  downwards  so  as  to  form  a  long  cone ;  the 

upper  half  is  convex  and  fleshy,  corresponding  to  the  gastrocnemius 
and  the  soleus  muscles  ;  the  lower  half  suddenly  diminishes,  so  that 
the  posterior  borders  of  the  tibia  and  fibula  can  be  easily  felt 
extending  to  their  respective  malleoli.  In  a  well-developed  subject 
with  not  much  fat  the  two  heads  of  the  gastrocnemius  can  be  seen 
through  the  skin,  the  inner  head  being  the  broader  and  lower  of 
the  two ;  the  tendon  into  which  they  are  inserted  (tendo  Achillis) 
rapidly  narrows  to  be  attached  to  the  posterior  and  upper  part  of 


BACK    OF   THE    LEG.  673 

the  tuberosity  of  the  os  calcis.  On  the  inner  and  outer  sides  of  the 
lower  part  of  this  tendon  there  is  a  well-defined  vertical  groove ; 
bounded  laterally  by  the  tibia  and  fibula.  In  cases  of  synovial 
disease  of  the  ankle-joint  these  grooves  are  lost,  so  that  instead  of 
a  depression  there  is  a  convexity.  In  these  grooves  can  be  felt 
the  tendons  passing  round  the  ankle  behind  the  malleoli ;  on  the 
inner  side  are  the  tibialis  posticus,  flexor  longus  digitorum,  and 
flexor  longus  hallucis ;  on  the  outer  side  are  the  peronei  longus  and 
brevis. 

Continue  the  incision  down  the  centre  of  the  calf  to  the 
heel,  where  a  transverse  incision  must  also  be  made.  The  skin 
should  now  be  reflected,  taking  care  of  the  subcutaneous  veins  and 
nerves. 

SHORT  OR  The  large  vein  seen  in  the  middle  of  the  back 

POSTERIOR  of  the  leg  is  called  the  short  or  posterior  saphena. 

SAPHENA  VEIN  j^  commences  on  the  outer  side  of  the  dorsum  of 
the  foot,  ascends  behind  the  outer  ankle,  where  it  has  a  communi- 
cation with  the  deep  veins,  and  then  runs  up  the  calf  between 
the  two  bellies  of  the  gastrocnemius,  receiving  numerous  veins  in 
its  course,  and  being  guarded  by  several  valves.  It  eventually 
passes  through  the  muscular  fascia,  and  joins  the  popliteal  vein. 

CUTANEOUS  The  back  of  the  leg  is  supplied  by  cutaneous 

NERVES.  nerves  :  in  the  middle,  above,  by  the  small  sciatic 

nerve,  and  below,  by  the  short  or  external  saphenous ;  on  the  outer 
side,  by  the  communicans  peronei ;  and  on  the  inner  side,  by 
branches  from  the  internal  saphenous  nerve. 

SHORT  OR  The   short   scuplienous   nerve !    is    derived  from 

EXTERNAL  the  internal  popliteal  nerve  (fig.  155),  and  passes 

.SAPHENOUS  NERVE.  ,jown  beneath  the  deep  fascia  between  the  two 
heads  of  the  gastrocnemius  to  the  middle  of  the  calf,  where  it 
pierces  the  fascia.  Here  it  is  joined  by  a  branch  from  the  peroneal 
nerve  (communicans  peronei) ;  it  then  descends  with  the  short 
saphena  vein,  usually  on  its  fibular  side,  and  is  finally  distributed 
to  the  outer  side  of  the  foot  and  the  little  toe. 

1  This  nerve  is  sometimes  called  the  communicans  poplitei,  and  does  not  take 
the  name  of  short  saphenous  nerve  till  its  junction  with  the  communicans  peronei 
<p.  666). 

X  X 


674  MUSCLES   OF   THE   CALF. 

To  expose  the  muscles  of  the  calf,  reflect  the  muscular  fascia  by 
incisions  corresponding  to  those  made  through  the  skin. 

MUSCLES  OF  The  great  flexor  muscle  of  the  foot  consists  of 

THE  CALF.  two  portions :  the  superficial  one,  called  the  gas- 

trocnemius,  arises  from  the  lower  end  of  the  femur ;  the  deep  one, 
called  the  soleus,  arises  from  the  tibia  and  fibula.  They  are 
attached  to  one  thick  tendon,  called  the  tendo  Achillis,  which  is 
inserted  into  the  os  calcis. 

This  muscle  arises  by  two  strong  tendinous 
heads  from  the  back  of  the  condyles  of  the  femur 
(fig.  155).  The  inner  head  is  the  larger,  longer,  and  more  muscular,, 
and  arises  from  a  depression  at  the  upper  and  back  part  of  the 
internal  condyle,  and, .  for  a  short  distance,  by  fleshy  fibres  from 
the  line  leading  from  the  linea  aspera  to  the  internal  condyle  ;  the 
outer  head  from  the  back  and  upper  part  of  the  external  condyle 
above  the  popliteus,  and  also  from  the  line  leading  to  the  linea 
aspera.  The  two  parts  of  the  muscle  descend,  distinct  from  each 
other,  and  form  the  two  bellies  of  the  calf,  of  which  the  inner  i& 
rather  the  lower.  Both  terminate,  rather  below  the  middle  of  the 
leg,  on  the  broad  commencement  of  the  tendo  Achillis. 

The  gastrocnemius  should  be  divided  transversely  near  its 
attachment  to  the  tendo  Achillis,  and  reflected  upwards  from  the 
subjacent  soleus,  as  high  as  its  origin.  By  this  proceeding  you 
observe  that  the  contiguous  surfaces  of  the  muscles  are  covered  by 
a  glistening  tendon,  which  receives  the  insertion  of  their  fibres, 
and  transmits  their  collected  force  to  the  tendo  Achillis. 

Observe  also  the  large  sural  vessels  and  nerves  (branches  of 
the  popliteal)  which  enter  the  mesial  aspect  of  each  head  of  the 
muscle.  To  facilitate  the  play  of  the  inner  tendon  over  the 
condyle,  there  is  a  bursa,  which  generally  communicates  with  the 
knee-joint ;  and  in  the  substance  of  the  outer  tendon  is  commonly 
found  a  small  piece  of  fibro-cartilage.  Lastly,  between  the  gastro- 
cnemius and  soleus  is  the  tendon  of  the  plantaris. 

This  small  muscle  l  arises  from  the  rough  line 
leading  from  the  linea  aspera  to  the  outer  condyle 

1  This  is  the  representative  of  the  palmaris  longus  of  the  forearm.     In  man  it 
is  lost  on  the  calcaneurn,  but  in  monkeys,  who  have  prehensile  feet,  it  is  the 


MUSCLES   OF  THE   CALF.  675 

of  the  femur,  and  from  the  posterior  ligament  of  the  knee-joint.  It 
descends  close  to  the  inner  side  of  the  outer  head  of  the  gastro- 
cnemius,  having  a  fleshy  belly  for  about  two  inches,  and  terminates, 
a  little  below  the  knee,  in  a  long  thin  tendon,  which  can  be  traced 
down  the  inner  border  of  the  tendo  Achillis  to  the  calcaneum. 
This  muscle  is  occasionally  absent.  Its  nerve  comes  from  the 
internal  popliteal. 

This  muscle  arises  by  tendinous  fibres  from  the 
head  and  from  the  upper  third  of  the  posterior 
surface  of  the  fibula,  from  the  oblique  ridge  on  the  back  of  the 
tibia,1  from  about  the  middle  third  of  the  inner  border  of  this  bone, 
and  from  an  aponeurotic  arch  thrown  over  the  posterior  tibial 
vessels.  The  muscular  fibres  bulge  out  beyond  the  gastrocnemius, 
arid  terminate  on  a  broad  tendon,  which,  gradually  contracting, 
forms  a  constituent  part  of  the  tendo  Achillis.  The  muscle  lies 
upon  the  flexor  longus  digitorum,  the  tibialis  posticus,  the  flexor 
loiigus  hallucis,  and  the  posterior  tibial  vessels  and  nerve.  The 
soleus  is  supplied  with  blood  by  several  branches  from  the  pos- 
terior tibial ;  also  by  a  large  branch  from  the  peroneal.  Its  nerve 
conies  from  the  internal  popliteal  and  enters  the  top  of  the  muscle. 
This  is  an  important  muscle  in  a  surgical  point  of  view,  for  two 
reasons — (1)  by  reflecting  its  tibial  origin,  we  can  reach  the  pos- 
terior tibial  artery  ;  (2)  by  reflecting  its  fibular  origin  we  can  reach 
the  peroneal. 

The  tendo  Achillis,  the  common  tendon  of  the  gastrocnemius 
and  soleus,  begins  about  the  middle  of  the  leg,  and  is  at  first 
of  considerable  breadth,  but  it  gradually  contracts  and  becomes 
thicker  as  it  descends.  The  narrowest  part  of  it  is  about  one  inch 
and  a  half  above  the  heel ;  here,  therefore,  it  can  be  most  con- 
veniently arid  safely  divided  for  the  relief  of  club-foot.  There  is 
no  risk  of  injuring  the  deeper-seated  parts,  because  they  are 
separated  from  the  tendon  by  a  quantity  of  fat.  Its  insertion 

proper  tensor  muscle  of  the  plantar  fascia.  It  is  remarkably  strong  in  bears  and 
plantigrade  mammals. 

1  The  tibial  and  fibular  origins  of  the  soleus  constitute  what  some  anatomists 
describe  as  the  two  heads  of  the  muscle.  Between  them  descend  the  popliteal 
vessels,  protected  by  a  tendinous  arch. 

x  x  2 


C76 


POPLITEAL    VESSELS. 


FIG.  157. 


is  into  the  under  and  back  part  of  the  tuberosity  of  the  os  calcis. 
The  tendon  previously  expands  a  little :  between  it  and  the  bone 
is  a  bursa  of  considerable  size. 

The  action  of  the  gastrocnemius  and  soleus  is  to  raise  the  body 
on  the  toes.  Since  the  gastrocnemius  passes  over  two  joints,  it 
has  the  power  (like  the  rectus)  of  extending  the  one  while  it  bends 
the  other,  and  it  is,  therefore,  admirably  adapted  to  the  purpose  of 
walking.  For  instance,  by  first  extending  the  foot  it  raises  the 
body ;  and  then,  by  bending  the  knee,  it  transmits  the  weight  from 
one  leg  to  the  other.  Supposing  the  fixed  point  to  be  at  the  heel, 
the  gastrocnemius  is  also  concerned  in  keeping  the  body  erect,  for 
it  keeps  the  tibia  and  fibula  perpendicular  on  the  foot,  and  thus 
counteracts  the  tendency  of  the  body  to  fall  forwards. 

The  tendo  Achillis,  in  pointing  the  toes,  acts  upon  a  lever  of 

the  first  order.  The  fulcrum  is  at 
the  ankle-joint,  F  (fig.  157) ;  the  re- 
sistance, w,  at  the  toes ;  the  power 
at  the  heel,  P.  All  the  conditions 
are  those  of  a  lever  of  the  first  order. 
The  power  and  the  weight  act  in  the 
same  direction  on  opposite  sides  of 
the  fulcrum.  In  raising  the  body  on 
tiptoe,  the  tendo  Achillis  acts  as  a 
lever  of  the  second  order ;  the  fulcrum 
being  then  at  the  ball  of  the  great  toe,  and  the  weight  of  the  body 
at  the  ankle. 

After  passing  through  the  opening  in  the  tendon 
of  the  adductor  magnus,  the  femoral  artery  takes 
the  name  of  popliteal.  It  descends  nearly  per- 
pendicularly behind  the  knee-joint,  between  the 
origins  of  the  gastrocnemius,  as  far  as  the  lower  border  of  the 
popliteus,  where  it  divides  into  the  anterior  and  posterior  tibial. 
In  its  descent  it  lies,  first,  upon  the  lower  part  of  the  femur,  and 
here  it  is  slightly  overlapped  by  the  semimembranosus ;  next,  it 
lies  upon  the  posterior  ligament  of  the  knee-joint ;  and,  lastly,  upon 
the  popliteus.  At  its  lower  part  the  artery  is  covered,  at  first  by 
the  semimembranosus,  the  popliteal  vein,  the  internal  popliteal 


COURSE  AND 
KELATIONS  OF  THE 
POPLITEAL 
ARTERY. 


BRANCHES  OF  THE  POPLITEAL  ARTERY.  677 

nerve,  and  a  considerable  amount  of  fat ;  then,  lower  down,  by  the 
gastrocnemius  and  soleus,  and  it  is  crossed  by  the  plantaris.  The 
vein  closely  accompanies  the  artery,  and  is  situated  superficially 
with  regard  to  it,  and  rather  to  its  outer  side  in  the  first  part  of 
its  course.  The  internal  popliteal  nerve  runs  also  in  a  similar 
direction  with  the  vein,  but  is  still  more  superficial  and  to  the 
outer  side  (fig.  155).  The  vessels  and  the  nerve  are  surrounded 
by  fat,  and  one  or  two  lymphatic  glands  are  generally  found 
in  the  immediate  neighbourhood  of  the  artery,  just  above  the 
joint. 

The  branches  of  the  popliteal  artery  are — the  articular,  the 
vural,  and  the  cutaneous. 

There  are  five  articular  branches  for  the  supply  of  the  knee-joint  and 
the  articular  ends  of  the  bones  :  the  two  superior — external  and  internal 
— run,  one  above  each  condyle,  close  to  the  bone  ;  the  two  inferior — 
external  and  internal — run  below  the  joint. 

1.  The  superior  external  articular  artery  runs  above  the  external 
condyle,  passes   beneath  the   biceps,   and   through   the   intermuscular 
septum  :  it  then  divides  into  a  superficial  and  a  deep  branch  ;  the  super- 
ficial supplies  the  vastus  externus,  and  then  forms  part  of  the  patellar 
arterial  plexus  ;  the  deep  branch  keeps  close  to  the  femur  and  supplies 
the  knee,   forming  an  arch  above  the  joint  with  a  branch  from  the 
anastomotica  magna. 

2.  The  superior  internal  articular  artery  runs  above  the  internal 
condyle,  under  the  tendon  of  the  adductor  magtius  and  vastus  internus, 
and  divides  into  two  branches,  a  superficial  and  a  deep,  which  take  a 
corresponding  course  to  those  on  the  outer  side. 

3.  The  inferior  external  articular  artery  runs  under  the  gastro- 
cnemius, over  the  popliteus,  then,  passing  beneath  the  external  lateral 
ligament  and  the  tendon  of  the  biceps,  it  reaches  the  patella,  where  it 
breaks  up  into  branches  anastomosing  with  the  other  articular  arteries, 
and  the  recurrent  branch  of  the  anterior  tibial  artery. 

4.  The  inferior  internal  articular  artery  runs  between  the  tuberosity 
of  the  tibia  and  the  internal  lateral  ligament,  and  supplies  the  inner  and 
anterior  part  of  the  joint. 

5.  The   azygos   artery   is   given  off  from   the    deep   aspect  of   the 
popliteal,  pierces  the  ligamentum  posticum  Winslowii,  to  supply  the 
crucial  ligaments  and  the  synovial  membrane. 

The  several  articular  arteries  form  over  the  front  and  sides  of  the 


678  POPLITEAL   VEIN. 

joint  a  network  of  vessels,  which  anastomose,  superiorly,  with  the  de- 
scending branch  of  the  external  circumflex  and  the  anastomotica  magna  ; 
inferiorly,  with  the  anterior  tibial  recurrent ;  and  also  among  them- 
selves. It  is  mainly  through  these  channels  that  the  collateral  circula- 
tion is  established  in  the  leg  after  ligature  of  the  superficial  femoral. 

The  sural  arteries  proceed  one  to  each  head  of  the  gastrocnemius, 
and  are  proportionate  in  size  to  the  muscle  ;  one  or  two  branches  are 
distributed  to  the  soleus.  These  arteries  are  accompanied  by  branches 
of  the  internal  popliteal  nerve  for  the  supply  of  the  muscles. 

The  superior  muscidar  branches  supply  the  vasti  and  hamstring 
muscles,  and  inosculate  with  the  perforating  and  articular  arteries. 

Cutaneous  arteries  pass  down  between  the  gastrocnemius  and 
the  skin  supplying  the  integument  of  the  calf,  as  far  as  the  middle 
of  the  leg. 

POPLITEAL  This  vein  is  formed  by  the  junction  of  the  venae 

VEIN.  comites  of  the  anterior  and  posterior  tibial  arteries, 

and  is  situated  superficial  to  the  artery.  It  crosses  obliquely  from 
the  inner  to  the  outer  side  of  the  artery,  and  is  continued  upwards 
as  the  femoral.  It  receives  in  the  popliteal  space  the  short  saphena, 
the  articular,  and  sural  veins.  It  is  usually  provided  with  four 
valves. 

The  insertion  of  the  tendon  of  the  semi-membranosus  into  the 
head  of  the  tibia,  and  its  several  connections  (described  p.  670), 
should  now  be  fully  examined. 

This  triangular  muscle  arises  within  the  capsule 
of  the  knee-joint,  from  a  depression  on  the  outside 
of  the  external  condyle,  and  from  the  posterior  ligament  of  the 
knee,  by  a  thick  tendon,  which  runs  beneath  the  external  lateral 
ligament  and  the  tendon  of  the  biceps.  The  muscular  fibres 
gradually  spread  out,  and  are  inserted  into  the  triangular  surface 
of  the  tibia  above  the  soleal  ridge  on  the  bone,  and  into  the 
aponeurotic  expansion  covering  the  muscle.  It  is  supplied  by  a 
branch  of  the  internal  popliteal  nerve  which  enters  its  deep  surface. 
Its  action  is  to  flex  the  leg,  and  then  to  rotate  the  tibia  inwards. 
The  tendon  plays  over  the  articulation  between  the  tibia  and 
fibula  ;  and  a  bursa  intervenes,  which  generally  communicates  by 
a  wide  opening  with  the  knee-joint.  The  tendinous  origin  grooves 


DEEP  MUSCLES  OF  THE  BACK  OF  THE  LEG.        679 

the  external  semilunar  cartilage,  and  has  an  investment  from  the 
synovial  membrane  of  the  knee. 

Reflect  the  soleus  from  its  origin,  and  remove  it  from  the  deep- 
seated  muscles,  observing  at  the  same  time  the  numerous  arteries 
which  enter  its  under  surface.  This  done,  notice  the  deep  fascia 
which  separates  the  superficial  and  the  deep  layers  of  muscles  and 
which  binds  down  the  deep  muscles.  It  is  attached  to  the  margins 
of  the  tibia  and  the  fibula  on  either  side,  increases  in  strength 
towards  the  ankle,  and  forms  an  internal  annular  ligament  which 
confines  the  tendons  and  the  vessels  and  nerves  in  their  passage 
into  the  sole  of  the  foot. 

The  deep  fascia  should  now  be  removed  from  the  deep  muscles, 
which  must  be  cleaned  in  the  course  of  their  muscular  fibres. 

DEEP  MUSCLES  There  are  three  : — the  flexor  longus  digitorum 
ON  THE  BACK  OF  on  the  tibial  side ;  the  flexor  longus  hallucis  on  the 
THE  LEG.  fibular ;  the  tibialis  posticus  upon  the  interosseous 

membrane,  between  and  beneath  them  both. 

FLEXOR  This  arises  from  the   posterior  surface  of  the 

LONGUS  DIGI-  tibia,  commencing  below  the  popliteus,  and  ex- 

TOBUM-  tending  to  within  four  inches  of  the  lower  end  of 

the  bone,  also  from  the  fascial  septum  between  it  and  the  tibialis 
posticus.  The  fibres  terminate  on  a  tendon  which  is  placed  on  the 
tibial  side  of  the  muscle,  and  it  runs  through  a  groove  behind  the 
inner  ankle,  lined  by  a  special  synovial  sheath.  It  enters  the  sole 
and  divides  into  four  tendons,  which  are  inserted  into  the  ungual 
phalanges  of  the  four  outer  toes.  It  is  supplied  by  the  posterior 
tibial  nerve. 

FLEXOR  This  powerful  muscle  arises  from  the  lower  two- 

LONGUS  HALLUCIS.  thirds  of  the  posterior  surface  of  the  fibula,  from 
the  septum  between  it  and  the  peronei,  from  the  lower  part  of  the 
interosseous  membrane,  and  from  the  aponeurosis  over  the  tibialis 
posticus.  The  fibres  terminate  on  a  tendon  which  runs  through  a 
groove  on  the  back  of  the  lower  extremity  oi  the  tibia,  then  through 
the  groove  on  the  back  of  the  astragalus  thence  it  passes  through 
another  groove  on  the  under  aspect  of  the  sustentaculum  tali,  and 
is  inserted  into  the  ungual  phalanx  of  the  great  toe.  The  chief 
action  of  this  muscle  is  to  raise  the  body  on  the  tip  of  the  great 


680         DEEP  MUSCLES  OF  THE  BACK  OF  THE  LEG. 

toe.  It  is  essential  to  tlie  propulsion  of  the  body  in  walking.  It 
is  supplied  by  the  posterior  tibial  nerve. 

TIBIALIS  This  is  so  concealed  between  the  two  preceding 

POSTICUS.  muscles  that  it  cannot  be  properly  examined  with- 

out reflecting  them.  It  arises  by  two  processes  from  the  inter- 
osseous  membrane,  between  which  the  anterior  tibial  artery  passes 
forwards,  from  the  opposite  surfaces  of  the  tibia  and  fibula  for  about 
their  middle  three-fifths,  and  from  the  aponeurosis  covering  it.  In 
the  lower  part  of  the  leg  it  passes  between  the  tibia  and  the  flexor 
longus  digitorum.  Its  muscular  fibres  terminate  on  a  tendon  which 
comes  into  view  a  short  distance  above  the  inner  ankle,  and,  run- 
ning through  the  same  groove  with  the  tendon  of  the  flexor  longus 
digitorum,  enters  the  sole,  and  is  inserted  into  the  scaphoid  and 
internal  cuneiform  bones,  and  by  fibrous  prolongations  into  most 
of  the  tarsal  and  metatarsal  bones.  Its  action  is  to  bend  and  turn 
the  foot  inwards.  It  is  supplied  by  the  posterior  tibial  nerve.  The 
precise  situation  of  the  tendon  of  the  tibialis  posticus  is  interesting, 
surgically,  because  the  tendon  has  to  be  divided  for  the  relief  of 
talipes  varus.  It  lies  close  to,  and  parallel  with,  the  inner  edge  of 
the  tibia,  so  that  this  is  the  guide  to  it.  It  is  necessary  to  relax 
the  tendon,  while  the  knife  is  introduced  between  the  tendon  and 
the  bone.  Its  synovial  sheath  commences  about  1^  inch  above 
the  end  of  the  internal  malleolus,  and  is  consequently  opened  in 
the  operation. 

Attention  should  now  be  directed  to  the  internal  or  posterior 
annular  ligament,  which  binds  down  the  tendons  behind  the  inner 
ankle. 

It  is  attached  to  the  internal  malleolus  and  the  inner  border  of 
the  os  calcis.  It  is  continuous,  above,  with  the  deep  fascia  of  the 
leg,  below  with  the  plantar  fascia  and  the  abductor  hallucis.  Be- 
neath it  are  a  series  of  compartments  through  which  pass  the 
tendons  of  the  deep-seated  muscles  of  the  leg  and  the  vessels,  into 
the  sole  of  the  foot.  The  relative  positions  of  the  structures  passing 
under  this  ligament,  proceeding  from  within  outwards,  are — the 
tendons  of  the  tibialis  posticus,  and  the  flexor  longus  digitorum ; 
the  posterior  tibial  artery  accompanied  by  its  venae  comites ;  the 
posterior  tibial  nerve ;  and,  lastly,  the  tendon  of  the  flexor  longus 


COURSE    OF   THE    POSTERIOR   TIBIAL    ARTERY. 

hallucis.  Each  of  the  tendons  is  lined  by  a  separate  synovial 
membrane,  as  they  pass  behind  the  inner  ankle. 

COURSE  AND  This  artery  is  one  of  the  branches  into  which 

EELATIONS  OF  the  popliteal  divides  at  the  lower  border  of  the 

THE  POSTEEIOB  popliteus.  It  descends  between  the  superficial  and 
TIBIAL  ARTERY.  ^e  ^gep  muscles  at  the  back  of  the  leg  to  the 
interval  between  the  internal  malleolus  and  the  os  calcis,  and, 
entering  the  sole,  divides  beneath  the  abductor  hallucis  into  the 
external  and  internal  plantar  arteries.  It  lies,  first,  for  a  short 
distance,  upon  the  tibialis  posticus,  then,  on  the  flexor  longus 
digitorum ;  but  behind  the  ankle  it  is  in  contact  with  the  tibia,  so 
that  here  it  can  be  felt  beating,  and  effectually  compressed ;  and 
lastly  on  the  back  of  the  ankle-joint.  In  the  upper  part  of  its 
course,  it  runs  nearly  midway  between  the  bones,  and  is  covered  by 
the  gastrocnemius  and  soleus,  and  is  crossed  obliquely  from  within 
outwards  by  the  posterior  tibial  nerve.  To  tie  the  artery,  there- 
fore, in  this  situation,  is  difficult ;  but  in  the  lower  part  of  its  course 
it  gradually  approaches  the  inner  border  of  the  tibia,  from  which, 
generally  speaking,  it  is  not  more  than  half  or  three-quarters  of  an 
inch  distant.  Here,  being  comparatively  superficial,  it  may  easily  be 
tied.  Immediately  behind  the  internal  malleolus,  it  lies  between  the 
tendons  of  the  flexor  longus  digitorum  on  the  inner  side,  and  the 
flexor  longus  hallucis  on  the  outer.  It  has  two  venae  comites,  which 
communicate  at  intervals.  The  posterior  tibial  nerve  which  accom- 
panies the  artery  is  at  its  upper  third  on  its  inner  side,  then  crosses 
over  it,  and  for  the  lower  two-thirds  of  its  course  lies  external  to 
the  artery.  Its  branches  are  as  follows  : — 

a.  Numerous  musciilar  branches  to  the  soleus,  the  peronei,  and  the 
deep  muscles. 

b.  The  peroneal  is  a  branch  of  considerable  size — often  as  large  as 
the  posterior  tibial.     Arising  about  an  inch  below  the  division  of  the 
popliteal,  it  descends  close  to  the  interosseous  border  of  the  fibula,  and 
then  over  the  articulation  between  the  tibia  and  fibula  to  the  outer  part 
of  the  os  calcis,  where  it  inosculates  with  the  malleolar  and  plantar 
arteries.     All  down  the  leg  it  is  imbedded  among  the  muscles — being 
covered  :  first,  by  the  soleus,  afterwards,  by  the  flexor  longus  hallucis, 
by  the  fibres  of  which  it  is  more  or  less  surrounded.     To  both  these 


682  POSTERIOR   TIBIAL    ARTERY    AND    NERVE. 

muscles,  to  the  latter  especially,  it  sends  numerous  branches,  and  just 
above  the  ankle  it  gives  off  a  constant  one — the  anterior  peroneal — 
which  passes  through  the  iiiterosseous  membrane  to  the  under  aspect  of 
the  peroneus  tertius,  then  runs  in  front  of  the  inferior  tibio-fibular 
articulation,  and  inosculates  with  the  other  malleolar  and  tarsal 
arteries.  The  peroneal  supplies  the  nutrient  artery  of  the  fibula. 

c.  The  communicating  artery  passes  transversely  across  the  inter- 
osseous  membrane  about  an  inch  above  the  os  calcis.     It  runs  under 
the  tendon   of   the  flexor  longus  hallucis,  and  anastomoses  with  the 
peroneal  artery. 

d.  The  internal  calcanean  arteries,  several  in  number,   run  down, 
ramifying  over  the  posterior  and  inner  aspect  of  the  teiido  Achillis  and 
os  calcis  :  they  anastomose  with  the  internal  malleolar  and  peroneal 
arteries. 

e.  The  nutrient  artery  to  the  tibia  enters  the  bone  about  an  inch 
below  the  oblique  line,   the  foramen  through  which   it   passes  being 
directed  away  from  the  knee-joint. 

The  posterior  tibial  veins,  formed  by  the  junction  of  the  external 
and  internal  plantar  veins,  accompany  the  artery  as  vence  comites, 
and,  after  receiving  the  peroneal  veins,  join  with  the  veins  corre- 
sponding to  the  anterior  tibial  artery,  at  the  lower  border  of  the 
popliteus,  to  form  the  popliteal  vein. 

POSTERIOR  This  is  the  continuation  of  the  popliteal.     It 

TIBIAL  NERVE.  descends  close  to  its  corresponding  artery,  and, 
behind  the  inner  ankle,  divides  into  the  external  and  internal 
plantar  nerves.  In  the  first  part  of  its  course  the  nerve  lies  super- 
ficial to  the  artery,  and  rather  to  its  inner  side ;  but  lower  down 
the  nerve  crosses  the  artery,  and  passes  to  its  outer  side,  and  lies 
to  the  inner  border  of  the  tendo  Achillis.  It  supplies  branches  to 
the  three  deep-seated  muscles,  the  branch  to  the  flexor  longus 
hallucis  accompanying  the  peroneal  artery ;  and  a  cutaneous  branch 
— calcaneo-plantar — which  pierces  the  internal  annular  ligament, 
and  supplies  the  skin  of  the  heel  and  the  inner  side  of  the  sole  of 
the  foot. 


DISSECTION    OF    THE    SOLE    OF   THE    FOOT.  683 


THE   DISSECTION   OF   THE    SOLE   OF   THE   FOOT. 

SURFACE  The  skin  of  the  sole  is  remarkably  thick,  es- 

MARKING.  pecially  over  the  os  calcis  and  the  heads  of  the 

metatarsal  bones.  The  sole  of  the  foot  is  convex,  and  narrow 
behind,  but  gradually  increases  in  breadth  forwards  to  the  clefts  of 
the  toes.  The  inner  arch  of  the  foot,  extending  from  the  inner 
tuberosity  of  the  os  calcis  to  the  distal  end  of  the  first  metatarsal 
bone,  is  well  marked  in  a  well-developed  foot ;  along  this  arch  can 
be  distinguished  the  sustentaculum  tali ;  about  an  inch  in  front  of 
this  is  the  prominent  tubercle  of  the  scaphoid,  and  another  inch  in 
front  of  this  we  can  feel  the  articulation  between  the  internal 
cuneiform  and  the  base  of  the  metatarsal  bone  of  the  great  toe. 
The  outer  arch  of  the  foot  is  neither  so  deep  nor  so  long  as  the 
inner ;  it  extends  from  the  external  tubercle  of  the  os  calcis  to  the 
base  of  the  metatarsal-  bone  of  the  little  toe,  and  along  it  we  can 
recognise  the  peroneal  tubercle  of  the  os  calcis  and  the  base  of  the 
fifth  metatarsal  bone.  The  transverse  arch,  between  the  heads  of 
the  metatarsal  bones,  is  not  well  marked  through  the  skin,  for  it  is 
obscured  by  the  tense  plantar  fascia.  The  plantar  fascia  can  be 
made  tense  by  extending  the  foot,  when  its  narrowest  part  is  seen 
to  be  about  one  inch  in  front  of  the  os  calcis.  The  course  of  the 
external  plantar  artery  is  indicated  by  a  line  drawn  from  the  in- 
ternal tubercle  of  the  os  calcis  to  the  base  of  the  fifth  metatarsal 
bone ;  that  of  the  internal  plantar  artery  by  a  line  drawn  from  the 
same  tuberosity  to  the  first  interosseous  space. 

The  foot  should  be  firmly  fixed  to  a  block  with 
the  sole  directed  towards  the  dissector,  and  the  toes 
either  fastened  by  string  or  nailed  to  the  block,  so  as  to  put  the 
plantar  fascia  on  the  stretch.  Make  a  perpendicular  incision  down 
the  middle  of  the  sole ;  another  transverse  one  across  the^  foot  at 
the  clefts  of  the  toes,  and  continue  the  perpendicular  incision  along 
the  middle  of  the  toes  to  their  terminations.  Reflect  the  skin,  and 
notice  the  peculiar  structure  of  the  subcutaneous  tissue.  It  is 
composed  of  globular  masses  of  fat,  separated  by  strong  fibrous 
.septa,  and  forms  elastic  pads,  especially  marked  at  the  heel,  and  at 


684  SOLE   OF  THE   FOOT. 

the  ball  of  the  great  and  the  little  toes ;  these  being  the  points 
which  form  the  tripod  supporting  the  arch  of  the  foot. 

In  removing  the  subcutaneous  tissue  from  the  ball  of  the  great 
and  the  little  toes,  we  often  meet  with  bursae,  simple  or  multilocular. 
They  are  generally  placed  between  the  skin  and  the  sesamoid  bones, 
and  have  remarkably  thick  walls.  Frequently  an  artery  and  nerve 
can  be  traced  running  directly  through  one  of  these  sacs,  which 
explains  the  acute  pain  produced  by  their  inflammation. 

CUTANEOUS  I11   the  fat   the    student   must  make   out   the 

NERVES.  cutaneous   branch    of  the    posterior   tibial   nerve,, 

which  supplies  the  skin  of  the  sole  of  the  foot  and  the  heel ;  the 
remainder  of  the  sole  is  supplied  by  small  branches  of  the  plantar 
nerves  which  come  through  the  fascia,  as  in  the  palm  of  the  hand. 
PLAKTAB  This  is  a  remarkably  dense  white  and  glistening 

FASCIA.  fascia.     It  extends  from  the  under  and  back  part 

of  the  os  calcis  to  the  distal  extremities  of  the  metatarsal  bones. 
It  is  divided  into  a  strong  central  and  two  lateral  less  dense  por- 
tions ;  from  which  prolongations  pass  deeply  inwards,  separating 
the  lateral  from  the  central  muscles.  The  middle  portion,  cover- 
ing the  flexor  brevis  digitorum,  is  narrow  behind,  and,  as  it  passes 
forwards  towards  the  toes,  is  spread  out,  and  strengthened  by  trans- 
verse fibrous  bands.  The  inner  portion  is  comparatively  thin,  and 
surrounds  the  abductor  hallucis,  becoming  continuous  posteriorly 
with  the  internal  annular  ligament.  The  outer  portion  is  thicker 
than  the  inner,  especially  as  it  passes  forwards  to  be  attached  to 
the  proximal  end  of  the  fifth  metatarsal  bone.  It  covers  the 
abductor  minimi  digiti.  Both  the  inner  and  the  outer  portions  are 
continuous  with  the  fascia  of  the  dorsum  of  the  foot  round  the 
inner  and  outer  borders  of  the  foot,  and  with  the  central  portion  of 
the  plantar  fascia  towards  the  centre  of  the  sole. 

Near  the  distal  ends  of  the  metatarsal  bones,  the  central  part 
divides  into  five  portions  :  each  of  these  subdivides  into  two  slips, 
which  embrace  the  corresponding  flexor  tendons,  and  are  attached 
to  the  metatarsal  bones  and  their  connecting  ligaments.  Between 
the  primary  divisions  of  the  fascia — that  is,  in  a  line  between  the 
toes — are  seen  the  digital  vessels  and  nerves.  This  arrangement  is 
in  all  respects  like  that  in  the  palm. 


SUPERFICIAL  MUSCLES  OF  THE  SOLE  OF  THE  FOOT.     G85 

In  the  interdigital  folds  of  the  skin,  there  are  also  ligamentous 
fibres,  which  run  from  one  side  of  the  foot  to  the  other,  and  answer 
the  same  purpose  as  those  in  the  hand  (p.  355). 

The  plantar  fascia  must  be  partially  removed  to  examine  the 
muscles.  Towards  the  os  calcis  its  removal  is  not  accomplished 
without  some  difficulty,  since  the  muscles  arise  from  it. 

SUPERFICIAL  After  the  removal  of  the  fascia  three  muscles 

MUSCLES.  are  exposed.     All  arise  from  the  os  calcis  and  the 

fascia,  and  proceed  forwards  to  the  toes.1  The  central  one  is  the 
flexor  brevis  digitorum,  the  one  on  the  inner  side  is  the  abductor 
hallucis,  and  the  outer  one  is  the  abductor  minimi  digiti. 

ABDUCTOR  This  muscle  arises  from  the  internal  tubercle  of 

HALLUCIS.  the  os  calcis,  from   the   plantar  fascia,  from  the 

internal  annular  ligament,  and  from  the  intermuscular  septum 
between  it  and  the  flexor  brevis  digitorum.  Its  origin  arches  over 
the  plantar  vessels  and  nerves  in  their  passage  to  the  sole.  The 
fibres  run  along  the  inner  side  of  the  sole,  and  terminate  on  a 
tendon,  which  is  inserted,  with  the  inner  tendon  of  the  flexor  brevis 
hallucis,  into  the  inner  side  of  the  base  of  the  first  phalanx  of  the 
great  toe,  through  the  medium  of  the  internal  sesamoid  bone.  Its 
nerve  comes  from  the  internal  plantar. 

ABDUCTOR  This  muscle  lies  on  the  outer  border  of  the  foot, 

MINIMI  DIGITI.  and  has  a  very  strong  origin  from  the  under  surface 
of  the  os  calcis,  from  its  external  tubercle,  from  the  plantar  fascia, 
and  from  the  external  intermuscular  septum  between  it  and  the 
flexor  brevis  digitorum.  Some  of  its  fibres  terminate  on  a  tendon 
which  is  inserted  into  the  proximal  end  of  the  metatarsal  bone  of 
the  little  toe ;  but  the  greater  part  run  on  to  a  tendon  which  is 
inserted,  with  the  flexor  brevis  minimi  digiti,  into  the  outer  side  of 
the  first  phalanx  of  the  little  toe.  It  is  supplied  by  the  external 
plantar  nerve. 

FLEXOR  BREVIS          This  muscle  arises  from  the  under  surface  of  the 
DIGITORUM.  os  calcis,  between  the   two  preceding,  from  the 

deep  surface  of  the  plantar  fascia  and  the  intermuscular  septa. 
It  passes  forwards  and  divides  into  four  tendons,  which  run  super- 

1  They  are  separated  from  each  other  by  strong  perpendicular  partitions — 
intermuscular  septa — which  pass  in  from  the  plantar  fascia. 


686 


MUSCLES  OF  THE  SOLE  OF  THE  FOOT. 


ficial  to  those  of  the  long  flexor.  Cut  open  the  sheath  which  con- 
tains them  ;  follow  them  on  to  the  toes,  to  see  that  each  bifurcates 
over  the  first  phalanx,  to  allow  the  long  tendon  to  pass  through ; 
then  the  two  slips,  reuniting,  are  inserted  into  the  sides  of  the 
second  phalanx.  The  same  arrangement  prevails  in  the  fingers. 
It  is  supplied  by  the  internal  plantar  nerve. 

The  three  superficial  muscles  should  now  be  reflected,  by  sawing 
off  about  half  an  inch  of  the  os  calcis,  and  then  turning  it  downwards 

FIG.  158. 


1  Abductor      mi- 
nimi digiti. 

2.  Flexor  accesso- 

rius. 

3.  Abductor     hal- 

lucis. 

4.  External  plantar 

artery     and 
nerve. 

5.  Tendon  of  flexor 

longus  hallucis. 

6.  Internal  plantar 

artery     and 
nerve. 


8.  Flexor     brevis- 
miuimi  digiti. 

9.  Lumbricales. 

10.  Internal    plan- 
tar nerve. 

11.  Tendons  of  the 

flexor  brevis 
digitorum  bi- 
furcating, for 
the  passage  of 
the  tendons  of 
the  flexor  lon- 
gus digitorum. 


MUSCLES,    VESSELS,    AND    SERVES    OF    THE    SOLE    OF    THE    EIGHT    FOOT,    AFTER 
REFLECTION    OF    THE    FLEXOR    BREVIS    DIGITORUM. 

with  the  muscles  attached  to  it.  This  done,  we  bring  into  view -the 
plantar  vessels  and  nerves,  and  the  second  layer  of  muscles — i.e.  the 
long  flexor  tendon  of  the  great  toe,  that  of  the  other  toes,  and  the 
flexor  accessorius. 

Tracing  this  tendon  into  the  sole,  you  find  that 
an  accessory  muscle  is  attached  to  it.  The  flexor 
accessorius  arises  by  muscular  fibres  from  the  in- 
ner concave  side  of  the  os  calcis  and  the  calcaneo- 
scaphoid  ligament,  and  by  tendinous  fibres  from  the 


TENDON  OF  THE 
FLEXOR  LONGUS 
DIGITORUM. 

MUSCULUS 
ACCESSOHIUS. 


PLANTAR    ARTERIES.  687 

outer  side  in  front  of  the  external  tubercle,  and  from  the  long  plantar 
ligament.  Its  fibres  run  straight  forwards,  and  are  inserted  into 
the  fibular  side  of  the  upper  surface  of  the  tendon,  so  that  their 
action  is  not  only  to  assist  in  bending  the  toes,  but  to  make  the 
common  tendon  pull  in  a  straight  line  towards  the  heel ;  which , 
from  its  oblique  direction,  it  could  not  do  without  the  accessory 
muscle.  The  common  tendon  then  divides  into  four,  one  for  each 
of  the  four  outer  toes.  These  run  in  the  same  sheath  with  the 
short  tendons,  and,  after  passing  through  their  divisions,  are  inserted 
into  the  bases  of  the  ungual  phalanges.  Respecting  the  manner 
in  which  the  tendons  are  confined  by  fibrous  sheaths,  and  lubri- 
cated by  a  synovial  lining,  what  was  said  of  the  fingers  (p.  363) 
applies  equally  to  the  toes.  The  flexor  accessorius  is  supplied  by 
the  external  plantar  nerve. 

These  four  little  muscles  are  placed  between  the 

LUMBRICALES.  . 

long  flexor  tendons.  J^ach,  excepting  the  most  in- 
ternal, which  is  attached  only  to  the  inner  side  of  the  tendon  going 
to  the  second  toe,  arises  from  the  adjacent  sides  of  two  tendons, 
proceeds  forwards,  and  then,  sinking  between  the  toes,  terminates 
in  an  aponeurosis  which  passes  round  the  inner  side  of  the  four 
outer  toes,  and  joins  the  extensor  tendon  on  the  dorsuni  of  the  first 
phalanges  of  the  toes.  Concerning  their  use,  refer  to  p.  365.  The 
two  outer  lumbricales  are  supplied  by  the  external,  the  two  inner 
by  the  internal  plantar  nerve. 

Now  trace  the  long  flexor  tendon  of  the  great  toe.  From  the 
groove  in  the  astragalus  it  runs  along  the  groove  in  the  lesser  tube- 
rosity  of  the  os  calcis,  above,  that  is  nearer  to  the  bones  than  the 
tendon  of  the  flexor  longus  digitorum,  between  the  two  heads  of  the 
flexor  brevis  hallucis,  and  then  straight  to  the  base  of  the  last 
phalanx.  It  crosses  the  long  flexor  tendon  of  the  toes,  and  the  two 
tendons  are  connected  by  an  oblique  slip ;  so  that  we  cannot  bend 
the  other  toes  without  the  great  toe. 

PLANTAR  The  posterior  tibial  artery,  having  entered  the 

ARTEHIES.  sole  between  the  origins  of  the  abductor  hallucis, 

divides  into  the  external  and  internal  plantar  arteries. 

The  internal  plantar  artery  is  smaller  than  the  external  plantar 
artery :  it  passes  forwards  between  the  abductor  hallucis  and  the 


688 


PLANTAR   ARTERIES. 


FIG.  159. 


flexor  brevis  digitorum  to  the  base  of  the  great  toe,  and  then  is 
continued  along  the  inner  side  of  that  toe,  where  it  terminates  in 
small  inosculations  with  the  digital  arteries.  Its  chief  use  is  to 
supply  the  muscles  between  which  it  runs. 

The  external  plantar  is  the  principal  artery  of  the  sole,  and 
alone  forms  the  plantar  arch  (fig.  159).  It  runs  obliquely  outwards 
across  the  sole  towards  the  base  of  the  fifth  metatarsal  bone  ;  then, 
sinking  deeply,  it  bends  inwards  across  the 
bases  of  the  metatarsal  bones,  and  inoscu- 
lates with  the  communicating  branch  of  the 
dorsalis  pedis  in  the  first  interosseous  space. 
At  first  it  lies  between  the  os  calcis  and  the 
abductor  hallucis ;  it  then  passes  between 
the  flexor  brevis  digitorum  and  the  flexor 
accessorius ;  still  continuing  its  course  for- 
Avards,  it  is  placed  between  the  flexor  brevis 
digitorum  and  the  flexor  brevis  minimi  digiti, 
covered  only  with  skin,  fat  and  plantar  fascia ; 
and,  lastly,  it  lies  deep  beneath  the  flexor 
tendons,  the  lumbricales,  the  adductor  hal- 
lucis, upon  the  interossei  muscles.  Deeply 
seated  as  it  appears  to  be,  that  part  of  its 
curve  near  the  fifth  metatarsal  bone  lies 
immediately  beneath  the  fascia. 

The  external  plantar  sends  two  or  three 
internal  calcanean  branches  to  the  skin  of 
the  heel — one  round  the  outer  edge  of  the 
foot,  which  anastomoses  with  the  tarsal  and 
metatarsal  branches  of  the  arteria  dorsalis 

pedis;  and  also  some  cutaneous  branches  which  emerge  between 
the  adjacent  borders  of  the  flexor  brevis  minimi  digiti  and  the 
flexor  brevis  digitorum.  It  also  gives  off : — 

The  digital  arteries,  four  in  number,  which  arise  from  the 
deepest  part  of  the  arch.  They  supply  both  sides  of  the  fifth, 
fourth,  third  and  the  outer  side  of  the  second  toes ;  and,  running 
forwards  along  the  interossei,  divide  at  the  clefts  of  the  toes  into  two 
branches,  which  supply  the  contiguous  sides  of  the  adjacent  toes. 


1.  Internal  plantar  artery. 

2.  External          ditto. 


PLANTAR  NERVES.  689 

At  the  point  of  division  the  digital  arteries  send  upwards  through 
the  front  part  of  the  three  outer  interosseous  spaces,  small  branches, 
anterior  perforating,  which  anastomose  on  the  dorsum  of  the  foot 
with  the  interosseous  arteries. 

The  posterior  perforating  are  three  branches  which  perforate  the 
back  part  of  the  three  outer  interosseous  spaces,  and  inosculate  with 
the  dorsal  interosseous  arteries  at  each  end  of  the  spaces. 

The  digital  artery,  supplying  the  inner  side  of  the  great  toe  and 
the  adjacent  sides  of  the  great  and  second  toes,  comes  from  the 
communicating  branch  of  the  dorsal  artery  of  the  foot  which  pierces 
the  back  of  the  first  interosseous  space  to  get  to  the  sole  of  the 
foot.  It  is  joined  here  by  a  branch  from  the  external  plantar 
artery. 

PLANTAB  The  posterior  tibial  nerve  divides,  like  the  artery, 

NERVES.  jnto  an  external  and  internal  plantar. 

The  internal  plantar  nerve  is  the  larger,  and  runs  with  its  corre- 
sponding artery  along  the  inner  side  of  the  foot  between  the  ab- 
ductor hallucis  and  the  flexor  brevis  digitorum  ;  in  this  part  of  its 
course  it  distributes  cutaneous  branches  to  supply  the  skin  of  the 
sole,  muscular  branches  to  the  two  above-named  muscles,  and  articu- 
lar branches  to  the  joints  of  the  tarsus  and  metatarsus.  It  then 
gives  off  four  digital  branches  which  supply  the  three  inner  toes 
and  a  half,  like  the  median  in  the  palm  :  the  first  digital  branch 
runs  along  the  inner  side  of  the  great  toe  to  its  tip,  and  in  its 
passage  gives  off  a  branch  to  the  flexor  brevis  hallucis  ;  the  second 
divides  into  two  branches,  one  which  supplies  the  inner  lumbricalis, 
and  the  other,  the  contiguous  borders  of  the  great  and  second  toes ; 
the  third  sends  a  filament  to  the  second  lumbrical,  and  then  bifur- 
cates for  the  supply  of  the  adjacent  sides  of  the  second  and  third 
toes  ;  the  fourth,  after  receiving  a  communicating  filament  from  the 
external  plantar  nerve,  is  distributed  to  the  contiguous  sides  of  the 
third  and  fourth  toes.  These  digital  nerves  send  off  small  branches 
to  supply  the  dorsum  of  the  toes  at  the  last  phalanges. 

The  external  plantar  nerve  passes  obliquely  forwards  and  out- 
wards with  the  artery  of  the  same  name,  passing  between  the 
flexor  accessorius  and  the  flexor  brevis  digitorum,  to  the  former  of 
which  it  sends  a  muscular  branch ;  it  then  runs  along  the  inner 

Y  Y 


690          MUSCLES  OF  THE  SOLE  OF  THE  FOOT. 

border  of  the  abductor  minimi  digiti,  supplies  it,  and  then  divides 
into  two  branches,  a  superficial  and  a  deep. 

The  superficial  branch  sends  one  digital  branch  which  supplies  the 
flexor  brevis  minimi  digiti,  the  plantar  and  dorsal  interossei  of 
the  fourth  space,  and  the  outer  side  of  the  little  toe  ;  and  another 
and  larger  digital  branch  which  supplies  the  contiguous  sides  of  the 
fourth  and  fifth  nerves,  and  sends  a  communicating  filament  to  the 
outer  digital  branch  of  the  internal  plantar  nerve. 

The  deep  branch  accompanies  the  plantar  arch  deep  into  the 
sole  of  the  foot,  beneath  the  adductor-  hallucis,  and  furnishes 
branches  to  the  plantar  and  dorsal  interossei  of  all  the  interosseous 
spaces  except  the  fourth,  the  adductor  hallucis,  the  transversal  is 
pedis,  and  the  two  outer  lumbricales. 

THIRI>  LAYER  Having  traced  the  principal  vessels  and  nerves, 

OF  MUSCLES.  divide  them  with  the  flexor  tendons  near  the  os 

calcis,  and  turn  them  down  towards  the  toes,  to  expose  the  deep 
muscles  in  the  sole.  These  are,  the  flexor  brevis  and  adductor 
hallucis,  the  flexor  brevis  minimi  digiti,  and  the  transversalis  pedis. 

FLEXOR  BREVIS          This  muscle  arises  by  a  pointed  tendon  from  the 
HALLUCIS.  cuboid  bone,  and  from  the  fibrous  prolongation  of 

the  tibialis  posticus  into  the  external  cuneiform  It  proceeds  along 
the  metatarsal  bone  of  the  great  toe,  and  divides  into  two  portions, 
which  run  one  on  each  side  of  the  long  flexor  tendon,  and  are  in- 
serted by  tendons  into  the  sides  of  the  first  phalanx  of  the  great  toe. 
The  inner  tendon  is  inseparably  connected  with  the  abductor 
hallucis,  the  outer  with  the  adductor  hallucis.  In  each  tendon 
there  is  a  sesamoid  bone.  These  bones  not  only  increase  the 
strength  of  the  muscle,  but,  both  together,  form  a  pulley  for  the 
free  play  of  the  long  flexor  tendon  ;  so  that  in  walking  the  tendon 
is  not  pressed  upon.  Its  nerve  comes  from  the  internal  plantar 
(fig.  160,  fc). 

ADDUCTOR  This  very  powerful  muscle  arises  from  the  bases 

HALLUCIS.  of  the  second,  third  and  fourth  metatarsal  bones, 

and  from  the  sheath  of  the  peroneus  longus.  Passing  obliquely 
forwards  and  inwards  across  the  foot,  it  is  inserted  through  the  ex- 
ternal sesamoid  bone  into  the  outer  side  of  the  base  of  the  first 
phalanx  of  the  great  toe  together  with  the  inner  head  of  the  flexor 


MUSCLES  OF  THE  SOLE  OF  THE  FOOT. 


691 


brevis.  This  muscle  greatly  contributes  to  support  the  arch  of  the 
foot.  Like  the  adductor  of  the  thumb,  it  should  be  considered  as 
an  interosseous  muscle.  Its  nerve  is  derived  from  the  external 
plantar  (fig.  160,  i). 

FLEXOR  BBEVIS          This  little  muscle  rests  on  the  fifth  metatarsal 
MINIMI  DIGITI.         bone,  and  arises  from  the  base  of  the  fifth  meta- 


a.  Abductor  hallucis. 
6.  Plexor  brevis 
digitorum. 

c.  Abductor  minimi 

digiti. 

d.  Tendon   of    pero- 

neus  longus. 

«,  n.  Flexor  longus 
hallucis. 

/.  Tendon  of  flexor 
longus  digito- 
rum. 


d 


g.  Flexus      accesso- 

rius. 
h.  Flexor  brevia 

minimi  digiti. 
t-.  Adductor 

hallucis. 
i.  Flexor  brevis 

hallucis. 
/.  Interossei. 
m.  Transversalis 

pedis. 
o.  Tibialis  postious. 


VIEW    OF    THE    THIRD    LAYER   OF    MUSCLES    OF    THE    FOOT. 

tarsal  bone  and  the  sheath  of  the  peroneus  longus ;  it  proceeds  for- 
wards along  the  bone,  and  is  inserted  into  the  outer  side  of  the  base 
of  the  first  phalanx  of  the  little  toe.  It  is  supplied  by  the  external 
plantar  nerve  (fig.  160,  Ti). 


692  INTEROSSEI   PEDIS. 

TRANSVERSALIS  This  slender  muscle  runs  transversely  across  the 

PEDIS.  distal  ends  of  the  metatarsal  bones.     It  arises  by 

little  fleshy  slips  from-  the  inferior  metatarso-phalangeal  ligaments 
of  the  three  outer  toes,  and  the  transverse  ligament  of  the  meta- 
tarsus, and  is  inserted  into  the  outer  side  of  the  first  phalanx  of 
the  great  toe  with  the  adductor  hallucis,  of  which  it  ought  to  be 
considered  a  part.  Its  nerve  comes  from  the  external  plantar 
(fig.  160,  m). 

The  fourth  layer  of  muscles  consists  of  the  interossei. 

These  muscles  are  arranged  nearly  like  those  in 
the  hand.  They  occupy  the  intervals  between  the 
metatarsal  bones,  and  are  seven  in  number,  four  being  on  the  dorsal 
aspect  of  the  foot,  three  on  the  plantar.  The  four  dorsal  interossei 
arise  each  by  two  heads  from  the  contiguous  sides  of  the  metatarsal 
bones,  and  are  inserted  into  the  bases  of  the  first  phalanges,  and 
into  the  aponeurosis  of  the  extensor  communis  digitorum  on  the 
dorsurn  of  the  toes.  The  first  is  inserted  into  the  inner  side  of  the 
second  toe ;  the  remaining  three  into  the  outer  sides  of  the  second, 
third,  and  fourth.  The  plantar  interossei,  three  in  number,  arise 
from  the  inner  sides  and  under  surfaces  of  the  third,  fourth,  and 
fifth  metatarsal  bones,  and  are  inserted  respectively  into  the 
inner  sides  of  the  bases  of  the  first  phalanges  of  the  third,  fourth,  and 
fifth  toes,  and  into  the  aponeurosis  of  the  common  extensor  tendon. 

The  use  of  the  interosseous  muscles  is  to  draw  the  toes  to  or 
from  each  other,  and  they  do  the  one  or  the  other  according  to  the 
side  of  the  phalanx  on  which  they  act.  Now,  if  we  draw  a  longi- 
tudinal line  through  the  second  toe,  we  find  that  all  the  dorsal 
muscles  draw  from  that  line,  and  the  plantar  toivards  it.  This  is 
the  key  to  the  action  of  them  all.  A  more  detailed  account  of 
these  muscles  is  given  in  the  dissection  of  the  hand  (p.  399).  Be- 
tween the  tendons  of  the  interossei,  that  is,  between  the  distal  ends 
of  the  metatarsal  bones,  there  are  bursae  which  facilitate  movement. 
They  sometimes  become  enlarged  and  occasion  painful  swellings 
between  the  roots  of  the  toes.  The  flexor  brevis  minimi  digiti, 
the  transversalis  pedis,  and  all  the  interossei,  are  supplied  by  the 
external  plantar  nerve. 

Now  trace  the  tendons  of  the  peroneus  longus   and  tibialis 


LIGAMENTS   OF   THE   PELVIS.  693 

posticus.  The  tendon  of  the  peroneus  longus  is  the  deepest  in  the 
sole.  It  runs  through  a  groove  in  the  cuboid  bone  obliquely  across 
the  sole  towards  its  insertion  into  the  outer  side  of  the  base  of  the 
metatarsal  bone  of  the  great  toe  and  into  the  internal  cuneiform 
bone ;  not  infrequently  it  has  a  fasciculus  of  attachment  into  the 
second  metatarsal  bone.  It  is  confined  in  a  strong  fibrous  sheath, 
lined  throughout  by  synovial  membrane. 

The  tendon  of  the  tibialis  posticus  may  be  traced  over  the 
internal  lateral  ligament  of  the  ankle,  and  thence  under  the  head 
of  the  astragalus  to  the  tuberosity  of  the  scaphoid,  and  the  internal 
cuneiform  bones.  Prolongations  are  sent  off  to  the  cuneiform 
bones,  to  the  cuboid,  to  the  sustentaculum  tali,  and  to  the  bases  of 
the  second,  third,  and  fourth  metatarsal  bones.  Observe  that  the 
tendon  contributes  to  support  the  head  of  the  astragalus,  and  that 
for  this  purpose  it  often  contains  a  sesamoid  bone.  This  is  one  of 
the  many  provisions  for  the  maintenance  of  the  arch  of  the  foot. 


DISSECTION   OF  THE  LIGAMENTS. 

sacrum  ig  united  to  the  last  lumbar  ver- 


L      IENTS  OF 

THE  PELVIS  WITH  tebra  in  the  same  manner  as  one  vertebra  is  to 
THE  FIFTH  LUMBAR  another  —  viz.,  by  the  prolongation  of  the  anterior 
and  posterior  common  ligaments,  the  interver- 
tebral  fibro-cartilage,  the  ligamenta  subflava,  supra-  and  inter- 
spinous  ligaments,  and  the  capsular  ligaments.  The  student 
should,  therefore,  refer  to  the  description  of  the  ligaments  of  the 
spine  (p.  295). 

The  ilio-lumbar  ligament  is  very  strong,  and  extends  directly 
outwards  from  the  tip  of  the  transverse  process  of  the  last  lumbar 
vertebra  to  the  crest  of  the  ilium  (fig.  162). 

The  lumbo-sacral  ligament  varies  much  in  its  extent  and  attach- 
ment, and  passes  from  the  anterior  and  lower  border  of  the  trans- 
verse process  of  the  fifth  lumbar  vertebra  to  the  lateral  part  of 
the  base  of  the  sacrum  ;  the  fibres  as  they  descend  obliquely  out- 
wards become  frayed  out,  joining  in  part  the  anterior  sacro-iliac 
ligament. 


694  SACRO-ILIAC   ARTICULATION. 

LIGAMENTS  OF  The  sacrum  is  connected  with  the  coccyx  by 

THE  SACRUM  AND  means  of  an  anterior  and  a  posterior  sacro-coc- 
COCCYX.  cygeal  ligament  and  by  an  intervertebral  fibro- 

cartilage. 

The  posterior  sacro-coccygeal  ligament  is  a  flattened  fasciculus  of 
fibres  extending  from  the  lower  margin  of  the  sacral  canal  to  the 
posterior  surface  of  the  coccyx  :  this  ligament  closes  in  the  inferior 
termination  of  the  sacral  canal. 

The  anterior  sacro-coccygeal  ligament  is  a  thin  band  of  fibres 
passing  along  the  front  of  the  sacrum  to  the  coccyx. 

The  intervertebral  disc  is  a  thin  layer  of  fibro-cartilage,  firm  in 
the  centre,  thinner  laterally  and  in  front  and  behind,  with  occa- 
sionally a  synovial  membrane.  Laterally,  there  are  some  irregular 
strands  of  fibres,  the  lateral  ligaments,  which  extend  from  the 
lower  lateral  part  of  the  sacrum  to  the  transverse  process  of  the 
coccyx. 

The  segments  of  the  coccyx  are  in  early  life  separated  by 
interposed  fibro-cartilages,  which  subsequently  ossify ;  they  have 
in  front  and  behind  a  continuation  of  the  anterior  and  posterior 
common  ligaments. 

The  innominate  bones  are  connected  to  each  other  in  front,  con- 
stituting the  symphysis  pubis ;  posteriorly,  to  the  sacrum,  forming 
the  sacro-iliac  symphysis. 

SACEO-ILIAC  This  articulation  is  an  example  of  that  form 

ARTICULATION.  of  amphiarthrodial  joints  where  the  surfaces  are 
covered  with  fibro-cartilage,  with  an  incomplete  synovial  mem- 
brane. The  articulation  is  formed  between  the  auricular  surfaces 
of  the  lateral  portions  of  the  sacrum  and  ilium.  The  anterior  part 
of  the  bones  forming  this  articulation  is  incrusted  with  articular 
cartilage,  of  which  the  shape  is  like  that  of  the  ear.  Later  in  life 
these  two  surfaces  are  more  or  less  connected  by  thin  interarticular 
transverse  fibres,  so  that  the  interval  between  them  is  very  irre- 
gular, and  frequently  contains  yellow,  viscid  material.  In  front  of 
the  articulation  there  is  the  anterior  sacro-iliac  ligament,  and 
behind,  the  posterior  sacro-iliac  ligament. 

The  anterior  sacro-iliac  ligament  consists  of  thin  ligamentous 
fibres  passing  in  front  of  the  sacrum  and  ilium. 


SACRO-ILIAC   LIGAMENTS. 


695 


The  posterior  sacro-iliac  ligament  is  composed  of  fibres  much 
stronger  and  more  marked,  which  pass  behind  the  articulation.  It 
consists  of  two  portions  :  the  upper,  or  horizontal,  extends  from  the 
upper  two  transverse  tubercles  of  the  sacrum,  and  is  attached  to 
the  rough  surface  of  the  ilium  above  the  auricular  surface;  the 
lower,  or  oblique,  is  a  well-marked  fasciculus  of  fibres,  the  oblique 
sacro-iliac  ligament,  passing  from  the  posterior  superior  spine  to 
the  third  segment  of  the  sacrum. 

SACBO- SCIATIC  These  are  two  strong  ligaments  passing  from 

LIGAMENTS.  the  sacrum  to  the  ischium. 

FIG.  161. 


Great   sacro  -  sciatic 
ligament.    .    .    . 

Lesser  sacro  -  sciatic 
ligament.    .    .    . 


Ilio-femoral  or  acces- 
sory ligament  of 
the  hip-joint. 


The  great  sacro-sciatic  ligament  is  triangular  and  thick ;  but 
narrower  in  the  middle  than  at  either  extremity.  Its  base  is  broad, 
and  is  attached  to  the  posterior  inferior  iliac  spine,  and  to  the 
sides  of  the  sacrum  and  coccyx ;  rapidly  narrowing,  it  descends 
obliquely  outwards  towards  the  tuberosity  of  the  ischium,  where  it 
again  expands  to  be  attached  to  the  inner  margin  of  this  bone. 
This  attached  portion  is  continued  upwards  for  some  distance  as  a 
prolongation,  the  falciform  process,  into  the  inner  margin  of  the 
ramus  of  the  ischium,  where  it  becomes  continuous  with  the 
obturator  fascia,  forming  a  protection  for  the  pudic  vessels  and 
nerve. 


696  PUBIC   SYMPHYSIS. 

The  lesser  sacro-sciatic  ligament  lies  in  front  of  the  preceding 
ligament,  and,  like  it,  is  triangular,  though  smaller  and  shorter. 
It  passes  from  the  sides  of  the  sacrum  and  coccyx  to  the  spine  of 
the  ischium,  where  it  narrows  considerably.  The  attachments  of 
the  sacro-sciatic  ligaments  to  the  sacrum  and  coccyx  are  more  or  less 
blended,  and  they  not  only  serve  to  connect  the  bones,  but  also,  from 
their  great  breadth,  contribute  to  diminish  the  lower  aperture  of  the 
pelvis. 

PUBIC  STM-  This  is  formed  by  the  union  of  the  pubic  bones, 

PHYSIS.  in  front,  by  means  of  an  interposed  piece  of  fibro- 

cartilage.  It  is  an  amphiarthrodial  articulation,  and  is  secured  by 
the  following  ligaments  : — 

The  anterior  pubic  ligament  consists  of  several  layers  of  irre- 
gular superficial  fibres  which  run  obliquely  and  decussate  with 
each  other,  and  of  deeper  fibres  which  pass  transversely  across  from 
one  bone  to  the  other,  and  are  connected  with  the  fibre-cartilage. 

The  posterior  pubic  ligament  consists  of  fibres,  less  distinct  than 
the  anterior,  which  connect  the  two  pubic  bones  posteriorly. 

The  superior  pubic  ligament  passes  across  the  upper  surface  of 
the  pubic  bones. 

The  subpubic  ligament  is  very  strong,  and  extends  between  the 
rami  of  the  pubic  bones,  beneath  the  fibro-cartilage  with  which  it 
is  blended ;  it  rounds  off  the  pubic  arch,  and  is  situated  between 
the  two  layers  of  the  triangular  ligament. 

The  intermediate  fibro-cartilage  is  composed  of  two  layers  of  car- 
tilage, each  attached  to  the  inner  border  of  the  body  of  the  os  pubis 
by  a  number  of  nipple-like  processes  fitting  in  to  corresponding 
depressions  on  the  bony  surface.  Between  these  cartilaginous 
plates  there  is  a  thick  stratum  of  fibrous  and  fibro-elastic  tissue. 
In  the  middle  line  at  the  upper  and  back  part  is  usually  a  smooth 
cavity  lined  with  epithelium.  The  cartilage  acts  as  a  buffer,  and 
breaks  the  force  of  shocks  passing  through  the  pelvic  arch. 

LIGAMENTS  OF  This  joint  is  secured  by  the  form  of  the  bones, 

THE  HIP-JOINT.  and  by  the  strength  of  the  powerful  muscles  which 
surround  it.  Although  an  enarthrodial  or  ball-and-socket  joint, 
its  range  of  motion  is  somewhat  limited ;  the  disposition  of  its 
ligaments  restricts  its  range  of  motion  to  those  directions  only 


HIP-JOINT.  697 

which    are   most    consistent  with   the  maintenance  of  the  erect 
attitude,  and  the  requirements  of  this  part  of  the  skeleton. 

The  ligaments  of  the  hip-joint  are — the  capsular,  the  ilio- 
femoral,  the  ligamentum  teres,  the  cotyloid,  and  the  transverse. 

CAPSULAB  The  capsular  ligament  is  attached  above  to  the 

LIGAMENT.  circumference  of  the  acetabulum,  a  little  external 

to  the  margin,  also  to  the  transverse  ligament,  and  by  a  few  fibres 
to  the  outer  margin  of  the  obturator  foramen ;  below,  to  the 
anterior  intertrochanteric  ridge  in  front ;  above,  to  the  root  of  the 
great  trochanter,  and  to  the  middle  of  the  neck  behind,  about  half 
an  inch  above  the  posterior  intertrpchanteric  ridge.  The  anterior 
and  upper  part  of  the  capsular  ligament  is  very  thick  and 
strong,  composed  chiefly  of  longitudinal  fibres  with  a  few  deeply 
seated  circular  fibres,  which  are  concealed  by  the  superficial  longi- 
tudinal bands..  The  posterior  aspect  of  the  capsular  ligament  is 
represented  by  a  few  sparsely  scattered  fibres.  The  front  part  of 
the  ligament  is  rendered  exceedingly  strong  by  several  accessory 
ligaments,  one  of  which,  called  the  ilio-femoral  ligament,  extends 
from  the  anterior  inferior  iliac  spine,  and  from  a  depression 
above  the  acetabulum,  and  then  divides  like  the  two  arms  of 
the  inverted  letter  ^  :  one,  the  inner  and  vertical,  passes  to  the  base 
of  the  lesser  trochanter  ;  the  outer,  to  the  upper  part  of  the  ante- 
rior intertrochanteric  line.  In  addition,  there  is  at  the  lower  and 
back  part  a  broad  ligament,  the  ischio-capsular  ligament,  whose 
fibres  extend  from  the  ischium  to  the  inner  part  of  the  joint,  close 
to  the  lesser  trochanter  ;  and  a  third  accessory  ligament,  the  pubo- 
femoral,  consists  of  the  thin  fibres  converging  from  the  ilio-pectineal 
eminence,  and  the  margin  of  the  obturator  foramen  to  the  front 
and  inner  part  of  the  capsular  ligament. 

The  ilio-femoral  ligament  is  very  strong,  and  serves  as  a  strap 
to  prevent  the  femur  being  extended  beyond  a  certain  point,  and 
limits  rotation  inwards  and  outwards. 

The  capsule  is  in  relation,  in  front,  with  the  iliacus  and  psoas 
muscles,  from  which  it  is  separated  by  a  synovial  bursa.  This 
bursa  occasionally  communicates  by  a  rounded  aperture  with  the 
synovial  cavity  of  the  hip-joint. 

Open  the  capsule  to  ascertain  its  great  thickness  in  front,  and 


'698 


LIGAMENTS    OF   THE    HIP-JOINT. 


its  strong  attachment  to  the  bones.  This  exposes  the  cotyloid 
ligament  and  the  ligamentum  teres. 

LIGAMENTUM  The  ligamentum  teres  is  exposed  by  drawing  the 

TEKES.  head  of  the  femur  out  of  the  socket.     This  lisa- 

O 

ment  is  somewhat  flat  and  triangular.  Its  base,  which  is  bifid,  is 
attached,  below,  to  the  borders  of  the  notch  in  the  acetabulum, 
where  it  becomes  continuous  with  the  transverse  ligament ;  its 


FIG.  162. 


Ilio-ltimbar  ligament  . 

Posterior  sacro-iliac 
ligament 


VERTICAL    SECTION    THROUGH    THE    HIP. 


apex,  to  the  fossa  in  the  head  of  the  femur.  To  prevent  pressure 
on  it,  and  to  allow  free  room  for  its  play,  there  is  a  gap  at  the 
bottom  of  the  acetabulum.  This  gap  is  not  crusted  with  cartilage 
like  the  rest  of  the  socket,  but  is  occupied  by  soft  fat.  The  liga- 
mentum teres  is  surrounded  by  the  synovial  membrane.  An  artery 
runs  up  with  it  to  the  head  of  the  femur.  It  is  a  branch  of  the 
obturator,  and  enters  the  acetabulum  through  the  notch  at  the 
lower  part. 


LIGAMENTS   OF  THE   HIP-JOINT.  699 

The  chief  use  of  the  ligamentum  teres  is  to  assist  in  steadying 
the  pelvis  on  the  thigh  in  the  erect  position.  In  this  position,  the 
ligament  is  vertical  and  quite  tight  (fig.  162);  it  therefore  pre- 
vents the  pelvis  from  rolling  towards  the  opposite  side,  or  the 
thigh  from  being  adducted  beyond  a  certain  point.  Another 
purpose  served  by  this  ligament  is  to  limit  rotation  of  the  thigh, 
both  inwards  and  outwards. 

COTYLOID  The  cotyloid   ligament   is   an   annular  piece  of 

LIGAMENT.  fibro-cartilage    which   is    attached   all  round  the 

margin  of  the  acetabulum.  Its  circumference  is  thicker  than  its 
free  margin,  which  is  very  thin,  so  that  on  a  transverse  section  the 
cartilage  is  triangular.  Both  its  surfaces  are  covered  with  synovial 
membrane,  and  its  attachment  to  the  margin  of  the  acetabulum  is 
effected  by  oblique  fibres  passing  from  without  inwards,  and  inter- 
lacing in  all  directions  at  an  acute  angle.  The  ligament  is  thicker 
above  and  behind  than  elsewhere  ;  it  thus  deepens  the  socket,  and 
embraces  the  head  of  the  femur  like  a  sucker.  It  extends  over 
the  notch  at  the  lower  part  of  the  acetabulum,  being  attached  to  a 

TRANSVERSE          ligament,  the  transverse,  which  passes  across  the 
LIGAMENT.  notch,  and  thus  converts  it  into  a  foramen.     Be- 

neath the  transverse  ligament  some  of  the  vessels  and  nerves  pass 
into  the  joint  to  supply  it. 

SYNOVIAL        .          The  synovial  membrane  extends  from  the  carti- 
MEMBBANE.  laginous  border  of  the  head,  round  the  neck  as  far  as 

the  attachment  of  the  capsular  ligament,  on  the  inner  surface  of  which 
it  is  reflected  as  far  as  the  margin  of  the  acetabulum.  Thence  it 
passes  over  the  superficial  surface  of  the  cotyloid  ligament,  curves 
round  its  inner  sharp  border  so  as  to  line  its  deeper  surface ;  it  then 
covers  the  osseous  surface  of  the  acetabulum,  and  is  finally  con- 
tinued as  a  tubular  sheath  over  the  ligamentum  teres  to  the  head  of 
the  femur.  The  synovial  membrane,  it  will  be  seen,  extends  down  to 
the  base  of  the  neck  of  the  femur  in  front,  but  only  two-thirds  behind. 
Between  the  bottom  of  the  acetabulum,  as  far  as  the  cotyloid  notch, 
and  the  synovial  membrane,  is  a  collection  of  fat  and  connective 
tissue  called  the  gland  of  Havers. 

The  ligaments  of  the  hip-joint  are  so  arranged  that,  when  we 
stand  '  at  ease/  the  pelvis  is  spontaneously  thrown  into  a  position 


700  MOVEMENTS   AT   THE   HIP-JOINT. 

in  which  its  range  of  motion  is  the  most  restricted ;  for  the  acces- 
sory ligaments  of  the  capsule  prevent  it  from  being  extended  beyond 
a  straight  line,  and  the  ligamentum  teres  prevents  its  rolling 
towards  the  opposite  side.  This  arrangement  economises  muscular 
force  in  balancing  the  trunk. 

The  atmospheric  pressure  is,  of  itself,  sufficient  to  keep  the 
limb  suspended  from  the  pelvis,  supposing  all  muscles  and  liga- 
ments to  be  divided.  When  fluid  is  effused  into  the  hip-joint,  the 
bones  are  no  longer  maintained  in  accurate  contact ;  and  it  some- 
times happens  that  the  head  of  the  femur  escapes  from  its  cavity, 
giving  rise  to  a  spontaneous  dislocation. 

The  movements  at  the  hip-joint  are  those  of  flexion,  extension, 
abduction,  adduction,  rotation,  and  circumduction. 

The  flexors  are,  the  ilio-psoas,  the  sartorius,  the  pectineus, 
the  adductor  longus  and  brevis,  the  gluteus  medius  and  mini- 
mus. 

The  extensors  are,  the  gluteus  maximus,  the  biceps,  semi- 
tendiiiosus,  and  the  semimembranosus. 

The  abductors  are,  the  upper  fibres  of  the  gluteus  maximus,  the 
gluteus  medius  and  minimus,  the  pyriformis,  and,  when  the  joint 
is  flexed,  the  obturator  internus  and  the  two  gemelli. 

The  adductors  are,  the  three  adductors,  the  pectineus,  the  gra- 
cilis,  and  the  sartorius. 

The  external  rotators  are,  the  ilio-psoas,  the  three  adductors,  the 
pectineus,  the  gluteus  maximus,  the  posterior  fibres  of  the  gluteus 
medius,  the  obturator  externus  and  internus,  the  gemelli,  the 
quadratus  femoris,  the  pyriformis,  and  the  sartorius. 

The  internal  rotators  are,  the  tensor  fasciae  femoris,  the  anterior 
fibres  of  the  gluteus  medius,  and  the  gluteus  minimus. 

Circumduction  is  effected  by  the  successive  action  of  the  different 
muscles  in  the  order  of  their  attachment  into  the  femur. 

The  muscles  in  immediate  relation,  with  the  hip-joint  are,  in 
front,  the  iliacus  and  psoas ;  on  the  outer  side,  the  reflected  tendon 
of  the  rectus,  the  gluteus  minimus ;  behind,  the  pyriformis,  gemel- 
lus  superior,  obturator  internus,  gemellus  inferior,  obturator  ex- 
ternus, and  quadratus  femoris ;  on  the  inner  side,  the  pectineus  and 
obturator  externus. 


LIGAMENTS   OF  THE   KNEE-JOINT.  701 

LIGAMENTS  OP  The  knee-joint  is  a  ginglymus  or  a  hinge-joint, 

THE  KNEE-JOINT.  and  the  bones  entering  into  its  formation  are, 
above,  the  condyles  of  the  femur,  below,  the  head  of  the  tibia,  and 
in  front,  the  patella.  Looking  at  the  skeleton,  one  would  suppose 
that  it  was  very  insecure ;  but  this  insecurity  is  only  apparent,  the 
joint  being  surrounded  by  powerful  ligaments,  and  a  thick  capsule 
formed  by  the  tendons  of  the  muscles  which  act  upon  it. 

First  examine  the  tendons  concerned  in  the  protection  of  the 
knee-joint.  In  front  is  the  ligameiitum  patellae ;  on  each  side  are 
the  tendons  of  the  vasti ;  on  the  outer  side,  in  addition,  it  is 
strengthened  by  the  strong  ilio-tibial  band ;  on  the  inner  side  there 
are  also  the  tendons  of  the  sartorius  and  gracilis ;  at  the  back  of 
the  joint  are  the  tendons  of  the  gastrocnemius  and  plantaris,  with 
the  semimembranosus  and  semitendicosus,  in  addition,  on  its  inner 
part,  and  the  tendons  of  the  popliteus  and  biceps  on  its  outer  part. 
It  deserves  to  be  mentioned  that  the  weakest  part  of  the  articulation 
is  near  the  tendon  of  the  popliteus,  which  arises  within  the  joint : 
here,  therefore,  pus  or  fluid  formed  in  the  popliteal  space  may  make 
its  way  into  the  joint,  or  vice  versa. 

The  ligaments  of  the  joint  may  be  divided  into  those  outside 
the  joint  and  those  within  it. 

Those  outside  the  joint  are,  the  ligamentum  patellae,  the  internal 
lateral,  the  two  external  lateral,  the  posterior  ligament,  and  the 
capsular  ligament. 

Those  within  the  joint  are,  the  two  crucial,  the  two  semilunar 
fibro-cartilages,  the  transverse,  the  coronary,  the  ligamenta  alaria, 
and  the  ligamentum  mucosum. 

LIGAMENTCM  The  ligamentum  patellce  is  a  strong,  thick,  liga- 

PATELL^E.  mentous  band,  about  three  inches  long,  extending 

from  the  lower  border  of  the  patella  to  the  tubercle  of  the  tibia. 
Beneath  it,  is  found  a  considerable  amount  of  fat,  which  separates 
the  ligament  from  the  joint,  and  in  fat  people  forms  a  prominent 
elastic  mass  on  each  side  of  the  ligament.  There  is  a  synovial  bursa 
between  the  ligamentum  patellae  and  the  tuberosity  of  the  tibia. 

INTERNAL  This  is  a  broad,  flat  band,  which  extends  from 

LATERAL  the  inner  condyle  of  the  femur  to  the  inner  tube- 

LIGAMENT.  rosity  and  the  inner  aspect  of  the  shaft  of  the 


702 


LIGAMENTS   OF   THE   KNEE-JOINT. 


FIG.  163. 


tibia  (fig.  163).  A  few  of  the  deeper  fibres  are  attached  to  the 
inner  semilunar  cartilage,  and  serve  to  keep  it  in  place.  The 
inferior  internal  articular  artery,  and  part  of  the  tendon  of  the 

semimembranosus,  pass  underneath  this 
ligament.  In  the  several  motions  of 
the  joint,  there  is  a  certain  amount  of 
friction  between  the  ligament  and  the 
head  of  the  tibia,  and  consequently  a 
small  bursa  is  interposed. 

EXTERNAL  The     long    external 

LATERAL  lateral   ligament   is    a 

LIGAMENTS.  strong     round     band 

which  extends  from  the  outer  condyle 
of  the  femur  to  the  outer  part  of  the 
head  of  the  fibula.  This  ligament  sepa- 
rates the  two  divisions  of  the  tendinous 
insertion  of  the  biceps.  Beneath  it 
pass  the  tendon  of  the  popliteus  and 
the  inferior  external  articular  artery. 

The  short  external  lateral  ligament  is 
situated  posterior  to,  and  runs  parallel 
with,  the  preceding  ligament ;  it  passes 
from  the  posterior  and  outer  part  of 
the  condyle  of  the  femur  to  the  tip  of 
the  styloid  process  of  the  fibula ;  the  tendon  of  the  popliteus  also 
lies  beneath  it. 

POSTERIOR  This,  which  is  generally  called  the  ligamentum 

LIGAMENT.  posticum  Winslowii,  covers  the  whole  of  the  pos- 

terior surface  of  the  knee-joint,  and  consists  of  two  portions — one 
formed  by  a  broad  flat  band  of  vertical  fibres  passing  from  the 
posterior  surface  of  the  femur  between  and  above  the  condyles  to 
the  posterior  part  of  the  tuberosity  of  the  tibia ;  the  other  con- 
sists of  an  oblique  tendinous  expansion  from  the  semimembranosus 
(p.  670),  which  passes  upwards  and  outwards  from  the  internal 
tuberosity  of  the  tibia  to  the  back  of  the  outer  condyle  of  the 
femur.  It  is  pierced  by  numerous  blood-vessels  to  supply  the 
knee-joint,  chiefly  by  the  azygos  artery  and  a  branch  from  the 


DIAGRAM  OF  THE  SEMILUNAR 
CARTILAGES  AND  LATERAL  LI- 
GAMENTS OF  THE  KNEE. 

1.  Internal  lateral  ligament. 
External         ditto. 


LIGAMENTS   OF   THE   KNEE-JOINT.  703 

obturator  nerve  (p.  643).  This  ligament  not  only  closes  and 
protects  the  joint  behind,  but  prevents  its  extension  beyond  the 
perpendicular. 

CAPSULAR  The  capsular  ligament   occupies   the   intervals 

LIGAMENT.  between  the  other  ligaments,  and  so  completes  the 

fibrous  investment  of  the  joint.  It  is  materially  strengthened  by 
fibrous  expansions  from  many  of  the  tendons  in  connection  with 
the  articulation. 

The  joint  should  be  opened  above  the  patella.  Observe  the 
great  extent  of  the  fold  which  the  synovial  membrane  forms  above 
this  bone.1  It  allows  the  free  play  of  the  bone  over  the  lower  part 
of  the  femur.  The  fold  extends  higher  above  the  inner  than  the 
outer  condyle,  which  accounts  for  the  form  of  the  swelling  produced 
by  effusion  into  the  joint. 

CRUCIAL  The  crucial  ligaments,  so  named  because  they 

LIGAMENTS.  cross  like  the  letter  X,  extend  from  the  mesial 

side  of  each  condyle  to  the  head  of  the  tibia. 

The  anterior  or  external  ligament,  the  smaller,  ascends  from  the 
inner  part  of  the  fossa  in  front  of  the  spine  of  the  tibia,  backwards 
and  outwards  to  the  inner  and  back  part  of  the  external  condyle. 
It  is  attached  to  the  tibia  close  to  the  anterior  termination  of  the 
external  semilunar  cartilage. 

The  posterior  or  internal  ligament,  best  seen  from  behind,  ex- 
tends from  the  back  of  the  fossa  behind  the  spine  of  the  tibia,  and 
from  the  posterior  termination  of  the  external  semilunar  cartilage, 
upwards,  forwards,  and  inwards  to  the  front  of  the  inner  condyle. 
The  direction  of  this  ligament  is  more  vertical  than  the  anterior 
one. 

j  T  Between  the  condyles  and  the  articular  surfaces 

LAB  OK  SEMI-  of  the  tibia  are  two  incomplete  rings  of  fibro- 

LUNAK  FIBKO-  cartilage,  shaped  like  the  letter  C.     They  serve 

CARTILAGES.  ^  <jeepen  tke  articular  surfaces  of  the  tibia ;  their 

mobility  and  flexibility  enable  them  to  adapt  themselves  to  the 
condyles  in  the  several  movements  of  the  joint ;  they  distribute 
pressure  over  a  greater  surface  and  break  shocks.  They  are 

1  In  performing  operations  near  the  knee,  the  joint  should  always  be  bent,  in 
order  to  draw  the  synovial  fold  as  much  as  possible  out  of  the  way. 


704  LIGAMENTS    OF   THE   KNEE-JOINT. 

thickest  at  the  circumference,  and  gradually  shelve  off  to  a  thin 
margin :  thus  they  fit  in  between  the  bones,  and  adapt  a  convex 
surface  to  a  flat  one,  as  shown  in  fig.  163.  Their  form  is  suited  to 
the  condyles,  the  inner  being  oval,  the  outer  circular,  and  the 
synovial  membrane  covers  both  surfaces  of  the  cartilages. 

The  external  semilunar  fibro-cartilage  is  nearly  a  circular  ring  of 
fibro-cartilage,  its  two  extremities  being  firmly  attached  to  the 
fossae,  one  in  front  of  and  the  other  behind  the  spine  of  the  tibia ; 
they  are  enclosed  by  the  two  extremities  of  the  internal  cartilage. 

On  its  outer  border  it  presents  a  groove  for  the  tendon  of  the 
popliteus ;  its  anterior  border  gives  off  a  transverse  fibrous  fascicu- 
lus, the  transverse  ligament,  which  passes  across  to  be  connected 
with  the  anterior  border  of  the  internal  cartilage.  The  anterior 
extremity  of  the  fibro-cartilage  is  connected  with  the  anterior 
crucial  ligament;  the  posterior  is  attached  partly  into  the  outer 
side  of  the  inner  tuberosity  in  front  and  behind  the  posterior  crucial 
ligament,  and  partly  into  the  anterior  crucial  ligament.1 

The  internal  semilunar  fibro-cartilage  forms  .about  two-thirds  of 
an  oval  ring,  and  is  narrower  in  front  than  behind.  Its  anterior 
extremity  is  pointed,  and  is  attached  to  the  tibia  internal  to  the 
anterior  crucial  ligament ;  its  posterior  extremity  to  the  pit  behind 
the  spine  immediately  in  front  of  the  posterior  crucial  ligament. 

The  transverse  ligament,  already  alluded  to,  is  a  thin  fibrous 
fasciculus  in  front  of  the  anterior  crucial  ligament,  and  connects 
the  anterior  borders  of  the  semilunar  fibro-cartilages. 

The  coronary  ligaments  are  two  ligaments  which  connect  the 
circumference  of  the  two  semilunar  cartilages  to  the  borders  of  the 
tibial  tuberosities.  The  external  ligament  is  the  weaker  of  the  two, 
so  that  the  external  cartilage  is  the  more  moveable. 

SYNOVIAL  The  synovial  membrane  is  very  extensive,  the 

MEMBKANE.  most  extensive  in  the  body.    It  lines  the  posterior 

surface  of  the  quadriceps  tendon,  and  the  aponeuroses  of  the  vasti, 

1  Of  the  two  cartilages  the  external  has  the  greater  freedom  of  motion,  because 
in  rotation  of  the  knee  the  outer  side  of  the  tibia  moves  more  than  the  inner. 
Consequently,  it  is  not  in  any  way  connected  to  the  external  lateral  ligament ;  so 
far  from  this,  it  is  separated  from  it  by  the  tendon  of  the  popliteus,  of  which  the 
play  is  facilitated  by  a  bursa  communicating  freely  with  the  joint.  For  this 
reason  the  external  cartilage  is  more  liable  to  dislocation  than  the  internal. 


THE   KNEE-JOINT.  705 

and  is  reflected  on  to  the  femur  a  variable  distance  above  the  in- 
crusting  cartilage ;  traced  from  the  femur,  we  find  that  it  lines  the 
inner  surface  of  the  capsular  ligament  as  far  as  the  circumference 
of  the  tibia ;  thence  it  is  reflected  over  the  upper  surfaces  of  the 
semilunar  cartilages,  round  their  inner  concave  margins  to  get  to 
their  under  surfaces,  from  which  the  membrane  passes  to  cover  the 
articular  surface  of  the  head  of  the  tibia.  It  forms  tubular  pro- 
longations round  the  crucial  ligaments,  and  below  the  patella  a 
slender  band  of  the  synovial  membrane  proceeds  backwards  to  the 
space  between  the  condyles,  and  is  called  the  ligamentum  mucosum. 
Two  lateral  folds,  extending  from  the  sides  of  the  mucous  ligament, 
pass  upwards  and  outwards  to  the  sides  of  the  patella ;  these  are 
termed  the  ligamenta  alaria.  These  are  not  true  ligaments,  but 
merely  remnants  of  the  partition  which,  in  the  early  stage  of  the 
joint's  growth,  divided  it  into  two  equar'portions. 

Outside  the  synovial  membrane  there  is  always  fat ;  especially 
under  the  ligamentum  patellae.  Its  use  is  to  fill  up  vacuities,  and 
to  mould  itself  to  the  several  movements  of  the  joint. 

The  movements  which  the  knee-joint  permits  are  those  of 
flexion  and  extension,  together  with  rotation  outwards  and  inwards. 
In  order  completely  to  master  its  various  movements,  the  student 
should  examine  the  movements  first  as  between  the  femur  and  the 
patella,  and  then  as  between  the  condyles  of  the  femur  and  the 
articular  surface  of  the  tibia  crowned  by  its  two  semilunar  carti- 
lages. 

The  articular  surface  of  the  patella  glides  upon  the  femoral 
condyles  in  extension  and  in  flexion.  If  this  surface  of  the  patella 
be  examined,  it  will  be  seen  that  each  lateral  facet  is  subdivided  by 
two  indistinct  transverse  ridges  into  three  very  shallow  transverse 
zones ;  each  of  these  zones  rests  upon  a  definite  part  of  the  trochlear 
surface  of  the  femur  in  the  different  stages  of  extension  or  flexion : 
thus,  in  extreme  extension,  the  lower  zones  of  the  patella  rest  upon 
the  upper  border  of  the  trochlear  surface ;  in  mid-flexion,  the 
middle  zones  alone  rest  on  the  femur ;  and  in  nearly  extreme  flexion, 
the  upper  zones  lie  in  the  lower  part  of  the  femoral  condyles.  In 
addition  to  the  six  shallow  facets  just  described,  there  is  a  seventh 
which  is  seen  on  the  inner  margin. 

z  z 


706  SUPERIOR   TIBIO-FIBULAR   ARTICULATION. 

The  respective  points  of  the  attachment  of  the  ligaments  are 
such  that,  when  the  joint  is  extended,  all  the  ligaments  are  tight, 
to  prevent   extension  beyond  the  perpendicular ;  thus  muscular 
force  is  economised.     But  when  the  joint  is  bent  the  ligaments  are 
relaxed,  enough  to  admit  a  slight  rotatory  movement  of  the  tibia. 
This  movement  is  more  free  outwards  than  inwards;  and  is 
effected,  not  by  rotation  of  the  tibia  on  its  own  axis,  but 
by  rotation  of  the  outer  head  round  the  inner.    Rotation 
outwards  is  produced  by  the  biceps ;  rotation  inwards 
by  the  popliteus  and  semimembranosus. 

The  crucial  ligaments,  though  placed  inside  the 
joint,  answer  the  same  purposes  as  the  coronoid  process 
and  the  olecranon  of  the  elbow.  They  make  the  tibia 
slide  properly  forwards  and  backwards.  In  extension, 
the  anterior  crucial  ligament  is  tight,  as  are  also  the 
lateral  ligaments :  in  flexion,  the  posterior  ligament 

LIGAMENTS  °  '  ,        ,.       .          n        . 

becomes  tight  and  consequently  limits  flexion.     They 

KNEE.        a^so  conjointly  limit  excessive  rotation.     They  not  only 
prevent  dislocation  in  front  or  behind,  but  they  pre- 
vent lateral  displacement,  since  they  cross  each  other  like  braces, 
as  shown  in  fig.  164. 

SUPERIOR  This  is  an  arthrodial  or  gliding  joint,  and  is 

TIBIO-FIBULAR  farmed  by  the  flat  oval  surfaces  of  the  upper  part 
ARTICULATION.  Of  fae  t^ia  and  fibula.  It  is  secured  by  an 
anterior  and  a  posterior  tibio-fibular  ligament. 

The  anterior  superior  tibio-fibular  ligament  is  a  strong  flat  liga- 
ment, whose  fibres  pass  obliquely  downwards  and  outwards  from  the 
external  tuberosity  of  the  tibia  to  the  head  of  the  fibula. 

The  posterior  superior  ligament  passes  in  the  same  direction  as 
the  anterior,  only  being  placed  behind  the  joint. 

The  synovial  membrane  occasionally  communicates  with  that  of 
the  knee-joint. 

INTEHOSSEOUS  The  contiguous  borders  of  the  tibia  and  fibula 

MEMBRANE.  are  connected  by  the  interosseous  membrane.    The 

purpose  of  it  is  to  afford  additional  surface  for  the  attachment  of 
muscles.  Its  fibres  pass  chiefly  downwards  and  outwards  from  the 
tibia  to  the  fibula,  but  a  few  fibres  cross  like  the  letter  X.  The 


ANKLE-JOINT.  707 

anterior  tibial  artery  comes  forwards  above  the  interosseous  mem- 
brane, through  an  oval  space  about  an  inch  below  the  head  of  the 
fibula.  Lower  down  there  is  an  aperture  for  the  anterior  peroneal 
artery.  It  is  moreover  pierced  here  and  there  by  small  blood- 
vessels. 

INFEBIOB  The  lower  extremities  of  the  tibia  and  fibula  are 

TIBIO-FIBULAB  firmly  connected,  for  it  is  essential  to  the  security 
ABTICULATION.  of  the  ankle-joint  that  there  should  be  little  or  no 
movement  between  the  two  bones. 

The  anterior  inferior  ligament  passes  between  the  adjacent 
borders  of  the  two  bones ;  it  is  narrow  above  but  broader  below, 
and  consists  of  oblique  fibres  which  pass  downwards  and  outwards. 

The  posterior  inferior  ligament  is  stronger  and  narrower  than 
the  anterior,  and  its  fibres  pass  horizontally  from  the  outer  mal- 
leolus  to  the  posterior  border  of  the  tibia,  above  the  articular 
surface. 

The  transverse  ligament  is  the  lower  part  of  the  preceding,  and 
may  be  usually  recognised  as  a  distinct  narrow  fasciculus. 

The  inferior  interosseous  ligament  consists  of  strong  short  fibres 
connecting  the  contiguous  surfaces  of  the  two  bones,  and  continuous 
above  with  the  interosseous  membrane. 

The  synovial  membrane  of  this  joint  is  an  extension  upwards  of 
that  of  the  ankle-joint. 

From  the  form  of  the  bones,  it  is  obvious  that 
ANKLE-JOINT.          ,,  ,  ,  ,  ,  .          .   . 

the  ankle  is  a  ginglymus  or  hinge-joint ;  conse- 
quently, its  security  depends  upon  the  great  strength  of  its  lateral 
ligaments.  The  hinge,  however,  is  not  so  perfect  but  that  it  admits 
of  a  slight  rotatory  motion,  of  which  the  centre  is  on  the  fibular 
side,  and  therefore  the  reverse  of  that  in  the  case  of  the  knee. 

The  ligaments  of  the  ankle-joint  comprise  the  anterior,  the 
internal  and  the  external  lateral  ligaments. 

The  anterior  ligament  is  a  thin  loose  membranous  ligament, 
attached  above  to  the  tibia,  and  below  to  the  astragalus  in  front  of 
their  articular  surfaces,  and  is  sufficiently  loose  to  permit  the 
necessary  range  of  motion. 

The  internal  lateral  ligament,  sometimes  called,  from  its  shape, 
deltoid,  is  exceedingly  thick  and  strong,  and  compensates  for  the 

z  z  2 


708 


LIGAMENTS   OF   THE   ANKLE-JOINT. 


comparative  shortness  of  the  internal  malleolus  (fig.  165).     The 
great  strength  of  it  is  proved  by  the  fact  that,  in  dislocation  of 


FIG.  165. 


1.  Plantar  fascia. 

2.  Calcaneo-scaphoid  ligament  which  supports  the  head  of  the  as%agalus. 

3.  Internal  lateral  ligament,  called  from  its  shape  deltoid. 


FIG.  166. 


DIAGRAM   OF   THE   EXTERNAL 
LATERAL   LIGAMENT. 

1.  Anterior  part. 

2.  Posterior  part. 

3.  Middle  part. 

4.  Interosseous  ligament  between 

the  astragalus  and  os  calcis. 


the  ankle  inwards,  the  summit  of  the 
malleolus  is  more  often  broken  off  than 
the  ligament  torn.  The  superficial 
portion  of  this  ligament  is  attached 
above  to  the  margin  of  the  internal 
malleolus,  and  passing  downwards  ra- 
diates to  be  inserted  into  the  scaphoid, 
the  inner  side  of  the  astragalus,  the 
sustentaculum  tali,  and  the  inferior 
calcaneo-scaphoid  ligament ;  the  deeper 
portion,  thick  and  strong,  passes  from 
the  tip  of  the  malleolus  to  the  astra- 
galus, close  to  its  articular  border. 

The  external  lateral  ligament  con- 
sists of  three  distinct  fasciculi,  an  an- 
terior, a  posterior,  and  a  middle  (fig. 
166).  The  anterior  fasciculus  passes 
from  the  front  of  the  tip  of  the  external 
malleolus,  nearly  horizontally  forwards 


LIGAMENTS   OF  THE   TARSUS.  709 

and  inwards  to  the  astragalus  in  front  of  its  malleolar  articular 
surface.  The  middle  fasciculus,  round  and  long,  passes  obliquely 
downwards  and  backwards  to  the  outer  surface  of  the  os  calcis. 
The  posterior  fasciculus  passes  from  the  posterior  part  of  the 
external  malleolus,  nearly  horizontally  outwards,  to  the  back  of 
the  astragalus  below  its  upper  articular  surface. 

Besides  flexion  and  extension,  the  ankle-joint  admits  of  a  slight 
lateral  movement,  only  permitted  in  the  extended  state,  for  the 
better  direction  of  our  steps.  In  adaptation  to  this  movement  the 
internal  malleolus  is  shorter  than  the  outer ;  it  is  not  so  tightly 
confined  by  its  ligaments,  and  its  articular  surface  is  part  of  a 
cylinder. 

Open  the  joint  to  see  that  the  breadth  of  the  articular  surfaces 
of  the  bones  is  greater  in  front  than  behind.  The  object  of  this  is 
to  render  the  astragalus  less  liable  to  be  dislocated  backwards. 
Whenever  this  happens,  the  astragalus  must  of  necessity  become 
firmly  locked  between  the  malleoli. 

LIGAMENTS  ^^e  astragalus  is  the  key-stone  of  the  arch  of 

CONNECTING  THE  the  foot,  and  supports  the  whole  weight  of  the 
BONES  OF  THE  body.  It  articulates  with  the  os  calcis  and  the  os 
TARSUS.  scaphoides  in  such  a  manner  as  to  permit  the 

abduction  and  adduction  of  the  foot,  so  useful  in  the  direction  of 
our  steps. 

ASTRAGALO-  The  astragalus  articulates  with  the  os  calcis  by 

CALCANEAN  two  surfaces  separated  by  the  deep  interosseous 

LIGAMENTS.  groove,  of  which  the  posterior  is  concave,  and  the 

anterior  convex.  The  articulations  are  strengthened  by  the  three 
ligaments,  the  external  and  the  posterior  astragalo-calcanean,  and 
the  interosseous. 

The  external  astragalo-calcanean  ligament  is  a  short,  quadrilateral 
fasciculus,  passing  from  the  outer  surface  of  the  astragalus,  in  front 
of  the  anterior  fasciculus  of  the  external  lateral  ligament,  almost 
directly  downwards  to  the  outer  surface  of  the  os  calcis. 

The  posterior  astragalo-calcanean  ligament  is  a  short  oblique 
band,  which  passes  from  the  posterior  border  of  the  astragalus  to 
the  upper  border  of  the  os  calcis. 

The  interosseous  ligament,  a  very  thick  strong  band  of  fibres 


710  CALCANEO-SCAPHOID   LIGAMENTS. 

which  descends  vertically  in  the  interosseous  canal,  and  is  the 
principal  bond  of  union  between  the  two  bones. 

ASTBAGALO-  The  anterior  surface  of  the  astragalus  is  broadly 

SCAPHOID  convex,  fitting  into    the  concave  surface   of  the 

LIGAMENT.  scaphoid  bone.     Superiorly  the  dorsal  surfaces  of 

the  two  bones  are  connected  by  a  broad  membranous  ligament,  astra- 
galo-scaphoid, which  passes  obliquely  across,  blending  externally 
with  the  external  calcaneo-scaphoid,  and  below  with  the  inferior 
calcaneo-scaphoid  ligament. 

CALCANEO-  ^n  tne  skeleton  the  head  of  the  astragalus  arti- 

SCAPHOID  culates  in  front  with  the  scaphoid,  but  the  lower 

LIGAMENTS.  part  of  it  is  unsupported.    This  interval  is  bridged 

over  by  a  very  strong  and  slightly  elastic  ligament,  which  extends 
from  the  os  calcis  to  the  scaphoid  (fig.  167)  ;  this  is  the  inferior 
calcaneo-scaphoid  ligament. 

The  inferior  calcaneo-scaphoid  ligament  is  thick  and  strong,  and 
passes  horizontally  forwards  and  inwards  from  the  sustentaculum 
tali  to  the  plantar  surface  of  the  scaphoid,  where  it  is  connected 
with  the  tendon  of  the  tibialis  posticus,  and,  superiorly,  with  the 
astragalo-scaphoid  ligament.  Thus  the  os  calcis,  scaphoid,  and 
this  ligament  form  a  complete  socket  for  the  head  of  the  astragalus ; 
it  is  this  joint,  chiefly,  which  permits  the  abduction  and  adduction 
of  the  foot.  In  chronic  disease  of  the  ankle-joint,  leading  to 
much  impairment  of  movement  at  the  joint,  the  motion  at  the 
astragalo-scaphoid  articulation  is  so  great  as  to  take  the  place  of 
the  ankle-joint.  This  ligament  being  slightly  elastic,  allows  the 
keystone  of  the  arch  (the  astragalus)  a  play,  which  is  of  great 
service  in  preventing  concussion  of  the  body.  Whenever  this 
ligament  yields,  the  head  of  the  astragalus  falls,  and  the  individual 
becomes  gradually  flat-footed.  In  this  yielding  of  the  ligament 
the  head  of  the  astragalus  not  only  falls,  but  becomes  also  rotated 
inwards. 

The  superior  calcaneo-scaphoid  ligament  is  short  and  triangular, 
lying  in  the  hollow  between  the  outer  part  of  the  astragalus  and 
the  os  calcis ;  it  passes  forwards  and  upwards  from  the  ridge  on 
the  anterior  and  outer  part  of  the  os  calcis  to  the  outer  side  of  the 
scaphoid. 


CALCANEO-CUBOID   LIGAMENTS. 


711 


CALCANEO-  The  os  calcis  articulates  with  the  os  cuboides 

CUBOID  AETICU-         nearly  on  a  line  with  the  joint  between  the  astra- 
LATION.  gains  and  the  scaphoid.     The  bones  are  connected 

together,  on  the  dorsum,  by  the  superior  and  internal  calcaneo- 


FIG.  167. 


cuboid  ligaments,  and  on  the  plantar  aspect  by 
the  long  and  short  calcaneo-cuboid  ligaments. 

The  superior  calcaneo-cuboid  ligament  is  a 
short  quadrilateral  band  of  fibres  passing  from 
the  upper  part  of  the  dorsal  aspect  of  the  os 
calcis  to  the  back  and  upper  part  of  the  os 
cuboides. 

The  internal  calcaneo-cuboid  ligament  con- 
nects the  front  part  of  the  ridge  of  the  os  calcis 
to  the  dorsal  and  inner  part  of  the  cuboid.  It  is 
sometimes  called  the  interosseous  ligament,  and 
is  closely  associated  with  the  superior  calcaneo- 
scaphoid  ligament. 

The  long  calcaneo-cuboid  ligament,  a  broad, 
long,  and  strong  band  of  ligamentous  fibres,  is 
the  more  superficial  of  the  two  inferior  calcaneo- 
cuboid  ligaments.  It  is  known  as  the  long 
plantar  ligament,  and  is  attached  to  the  under 
surface  of  the  os  calcis  in  front  of  the  tuber- 
osities,  as  far  as  the  anterior  tubercle  ;  it  passes 
forwards  to  the  plantar  aspect  of  the  cuboid,  being  attached  to  the 
ridge,  while  some  of  its  fibres  extend  to  the  bases  of  the  second, 
third,  and  fourth  metatarsal  bones,  and  complete  the  canal  for  the 
tendon  of  the  peroneus  longus. 

The  short  calcaneo-cuboid  ligament,  deeper  than  the  former,  is 
seen  somewhat  on  its  inner  aspect,  and  is  separated  from  it  by 
some  fat  and  connective  tissue.  It  is  very  broad,  and  passes  from 
the  front  of  the  tubercle  of  the  os  calcis,  for  about  an  inch  in  breadth, 
to  the  inner  and  posterior  surface  of  the  cuboid,  behind  the  ridge. 

The  articulations  between  the  cuboid  and  the  scaphoid  bones 
behind,  and  the  three  cuneiform  bones  in  front,  are  maintained  by 
dorsal,  plantar,  and  interosseous  ligaments. 

The  dorsal  and  the  plantar  ligaments  consist  of  parallel  fasciculi 


1.  Caleaneo-scaphoid 

ligament. 

2.  Calcaneo-cuboid 

ligament. 


712  SYNOVIAL   MEMBRANES   OF  THE   TARSUS. 

passing  between  the  contiguous  borders  of  the  respective  bones  on 
their  dorsal  and  plantar  aspects. 

The  interosseous  ligaments,  four  in  number,  are  composed  of 
transverse  fibres  (fig.  168)  connecting  the  rough  non-articular 
surfaces  of  the  contiguous  bones  :  the  first  one  is  between  the 
scaphoid  and  the  cuboid ;  the  second  connects  the  internal  and 
middle  cuneiform,  bones ;  the  third  is  between  the  middle  and 
external  cuneiform  bones;  and  the  fourth  between  the  external 
cuneiform  and  the  cuboid  bones. 

Though  there  is  very  little  motion  between  any  two  bones,  the 
collective  amount  is  such  that  the  foot  is  en- 

TTI  I  /*o 

abled  to  adapt  itself  accurately  to  the  ground  : 
pressure  is  more  equally  distributed,  and  con- 
sequently there  is  a  firmer  basis  for  the  support 
of  the  body.  Being  composed,  moreover,  of 
interosseous  ligaments  of  several  pieces,  each  of  which  possesses  a  certain 

the  wedge-bones.  .  ,  .  . 

elasticity,  the  toot  gains  a  general  springiness 
and  strength  which  could  not  have  resulted  from  a  single  bone. 

TAKSO-META-  The  tarsus  articulates  with  the  metatarsus  in 

TAESAL  JOINTS.  an  oblique  line  which  inclines  backwards  on  its 
outer  side.  This  line  is  interrupted  at  the  joint  of  the  middle 
cuneiform  bone  and  the  second  metatarsal  bone.  Here  there  is  a 
deep  recess,  so  that  the  base  of  this  metatarsal  bone  is  wedged  in 
between  the  internal  and  external  cuneiform  bones. 

These  joints  are  maintained  in  position,  above,  by  the  dorsal 
tarso-metatarsal  ligaments,  and,  below,  by  the  plantar  ligaments. 
Interosseous  ligaments  also  pass  between  the  wedge-bones,  main- 
taining them  in  their  normal  positions. 

SYNOVIAL  MEM-  Exclusive  of  the  ankle-joint  and  the  phalanges 
BRANES  OF  THE  of  the  toes,  the  bones  of  the  foot  are  provided  with 
TABSUS.  gix  Distinct  synovial  membranes ;  namely — 

1.  Between  the  posterior  articular  surface  of  the  os  calcis  and 
that  of  the  astragalus. 

2.  Between  the  head  of  the  astragalus  and  the  scaphoid,  and 
between  the  anterior  articular  surface   of  the   astragalus  and  os 
calcis. 

3.  Between  the  os  calcis  and  the  os  cuboides. 


JNTER-METATARSAL   ARTICULATIONS. 


713 


4.  Between  the  inner  cuneiform  bone  and  the  metatarsal  bone 
of  the  great  toe. 

5.  Between  the  scaphoid  and  the  three  cuneiform  bones,  and 
between  these  and  the  adjoining  bones  (the  great  toe  excepted). 

6.  Between  the  os  cuboides  and  the  fourth  and  fifth  metatarsal 
bones. 

The  tarso-metatarsal  articulations  are  arthrodial  joints. 


FIG.  169. 


DIAGRAM   OF   THE   ARTICULATIONS   OF    THE    TARSUS   AND   THE    TARSO-METATARSUS. 


1.  Posterior  calcaneo-astragaloid  ay  no  vial  cavity. 

2.  Calcaneo-scaphoid  synovial  cavity. 

3.  Calcaneo-cuboid  synovial  cavity. 

4.  Synovial  cavity  between  metatarsal  bone  of 

great  toe,  and  internal  cuneiform  bone. 


5.  Common  scapho-cuneiform,  intercuneiform, 

and    metatarso-cuneiform    synovial    ca- 
vity. 

6.  Cubo-metatarsal  synovial  cavity. 


INTER-META-  The  metatarsal  bones  are  connected  at  their 

TARSAL  ARTICU-  proximal  and  distal  ends  by  dorsal  and  plantar 
LATIONS.  ligaments ;  those  at  the  proximal  extremities  are 

very  strong,  and  are  supplemented  by  interosseous  ligaments, 
as  in  the  metacarpus  (p.  416).  The  movement  between  the 
proximal  ends  of  the  inter-metatarsal  articulations  is  arthrodial  or 
gliding. 

The  distal  extremities  of  the  metatarsal  bones  are  united  by  a 
transverse  metatarsal  ligament :  this  extends  from  the  great  toe  to 
the  little  toe  on  their  plantar  surfaces. 


714  METATARSO-PHALANGEAL   ARTICULATIONS. 

METATABSO-  These  are  connected  by  a  plantar  and  two 

PHALANGEAL  lateral  ligaments ;  the  dorsal  ligament  being 

AETICULATIONS.  formed  by  the  expansion  of  the  tendon  of  the 
extensor  longus  digitorum.  >  The  movements  which  take  place 
between  the  articulations  are  those  of  flexion,  extension,  abduction, 
and  adduction. 

PHALANGEAL  These  articulations  have  the  same  kind  of  liga- 

ARTICULATIONS.  ments  as  the  preceding,  and  the  movements  are 
also  nearly  identical. 


715 


DISSECTION  OF  THE  BRAIN. 

BEFORE  passing  on  to  the  examination  of  the  Jprain,  the  student 
MEMBRANES  should  study  the  arrangement,  the  structure,  and 

OF  THE  BRAIN.  foe  uses  of  the  three  membranes  by  which  the 
brain  is  enveloped. 

The  most  external  one,  the  dura  mater,  has  been  described 
(p.  8).  The  second,  or  intermediate  one,  is  a  serous  membrane, 
termed  the  arachnoid ;  the  third,  the  pia  mater,  is  a  vascular  layer, 
and  is  in  contact  with  the  encephalon. 

ARACHNOID  The  arachnoid  membrane,1  the  second   invest- 

MEMBRANE.  ment,  constitutes  the  smooth  polished  membrane 

covering  the  surface  of  the  brain,  and  is  exposed  after  the  removal 
of  the  dura  mater.  This  tunic  was  formerly  considered  by  anato- 
mists to  be  an  example  of  an  ordinary  serous  membrane,  and  was 
described  as  consisting  of  two  layers — an  external  or  parietal, 
which  lined  the  inner  surface  of  the  dura  mater,  and  an  internal  or 
visceral,  which  was  reflected  over  the  brain. 

It  is  now  regarded  as  consisting  of  one  layer  only — viz.,  the 
one  which  envelopes  the  brain  ;  the  under  aspect  of  the  dura  mater 
being  covered  only  with  a  layer  of  flattened  epithelium  cells.  The 
cavity  which  was  formerly  described  as  the  cavity  of  the  arach- 
noid, is  now  called  the  subdural  space,  and  contains  a  very  limited 
amount  of  fluid. 

The  arachnoid  membrane  is  a  colourless  and  transparent  layer, 
and  is  spread  uniformly  over  the  surface  of  the  brain,  from  which 
it  is  separated  by  the  pia  mater.  It  does  not,  like  the  pia  mater, 
dip  down  into  the  furrows  between  the  convolutions  of  the  brain, 
and  it  is  more  or  less  connected  with  the  pia  mater  by  delicate 
connective  tissue,  the  subarachnoid.  On  account  of  its  extreme 

a  spider's  web ;  elSos,  form. 


716  SUBARACHNOID   SPACES. 

tenuity,  and  its  close  adhesion  to  the  pia  mater,  the  two  membranes 
cannot  be  readily  separated  ;  but  there  are  places,  especially  at  the 
base  of  the  brain,  termed  subarachnoid  spaces,  where  the  arachnoid 
membrane  can  be  seen  distinct  from  the  subjacent  pia  mater.  The 
two  membranes  can  be  artificially  separated  by  blowing  air  beneath 
the  arachnoid  with  a  blow-pipe. 

SUBAEACHNOID  Wherever  the  arachnoid  membrane  is  separated 

SPACES  AND  FLUID,  from  the  pia  mater,  a  serous  fluid  (cerebro-spinal) 
intervenes,  contained  in  the  meshes  of  a  very  delicate  areolar  tissue. 
The  spaces  between  these  membranes  are  termed  subarachnoid,  and 
are  very  manifest  in  some  places.  For  instance,  there  is  one  well- 
marked  space  in  the  longitudinal  fissure,  where  the  arachnoid  does 
not  descend  to  the  bottom,  but  passes  across  the  edge  of  the  falx 
cerebri,  a  little  above  the  corpus  callosum.  At  the  base  of  the 
brain,  there  are  two  of  considerable  size  :  one,  the  anterior  sub- 
arachnoid  space,  is  situated  between  the  anterior  border  of  the  pons 
Varolii,  the  middle,  and  the  anterior  cerebral  lobes  ;  the  other,  the 
posterior  subarachnoid  space,  is  placed  between  the  cerebellar  hemi- 
spheres and  the  medulla  oblongata.  The  fluid  in  the  subarach- 
noid space  communicates  with  the  fluid  of  the  general  ventricular 
cavities  of  the  brain  through  an  aperture  (foramen  of  Magendie)  in 
the  fourth  ventricle,  close  to  its  lower  boundary ;  and  also  through 
an  opening,  on  each  side,  behind  the  glosso-pharyngeal  nerves. 
In  the  spinal  cord,  also,  there  is  a  considerable  interval  containing 
fluid  between  the  arachnoid  and  the  pia  mater.  The  purpose  of 
this  fluid  is,  not  only  to  fill  up  space,  as  fat  does  in  other  parts, 
but  mechanically  to  protect  the  nerve-centres  from  the  violent 
shocks  and  vibrations  to  which  they  would  otherwise  be  liable. 

The  brain,  therefore,  may  be  said  to  be  supported  in  a  fluid, 
which  insinuates  itself  into  all  the  inequalities  of  the  surface,  and 
surrounds  in  fluid  sheaths  all  the  nerves  as  far  as  the  foramina 
through  which  they  pass.  This  fluid  sometimes  escapes  through 
the  ear,  in  cases  of  fracture  through  the  base  of  the  skull,  involving 
the  meatus  auditorius  internus  and  the  petrous  portion  of  the 
temporal  bone. 

The  arachnoid  is  supplied  with  filaments  from  the  motor  root 
of  the  fifth,  the  facial,  and  the  spinal  accessory  nerves. 


PIA   MATER.  717 

The  cerebro-spinal  fluid  varies  in  amount  from  two  drachms  to 
two  ounces.  It  is  a  clear,  limpid  fluid,  slightly  alkaline,  contain- 
ing 98 -5  parts  of  water,  and  1*5  parts  of  solid  matter.  The  cere- 
bro-spinal  fluid  of  the  encephalon  and  that  of  the  spinal  cord 
communicate. 

This,  the  immediate  investing  membrane  of  the 
PIA  MATER 

brain,  is  extremely  vascular,  and  composed  of  a 

minute  network  of  blood-vessels  held  together  by  delicate  con- 
nective tissue.  It  covers  the  cerebral  surface,  and  dips  into  the 
fissures  between  the  convolutions,  forming  a  double  layer.  From 
its  internal  surface  numerous  vessels  pass  off  at  right  angles  into 
the  substance  of  the  brain.1  The  pia  mater  sends  a  prolongation 
through  the  transverse  fissure  into  the  lateral  and  third  ventricles, 
forming  the  velum  interpositum  and  the  choroid  plexuses,  and  also 
another  along  the  roof  of  the  fourth  ventricle,  forming  the  tela 
cJwroidea  inferior.  Upon  the  surface  of  the  cerebellum,  the  pia 
mater  is  thinner,  not  so  vascular,  and  only  sends  prolongations 
down  the  larger  sulci ;  on  the  pons  Varolii  and  the  medulla,  the 
membrane  is  more  fibrous  and  much  less  vascular  than  elsewhere. 

The  pia  mater  is  supplied  with  nerves  by  the  third,  fifth,  sixth, 
facial,  glosso-pharyngeal,  pneumogastric,  spinal -accessory,  and 
sympathetic  nerves,  which  chiefly  accompany  the  blood-vessels 
forming  the  pia  mater. 

ARTERIES  OP  The  brain  is  supplied  with  blood  by  the  two 

THE  BRAIN.  internal  carotid  and  the  two  vertebral  arteries. 

INTERNAL  This  artery  enters  the  skull  through  the  carotid 

CAROTID.  canal  in  the  temporal  bone,  and  ascends  very  tor- 

tuously, by  the  side  of  the  body  of  the  sphenoid,  along  the  inner 
wall  of  the  cavernous  sinus.  It  appears  on  the  inner  side  of  the 
anterior  clinoid  process,  and,  after  giving  off  the  ophthalmic,  divides 
into  an  anterior  and  middle  cerebral,  posterior  communicating  and 
anterior  choroid  arteries. 

a.  The  anterior  cerebral  artery  is  given  off  from  the  internal  carotid 
at  the  inner  end  of  the  fissure  of  Sylvius.  It  passes  forwards  and  in- 
wards to  reach  the  longitudinal  fissure  between  the  hemispheres,  curves 

1  Owing  to  these  vessels,  the  pia  mater,  when  placed  in  water,  presents  a  floccu- 
lent,  woolly  appearance,  and  hence  it  is  sometimes  called  tomentum  cerebri. 


718 


ARTERIES    OF   THE    BRAIN. 


round  the  front  part  of  the  corpus  callosum,  then  runs  backwards  over 
its  upper  surface  (under  the  name  of  the  artery  of  the  corpus  callosum), 
and  terminates  in  branches  which  anastomose  with  the  posterior  cerebral 
arteries."  The  anterior  cerebral  arteries  of  opposite  sides  run  side  by 
side,  and  supply  the  olfactory  lobes,  the  optic  nerves,  the  frontal  lobes, 

FIG.  170. 


Olfactory  bulb  .    .    . 


Second  pair  or  optic 
nerves 


Locus  pert oratus 
anticus. 


Tractus  options  .  . 
Crus  cerebri  .  .  . 
Third  pair  of  nerves 
Fourth  pair  of  nerves 
Fifth  pair  of  nerves  . 
Sixth  pair  of  nerves  . 


Pyramid 
Olive    . 


Vertebral  artery  .    . 
Anterior  spinal  a. 


Anterior  cerebral  a. 


Lamina  cinerea. 
Middle  cerebral  a. 
Tuber  cinereum. 
Mammillary  body. 
Locus  perforates 

medius. 
Posterior  cerebral  a. 

Superior  cerebellar  a» 
Pons  Varolii. 

Inferior  cerebellar  a. 
Seventh  )  pair  of 
Eighth.    J  nerves. 

Tenth      }P*"* 
Eleventh  Jnerves- 
.Twelfth  pair  of 
nerves. 

Cerebellum. 


the  anterior  perforated  spaces,  and  the  corpus  callosum.  At  the  base 
of  the  brain,  as  they  enter  the  longitudinal  fissure,  they  are  connected 
by  a  short  transverse  branch,  called  the  anterior  communicating  artery 
(fig.  170). 

6.  The  middle  cerebral  artery,  the  largest  branch  of  the  internal 


ARTERIES   OF  THE   BRAIN.  719 

carotid,  runs  outwards  deeply  within  the  fissure  of  Sylvius,  and  divides 
into  many  branches  distributed  to  the  anterior  and  middle  lobes.  Near 
its  origin  it  gives  off  a  number  of  small  arteries,  which  pierce  the  locus 
perforatus  anticus  to  supply  the  corpus  striatum. 

c.  The  posterior  cotiimunicating  artery,  unequal  in  size  usually  on 
the  two  sides,  proceeds  directly  backwards  to  join  the  posterior  cerebral ; 
thus  establishing  at  the  base  of  the  brain  the  free  arterial  inosculation 
called  the  circle  of  Willis. 

d.  The  anterior  choroid  artery,  a  small  branch  of  the  internal  carotid, 
arises  external  to  the  posterior  communicating  artery.     It  runs  back- 
wards, and  enters  the  fissure  at  the  bottom  of  the  middle  horn  of  the 
lateral  ventricle,  to  terminate  in  the  choroid  plexus  of  that  cavity.     It 
supplies,  in  addition,  the  hippocampus  major  and  the  corpus  fimbriatuin. 

VERTEBRAL  This  artery,  a  branch  of  the  subclavian  in  the 

AKTEKY.  first  part  of  its  course,  enters  the  foramen  in  the 

transverse  process  of  the  sixth  cervical  vertebra,  and  ascends  through 
the  transverse  processes  of  the  cervical  vertebrae.  It  then  winds 
backwards  along  the  arch  of  the  atlas,  and  enters  the  skull  through 
the  foramen  by  perforating  the  posterior  occipito-atlantal  ligament 
and  the  dura  mater.  It  then  curves  round  the  medulla  oblongata 
between  the  hypoglossal  nerve  and  the  anterior  root  of  the  first 
cervical  nerve.  At  the  lower  border  of  the  pons  Varolii  the  two 
arteries  unite  to  form  a  single  trunk — the  basilar — which  is  lodged 
in  the  groove  on  the  middle  of  the  pons,  and  bifurcates  at  its 
upper  border  into  the  posterior  cerebral  arteries. 

Each  vertebral  artery,  before  joining  its  fellow,  gives  off : — 

a.  Lateral  spinal  branches,  which  enter  the  spinal  canal,  to  supply 
the  spinal  cord  and  its  membranes,  and  the  bodies  of  the  cervical 
vertebrae. 

6.  Muscular  branches  to  the  deep  muscles  of  the  neck,  which  ana- 
stomose with  the  occipital  and  deep  cervical  arteries. 

c.  A  posterior  meningeal  branch,  distributed  to  the  posterior  fossa 
of  the  skull. 

d.  Anterior  and  posterior  spinal  arteries,  which  are   given  off  im- 
mediately before  the  vertebral  arteries  join  to  form  the  basilar,  run 
along  the  median  fissures  of  the  front  and  the  back  surfaces  of  the 
spinal  cord,  and  anastomose  with  the  spinal  branches  of  the  ascending 
cervical  arteries. 


720  ARTERIES   OF   THE   BRAIN. 

e.  The  jwsterior  inferior  cerebellar  artery,  sometimes  a  branch  of  the 
basilar,  but  more  frequently  of  the  vertebral,  passes  backwards  between 
the  spinal-accessory  and  the  pneumogastric  nerves,  to  the  under  surface 
of  the  cerebellum.  It  divides  into  two  branches  :  an  outer,  which 
ramifies  on  the  lower  surface  of  the  cerebellum  as1  far  as  its  outer  border  ; 
and  an  inner,  which  passes  to  the  vallecula  between  the  two  hemispheres, 
and  supplies  branches  to  the  fourth  ventricle. 

The  basilar  artery,  formed  by  the  junction  of  the  two  vertebral, 
in  its  course  along  the  pons,  gives  off  on  each  side  : — 

a.  Transverse  branches  which  pass  outwards  on  the  pons  :  one,  the 
internal  auditory,  enters  the  meatus  auditorius  internus  with  the  audi- 
tory nerve,  to  be  distributed  to  the  internal  ear  on  each  side. 

b.  The  anterior  inferior  cerebellar,  which  supplies  the  front  part  of 
the  lower  surface  of  the  cerebellum,  and  anastomoses  with  the  other 
cerebellar  arteries. 

c.  The  superior  cerebellar  arteries,  given  off  near  the  bifurcation  of 
the  basilar,  are  distributed  to  the  upper  surface  of  the  cerebellum,  and 
anastomose  with  the  inferior  cerebellar  ;  branches  are  supplied  to  the 
pineal  body,  the  valve  of  Vieussens,  and  the  velum  interpositum. 

d.  The  posterior  cerebral  arteries  are  the  two  terminal  branches  into 
which  the  basilar  artery  divides.     They  run  outwards  and  backwards, 
in  front  of  the  third  cranial  nerve,  and  wind  round  the  crura  cerebri  to 
the  under  surface  of  the  posterior  cerebral  lobes,  where  they  divide  into 
numerous  branches  for  the  supply  of  the  brain,  anastomosing  with  the 
anterior  and  middle  cerebral  arteries.     Shortly  after  their  origins  they 
receive  the  two  posterior  communicating  arteries  from  the   internal 
carotids.     Each  gives  off  small  branches  to  the  posterior  perforated 
space,  and  also  the  small  posterior  choroid  artery,  which,  passing  beneath 
the  posterior  border  of  the  corpus  callosum  and  fornix,  is  distributed  to 
the  velum  interpositum  and  choroid  plexus. 

CIECLE  OF  This  important  arterial  inosculation  (fig.   170) 

WILLIS.  takes  place  between  the  branches  of  the  two  in- 

ternal carotid  and  the  two  vertebral  arteries.  It  is  formed,  laterally, 
by  the  two  anterior  cerebral,  the  two  internal  carotid,  and  the  two 
posterior  communicating  arteries ;  in  front,  it  is  completed  by  the 
anterior  communicating  artery ;  behind,  by  the  two  posterior  cere- 
bral. The  tortuosity  of  the  large  arteries  before  they  enter  the 


THE   CEREBRAL   CIRCULATION.  721 

brain  serves  to  mitigate  the  force  of  the  heart's  action ;  and  the 
circle  of  Willis  provides  a  free  supply  of  blood  from  other  vessels, 
in  case  any  accidental  circumstance  should  stop  the  flow  of  blood 
through  any  of  the  more  direct  channels.1 

PECULIARITIES  Besides  the  circle  of  Willis,  there  are  other 

OF  THE  CEREBRAL  peculiarities  relating  to  the  circulation  of  the 
CIRCULATION.  blood  in  the  brain :  namely,  the  length  and  tor- 

tuosity of  the  four  great  arteries  as  they  enter  the  skull ;  their 
passage  through  tortuous  bony  canals ;  the  spreading  of  their  rami- 
fications in  a  very  delicate  membrane,  the  pia  mater,  before  they 
enter  the  substance  of  the  brain  ;  the  minuteness  of  the  capillaries, 
and  the  extreme  thinness  of  their  walls;  the  formation  of  the 
venous  sinuses  (p.  10),  which  do  not  accompany 'the  arteries;  the 
chordae  Willisii  in  the  superior  longitudinal  sinus ;  the  absence  of 
valves  in  the  sinuses;  and  the  confluence  of  no  less  than  six 
sinuses,  forming  the  torcular  Herophili,  at  the  internal  occipital 
protuberance. 

GENERAL  DIVI-  F-"^ie  mass  of  nervous  substance  contained  within 
SIGN  OF  THE  the  cranial  cavity,  comprised  under  the  common 

BRAIN,  term  brain  (encephalon),  is  divided  into  four  parts. 

The  cerebrum  forms  the  largest  portion,  and  occupies  the  whole  of 
the  upper  part  of  the  cranial  cavity ;  its  base  resting  on  the  an- 
terior and  middle  fossae  and  the  tentorium  cerebelli.  It  is  con- 
nected with  the  pons  Varolii  by  two  white  nerve-masses,  the  crura 
cerebri,  and  with  the  cerebellum  by  two  white  cords,  the  crura 
cerebelli.  The  cerebellum,  or  smaller  brain,  occupies  the  space 
between  the  tentorium  cerebelli  and  the  inferior  occipital  fossae. 
The  pons  Varolii  is  the  quadrilateral  mass  of  white  fibres  which 
rests  upon  the  basilar  process  of  the  occipital  bone.  The  medulla 

1  In  many  of  the  long-necked  herbivorous  quadrupeds  a  provision  has  been  made 
in  the  disposition  of  the  internal  carotid  arteries,  for  the  purpose  of  equalising  the 
force  of  the  blood  supplied  to  the  brain.  The  arteries,  as  they  enter  the  skull,  divide 
into  several  branches,  which  again  unite  and  form  a  remarkable  network  of 
arteries,  called  by  Galen,  who  first  described  it,  the  '  rete  mirabile.'  The  object  of 
this  evidently  is  to  moderate  the  rapidity  with  which  the  blood  would  otherwise 
enter  the  cranium  in  the  different  positions  of  the  head,  and  thus  preserve  the 
brain  from  those  sudden  influxions  to  which  it  would  under  other  circumstances 
be  continually  exposed. 

3A 


722  MEDULLA   OBLONGATA. 

oblongata  is  the  portion  below  the  pons,  which  is  continuous  below 
with  the  spinal  cord  and  rests  upon  the  lower  part  of  the  basilar 
process  of  the  occipital  bone. 

The  result  of  a  large  number  of  observations  shows  that  the 
weight  of  the  brain  averages  in  males  49^  oz.,  and  in  females  about 
44  oz. ;  although  it  has  been  known  to  weigh  as  much  as  64  oz., 
as  in  the  case  of  Cuvier's  brain,  and  as  little  as  23  oz.,  in  the  case 
of  an  idiot's  brain. 

The  following  are  the  weights  of  the  various  portions  of  the 
encephalon  which  have  been  carefully  collated  by  Dr.  J.  Reid.1 

MALE  FEMALE 

oz.    drs.  oz.  drs. 

Cerebrum 43  15J  38  12 

Cerebellum 54  4  12£ 

Pons  and  medulla  oblongata  .        .        .          15|  1    OJ 

Total    50  3£  44    8J 

The  average  specific  gravity  of  the  brain  is  about  1036  :  that 
of  the  white  matter  being  1040,  and  that  of  the  grey  1034. 

The  relative  proportion  of  the  amount  of  white  to  grey  matter 
is,  64  per  cent,  of  white  substance  to  36  per  cent,  of  grey  matter. 

The  weight  of  the  encephalon  varies  greatly  in  different  sub- 
jects, and  although  its  weight  seems  to  bear  some  proportionate 
relation  to  the  intellectual  power,  yet  in  many  instances  there 
appears  to  be  no  such  definite  relation. 

The  brain  weight  gradually  increases  up  to  the  age  of  forty, 
when  it  attains  its  maximum ;  after  this  period  the  weight  decreases 
at  the  rate  of  one  ounce  for  every  additional  ten  years  of  life. 


MEDULLA  OBLONGATA. 

The  medulla  oblongata  is  that  part  of  the  cerebro-spinal  axis 
which  is  placed  below  the  pons  Varolii,  and  is  continuous  with  the 
spinal  cord  on  a  level  with  the  upper  border  of  the  atlas.  It  is 
slightly  pyramidal  in  shape,  with  the  broad  part  above.  It  lies  on 
the  basilar  groove  of  the  occipital  bone,  and  descends  obliquely 

1  Reid,  London  and  Edinburgh  Monthly  Journal  of  Medical  Science,  April 
1843. 


MEDULLA   OBLONGATA. 


723 


backwards  through  the  foramen  magnum.  Its  posterior  surface  is 
received  into  the  fossa  (vallecula)  between  the  hemispheres  of  the 
cerebellum.  It  is  about  an  inch  and  a  quarter  in  length,  three 
quarters  of  an  inch  at  its  broadest  part,  and  half  an  inch  in  thick- 
ness. 

In  front  and  behind,  the  medulla  is  marked  by  a  median 
fissure,  the  anterior  and  posterior  median  fissures,  which  are  the 
continuations  of  the  median  fissures  of  the  spinal  cord.  The 
anterior  ends,  below  the  pons  Varolii,  in  a  cul-de-sac,  termed  the 
foramen  ccecum,  and  is  occupied  by  a  process  of  pia  mater.  The 

FIG.  171. 


1.  Gasserian  ganglion. 

2.  Motor   root   of    the 

fifth  n. 

3.  Third  n. 

4.  Arciform  fibres. 


C.  Crus  cerebri. 
P.  V.  Pons  Varolii. 
P.  Anterior  pyramid. 
O.  Olive. 

B.  Bestiform  tract  or 
body. 


5.  Sensitive  root  of  the 

fifth  n. 

6.  Sixth  n. 

7.  The     seventh     and 

eighth  nerves. 

8.  The  ninth,  tenth,  and 

eleventh  nerves. 

9.  Twelfth  or  hypoglos- 

saln. 


DIAGRAM   OF   THE   FRONT   SURFACE   OF   THE   MEDULLA   OBLONGATA. 

posterior  runs  along  the  floor  of  the  fourth  ventricle  as  a  shallow 
median  groove. 

The  surface  of  the  medulla  is  marked  out  on  each  side  into 
four  longitudinal  columns,  which  receive  the  following  names, 
from  before  backwards  :  the  anterior  pyramids,  the  lateral  tracts  and 
the  olivary  bodies,  the  restiform  bodies,  and  the  posterior  pyramids. 

The  anterior  pyramids  are  two  columns  of  white  matter,  narrow 

3  A  2 


724  MEDULLA    OBLONGATA. 

below,  but  increasing  gradually  in  breadth  as  they  ascend  towards 
the  pons.  At  this  part  they  become  constricted,  and  may  be  traced 
through  the  pons  into  the  crura  cerebri.  The  fibres  of  which  they 
are  in  the  main  composed  are  derived  from  the  anterior  columns  of 
the  spinal  cord,  and  consist  therefore  of  motor  fibres.  On  separating 
the  pyramids  about  an  inch  below  the  pons,  bundles  of  nerves  are 
seen  decussating  across  the  anterior  fissure  (fig.  171).  This  de- 
cussation,  which  consists  of  three  or  four  bundles  on  each  side, 
involves  only  the  inner  fibres  of  the  pyramid;  the  outer  fibres 
ascend  through  the  pons  without  crossing.  The  decussating  fibres 
are  the  continuations  upwards  of  the  deep  fibres  of  the  lateral 
pyramidal  tract  and  the  lateral  columns  of  the  cord,  which  here 
come  forwards  to  the  surface,  and  push  aside  the  anterior  pyramids. 
Thus  it  will  be  seen  that  the  thickness  of  the  anterior  pyramids  is 
mainly  due  to  these  decussating  bundles ;  that  the  fibres  on  the 
outer  side  of  the  pyramids  are  those  continued  upwards  from  the 
anterior  column  of  the  cord ;  and  that  the  inner  part  is  made  up 
of  the  fibres  of  the  lateral  tract  of  the  opposite  side. 

This  decussation  explains  the  phenomenon  of  cross  paralysis, 
i.e.  when  one  side  of  the  brain  is  injured,  the  loss  o£  motion  is 
manifested  on  the  opposite  side  of  the  body.1 

The  olivary  bodies  are  the  two  oval  eminences  situated  on  the 
outer  side  of  the  upper  part  of  the  anterior  pyramids,  from  which 
they  are  separated  by  a  shallow  depression.  They  do  not  ascend 
quite  as  high  as  the  pons,  for  there  is  a  deep  groove  between  them. 
They  consist  externally  of  white  matter ;  and  at  their  lower  part, 
some  white  fibres  maybe  observed  arching  round  from  the  anterior 
median  fissure,  constituting  the  arciform  fibres  of  Rolando.  In  the 
groove  between  the  anterior  pyramids  and  these  bodies  are  seen 
the  fasciculi  of  the  hypoglossal  nerve  emerging  from  the  medulla, 
and  in  the  groove  behind  the  olive  emerge  the  roots  of  the  glosso- 
pharyngeal,  the  pneumogastric,  and  spinal-accessory  nerves. 

The  lateral  tracts,  situated  on  the  outer  side  of  the  anterior 
pyramids,  are  the  continuations  upwards  of  the  lateral  columns  of 

1  The  phenomenon  of  cross  paralysis  of  sensation  is  explained  by  the  fact, 
made  out  by  Brown-S6quard,  that  the  paths  of  sensory  impressions  cross  each 
other  in  the  grey  matter  of  the  cord. 


MEDULLA   OBLONGATA. 


725 


the  spinal  cord.  As  described,  the  greater  number  of  their  fibres 
pass  across  the  anterior  median  fissure  to  the  opposite  anterior 
pyramid ;  but  some  ascend  as  far  as  the  lower  border  of  the  olivary 
body,  where  they  divide,  a  few  passing  in  front  of,  but  the  larger 
part  passing  behind  this  body  in  their  course  to  the  brain. 

The  restiform1  bodies  are  the  broadest  and  thickest  of  the 
columns  of  the  medulla.  They  are  situated  to  the  outer  side  and 
behind  the  lateral  tracts  and  the  olivary  bodies.  They  are  the 
continuations  upwards  of  the  posterior  columns  of  the  spinal  cord, 
and  as  they  ascend,  they  diverge  and  pass  into  the  cerebellum, 

FIG.  172. 


DIAGRAM    OF    THE    FOURTH    VENTRICLE    AND    RESTIFORM    BODIES. 

1.  Thalamus  options.  4.  Processus  a  cerebello  ad  testes. 

2.  Nates  and  testes,  or  corpora  quadrigemina.    5.  Restiform  bodies  diverging. 

3.  Origin  of  fourth  nerve.  6.  Origins  of  eighth  or  auditory  nerve. 

constituting  its  inferior  peduncles  (fig.  172).  Owing  to  this 
divergence,  the  grey  matter  of  the  medulla  is  exposed,  so  that  the 
floor  of  the  fourth  ventricle  (of  which  the  restiform  bodies  and  the 
posterior  pyramids  assist  in  forming  the  lateral  boundaries)  is 
mainly  composed  of  grey  matter.  Near  the  commencement  of  each 

1  From  restis,  a  rope. 


726  MEDULLA   OBLONGATA. 

restiform  body  there  is  easily  recognisable  an  eminence  interposed 
between  the  restiform  body  and  the  groove  which  separates  it  from 
the  lateral  tract;  this  eminence,  narrow  at  first,  is  known  as  the 
funiculus  of  Rolando,  but  it  soon  enlarges  to  form  a  considerable 
prominence,  .called  the  tubercle  of  Rolando.  The  restiform  body  on 
a  transverse  section  is  wedge-shaped,  and  hence  it  is  sometimes 
called  the  funiculus  cuneatus ;  near  the  level  where  the  two  bodies 
diverge,  each  presents  an  enlargement,  known  as  the  cuneate  tuber- 
cle. The  restiform  bodies  consist,  as  before  said,  of  white  fibres 
derived  from  the  posterior  and  lateral  columns  of  the  cord ;  in  its 
interior  is  some  grey  matter  continuous  with  that  in  the  posterior 
part  of  the  cord. 

The  posterior  pyramids  (funiculi  graciles)  are  two  slender  white 
columns  on  each  side  of  the  posterior  median  fissure,  and  are  the 
continuations  upwards  of  the  posterior  median  columns  of  the 
spinal  cord.  Ascending,  they  diverge  and  thus  form  the  apex  of 
the  fourth  ventricle.  At  their  point  of  separation  the  posterior 
pyramids  enlarge,  and  form  the  clava ;  after  which  they  rapidly 
taper  off,  and  run  up  on  the  inner  side  of  the  restiform  bodies, 
which  however  they  soon  leave,  and  are  continued  upwards  into 
the  cerebrum,  along  the  floor  of  the  fourth  ventricle. 

Emerging  from  the  anterior  median  fissure  may  be  noticed 
some  superficial  transverse  white  fibres,  which  cross  over  the 
anterior  pyramids  and  the  lower  extremity  of  the  olivary  bodies ; 
these  are  known  as  the  arciform  fibres  of  Rolando  (fig.  171),  and 
they  pass  upwards  to  join  the  restiform  body.  They  are  probably 
connected  with  white  fibres  which  run  horizontally,  constituting 
an  imperfect  septum  between  the  two  halves  of  the  medulla,  and 
may  be  seen  when  a  longitudinal  section  is  carefully  made  through 
its  middle.  The  majority  of  these  septal  fibres  enter  the  olivary 
bodies,  and  then  emerging  through  the  grey  matter  of  the  corpus 
dentatum,  become  continuous  with  the  fibres  of  the  restiform  bodies 
and  lateral  tracts  ;  others  pass  out  from  the  posterior  fissure  and 
wind  round  the  restiform  bodies.  These  latter  fibres  are  the  trans- 
verse strice,  seen  on  the  floor  of  the  fourth  ventricle,  some  of  which 
form  the  roots  of  the  auditory  nerves. 

The  lower  portion  of  the  fourth  ventricle  can  now  be   seen, 


STRUCTURE   OF   THE   MEDULLA.  727 

bounded  laterally  by  the  diverging  posterior  pyramids  and  the 
restiform  bodies,  the  floor  being  formed  by  the  grey  matter  of  the 
medulla.  As  only  part,  however,  can  be  examined  in  the  present 
stage,  the  full  consideration  of  the  fourth  ventricle  is  deferred  to  a 
later  stage  in  the  dissection  of  the  brain  (p.  771). 

MINUTE  STKUC-          These  are  among  the  most  complicated  parts  of 

TUBE  OF  THE  the  central  nervous  system.     They  contain  white 

MEDULLA  and  grey  matter  intermixed.     The  white  matter 

consists,  in  part,  of  the  continuation  upwards  of 

the  longitudinal  fibres  of  the  cord  ;  in  part,  of  horizontal  fibres. 

ANTERIOB  The  anterior  columns  of  the  cord  (fig.  173), 

PYBAMIDS.  having  reached  the  lower  part  of  the  medulla 

oblongata,  are  not  continued  straight  through  it,  but  diverge  from 
each  other,  being  reinforced  by  the  deep  fibres  of  the  lateral 
columns,  which  here  cross  over  and  form  the  decussation  of  the 
anterior  pyramids.  In  their  further  progress  the  fibres  of  the 
anterior  columns  are  arranged  thus :  some  of  them  run  up  and 
form  the  outer  portion  of  their  own  pyramid ;  some  of  them  pass 
deeply  beneath  the  pyramid  to  constitute  the  longitudinal  fibres  of 
the  reticularis  alba ;  these  fibres  are  continued  upwards  into  the 
cerebrum :  some  ascend  beneath  the  olive  to  join  the  restiform 
body  and  thence  to  the  cerebellum ;  another  and  larger  fasciculus 
passes  upwards  and,  after  embracing  the  olive,  reunites  to  form  a 
single  bundle ;  this,  joined  by  fibres  (olivary  fasciculus)  from  the 
olive,  ascends  under  the  name  of  the  fillet  of  Reil,  over  the  superior 
crus  of  the  cerebellum,  to  pass  to  the  corpora  quadrigemina  and  the 
cerebral  hemispheres  (fig.  173). 

LATEBAI.  The  lateral  columns  on  reaching  the  medulla 

TKACTS.  are  disposed  of  in  three  ways,  as  follows  : — some 

of  its  fibres,  the  internal,  come  forward  between  the  diverging 
anterior  columns,  decussate  in  the  middle  line,  and  form  part  of 
the  pyramid  of  the  opposite  side  ;  others,  the  external,  ascend 
with  the  restiform  body  (or  tract)  to  the  cerebellum ;  a  third  set, 
the  middle,  ascend  beneath  the  olivary  body,  along  the  floor  of 
the  fourth  ventricle  (concealed  by  its  superficial  grey  matter)  as 
the  fasciculus  teres,  and  are  continued  along  the  upper  part  of  the 
crus  cerebri  into  the  corpora  quadrigemina  and  optic  thalamus. 


728 


STRUCTURE   OF  THE   MEDULLA. 


OLIVARY  The  olivary  bodies  are  composed  externally  of 

BODIES.  white  matter ;  but  if  a  transverse  section  be  made 

into  them,  their  interior  presents  an  undulating  line  of  yellowish- 
brown  colour,  called,  from  its  zigzag  shape,  the  corpus  dentatum  or 
the  nucleus  of  the  olivary  body.  It  forms  an  interrupted  circle, 
incomplete  at  its  upper  and  inner  side,  so  that  it  allows  the 
entrance  of  a  bundle  of  white  fibres — olivary  peduncle — from  the 
medulla  behind  the  anterior  pyramid.  The  peduncular  fibres  pass 
in  various  directions :  some  pass  into  the  grey  matter ;  some  pass 
through  it  and  join  the  restiform  body,  under  the  name  of  the 
internal  arcuate  fibres ;  and  some  passing  between  the  fibres  over 
the  olivary  body,  come  to  the  surface  and  curve  round  it,  forming 
the  external  arcuate  fibres.  Two  other  isolated  grey  nuclei  may 
be  recognised  in  this  transverse  section,  one  on  the  inner  side 

FIG.  173. 


1.  Anterior  column. 

2.  Lateral  column. 

3.  Posterior  column. 

4.  Posterior  median  column 

of  the  spinal  cord. 

5.  Anterior  pyramid. 

6.  Eestiform  body. 


7.  Posterior  pyramid. 

8.  Fasciculus  teres. 

9.  Inferior  cms  of  the  cere- 

bellum. 

10.  To    the    corpora    quadri- 

gemina. 

11.  Crus  cerebri. 


DIAGRAM   OF   THE    COURSE    OF   THE    FIBRES   THROUGH    THE    MEDULLA 
OBLONGATA. 

of,  and  the  other  behind  the  corpus  dentatum :  these,  called  the 
accessor?/  olivary  nuclei,  are  linear  in  shape,  and  are  about  a  line 
in  length;  the  root-fibres  of  the  hypoglossal  nerve  pass  between 
the  inner  nucleus  and  the  corpus  dentatum,  to  emerge  between 
the  anterior  pyramid  and  the  olivary  body. 

EESTIFORM  The  posterior  columns  are  continued  upwards 

BODIES.  under  the  name  of  the  restiform  bodies  along  the 


GEEY  MATTER  OF  THE  MEDULLA.  729 

back  of  the  medulla.  At  the  apex  of  the  fourth  ventricle  they 
diverge  from  each  other  and  receive  bundles  of  accessory  fibres 
from  the  anterior  pyramids  and  the  lateral  tracts,  and  are  con- 
tinued partly  into  the  cerebellum,  forming  its  inferior  crura,  and 
partly  as  the  fasciculi  tereies  along  the  floor  of  the  fourth  ventricle 
into  the  cerebrum. 

POSTERIOR  The  posterior  pyramids  are  the  continuations 

PYRAMIDS.  upwards  of  the  posterior  median  columns  of  the 

spinal  cord ;  and,  like  the  restiform  body,  each  divides  into  two 
fasciculi,  one  of  which  ascends  and  helps  to  form  the  inferior  crus 
of  the  cerebellum,  the  other  runs  up  with  the  fasciculus  teres. 

SEPTUM  OR  The  horizontal  fibres  in  the  medulla  oblongata 

BAPH&  were   first    accurately  described   by  Stilling  and 

Rolando,  and  subsequently  by  Clarke  and  others.  Some  of  them  form 
a  septum  and  divide  the  medulla  oblongata  into  symmetrical  halves ; 
some  run  longitudinally  and  others  obliquely.  The  fibres  which 
run  from  the  dorsal  to  the  ventral  surface  of  the  medulla — fibres 
rectos, — pass  outwards,  in  front,  from  the  anterior  median  fissure, 
and  are  continuous  with  the  superficial  arched  fibres  of  Rolando ; 
while,  behind,  they  are  continuous  with  the  fibres  of  the  fasciculi 
graciles  and  their  grey  nuclei.  The  longitudinal  fibres  run  vertically 
and  are  derived  from  the  arcuate  fibres  and  the  fibrse  rectae  which 
have  altered  their  direction.  The  oblique  fibres  consist  of  the  deep 
arcuate  fibres  which  enter,  or  come  out  of  the  septum,  and  then 
pass  to  the  outer  part  of  the  medulla.  Some  fibres,  again,  are 
transverse  commissural  fibres,  and  pass  into  the  opposite  anterior 
pyramid  or  the  formatio  reticularis,1  and  eventually  assume  a 
longitudinal  direction. 

GREY  MATTER  Although  in  the  lower  part  of  the  medulla  the 

OF  THE  MEDULLA,  grey  matter  in  its  interior  is  arranged  in  the  same 
way  as  it  is  in  the  spinal  cord,  yet  owing  to  the  course  of  the  de- 
cussating fibres  of  the  lateral  tracts  which  break  up  the  anterior 
grey  cornua  in  front,  and  to  the  diverging  restiform  bodies  and 
posterior  pyramids  behind,  the  grey  matter  in  the  upper  two-thirds 

1  The  formatio  reticularis  comprises  the  anterior  and  lateral  parts  of  the 
medulla,  and  consists  of  intersecting  fibres  which  cross  each  other  at  right  angles, 
some  being  longitudinal  and  some  transverse  in  their  direction. 


730  .GREY   MATTER   OF   THE   MEDULLA. 

of  the  medulla,  becomes  altered  both  in  appearance  and  in  arrange- 
ment. 

The  grey  matter  of  the  anterior  cornua  soon  loses  its  charac- 
teristic arrangement,  as  it  becomes  detached  from  the  main  part  of 
the  grey  matter  by  the  passage  through  it  of  bundles  of  the  white 
fibres  of  the  medulla.  At  the  lower  part  of  the  olivary  body,  it 
is  pushed  backwards  and  outwards  in  consequence  of  the  increase 
of  the  anterior  pyramids  and  the  olivary  bodies,  so  as  to  lie  in  the 
lateral  part  of  the  medulla,  just  in  front  of  the  posterior  horn,  and 
constitutes  a  grey  nucleus  called  the  nucleus  lateralis.  The 
larger  portion  of  the  grey  matter  of  the  anterior  cornu  is  inter- 
sected by  white  fibres  and  becomes  broken  up  into  an  interlacement 
of  fibres  and  nerve-cells,  forming  the  formatio  reticularis. 

The  grey  matter  of  the  posterior  cornua  becomes  largely  in- 
creased in  the  upper  part  of  the  medulla.  At  first  the  posterior 
cornua  are  pushed  outwards  by  the  restiform  bodies,  and  subse- 
quently by  the  posterior  pyramids,  so  that  they  lie  at  right  angles 
to  the  posterior  median  fissure.  At  the  same  time  the  caput  cornu 
posterioris  enlarges,  and  later  on  forms  a  prominent  grey  mass,  the 
tubercle  of  Rolando,  which  becomes  separated  from  the  chief  part  of 
the  grey  matter  by  being  intersected  by  transverse  and  longitudinal 
white  fibres.  Internal  to  the  tubercle  of  Rolando,  there  are 
situated  masses  of  grey  matter  in  the  restiform  bodies  and  the 
posterior  pyramids,  constituting  their  nuclei.  Higher  up  on  a 
level  with  the  middle  of  the  olivary  body,  we  find  internal  to  the 
grey  matter  of  the  posterior  pyramid  (nucleus  gracilis)  the  nuclei 
of  origin  of  the  two  portions  of  the  pneumogastric  nerve,  and  of  the 
hypoglossal  nerve,  the  latter  being  nearest  the  middle  line. 

The  central  canal  gradually  approaches  the  posterior  surface 
of  the  medulla,  and  above  the  middle  of  it  opens  out  to  form  the 
median  groove  in  the  floor  of  the  fourth  ventricle.  On  each  side 
of  the  groove  we  find  a  collection  of  grey  matter  which  enlarges 
in  the  upper  part  and  constitutes  the  nucleus  teres. 

The  nuclei  of  the  origins  of  the  spinal  accessory,  the  pneumo- 
gastric, and  the  glosso-pharyngeal  nerves  will  be  described  subse- 
quently. 


.PONS   VAEOLII.  731 


PONS   VAEOLII. 

The  pons  Varolii,  or  tuber  annulare,  is  the  convex  eminence  of 
transverse  white  fibres  (fig.  171),  which  is  situated  at  the  base  of 
the  brain  immediately  above  the  medulla  oblongata.  It  rests  upon 
the  basilar  groove  of  the  occipital  and  the  sphenoid  bones,  and  in 
its  antero-posterior  diameter  measures  rather  more  than  an  inch. 
Its  upper  margin  is  convex  and  well  defined,  and  arches  over  the 
crura  cerebri ;  the  lower,  also  well  defined,  is  nearly  straight,  being 
separated  from  the  medulla  by  a  transverse  groove.  Laterally,  the 
pons  becomes  narrower,  in  consequence  of  its  transverse  fibres 
being  more  closely  aggregated ;  these  enter  the'  anterior  and  under 
part  of  the  cerebellum,  constituting  its  middle  peduncle.  Along  the 
middle  runs  a  shallow  groove,  broader  in  front  than  behind,  which 
lodges  the  basilar  artery.  If  the  pia  mater  be  removed,  we  observe 
how  the  superficial  fibres  pass  transversely,  to  connect  the  two 
hemispheres  of  the  cerebellum.  Throughout  the  mammalia  the 
size  of  the  pons  bears  a  direct  ratio  to  the  degree  of  development 
of  the  lateral  lobes  of  the  cerebellum ;  therefore  it  is  larger  in  man 
than  in  any  other  animal.1 

The  pons  consists  of  four  layers  of  alternating  transverse 
and  longitudinal  white  fibres,  intermingled  with  more  or  less  grey 
matter,  which  is  chiefly  found  on  its  upper  surface,  where  it  forms 
part  of  the  floor  of  the  fourth  ventricle. 

The  superficial  layer  of  white  fibres  is  transverse,  connecting 
the  cerebellar  hemispheres ;  the  middle  fibres  pass  transversely 
across,  the  inferior  ascend  slightly,  while  the  superior  pass  back- 
wards and  outwards  to  enter  the  cerebellum. 

The  second  layer  consists  of  longitudinal  fibres  which  are  the 
continuation  of  the  fibres  of  the  medulla  oblongata  in  their  passage 
to  the  cerebrum.  It  is  mainly  composed  of  fibres  derived  from  the 
anterior  pyramids  which  pass  up  to  form  the  superficial  fibres,  crusta, 
of  the  crura  cerebri. 

1  Birds,  reptiles,  and  fishes  have  no  pons,  as  there  are  no  lateral  lobes  to  the 
cerebellum. 


732  THE   CEREBRUM. 

The  third  layer  is  formed  of  transverse  fibres,  which  from 
their  peculiar  arrangement  take  the  name  of  trapezium ;  the  fibres 
in  their  course  outwards  pass  round  in  front  of  the  superior  olivary 
nuclei,  then  across  the  fasciculi  of  the  facial  nerves,  and  lastly  in 
front  of  the  ascending  roots  of  the  fifth  nerves  to  enter  the  middle 
peduncle  of  the  cerebellum. 

The  deepest  and  uppermost  layer  is  composed  of  longitudinal 
nerve-fibres  :  those  derived  from  the  olivary  fasciculi  divide  into 
two  bundles,  one  ascending  to  the  corpora  quadrigemina,  the  other 
passing  to  the  cerebrum ;  and  those  derived  from  the  lateral  and 
posterior  columns  of  the  cord,  which,  with  a  fasciculus  from  the 
fillet,  form  the  fasciculi  teretes  in  the  floor  of  the  fourth  ventricle, 
and  pass  upwards  to  form  the  tecjmenta,  or  deeper  portions  of  the 
crura  cerebri. 

The  grey  matter  is  chiefly  aggregated  at  the  posterior  part  of 
the  pons,  and  varies  in  thickness  in  different  sections.  Thus  a 
section  through  the  middle  of  the  pons  will  show  the  following 
nuclei  of  grey  matter,  beginning  from  the  central  groove  and  passing 
outwards ;  a  small  intermediate  portion  of  the  facial  nerve,  the 
large  nucleus  of  the  sixth,  the  facial  nerve,  the  large  superior 
nucleus  of  the  auditory  nerve  ;  while  below  we  notice  the  superior 
olivary  nucleus,  the  nucleus  of  the  facial  nerve,  and  externally  the 
grey  substance  of  Rolando,  enclosing  the  ascending  root  of  the 
fifth  nerve. 

The  pons,  like  the  medulla  oblongata,  has  an  imperfect  median 
septum,  composed  of  horizontal  fibres,  some  of  which  at  the  anterior 
border  surround  the  crura  cerebri. 


THE    CEKEBEUM. 

The  cerebrum  in  man  is  so  much  more  developed  than  the  other 
parts  of  the  encephalon  that  it  completely  overlies  them,  and 
forms  by  far  the  largest  portion.  It  is  oval  in  form,  and  convex 
on  its  external  aspect.  It  is  divided  in  the  middle  line  into  two 
symmetrical  parts,  termed  the  right  and  left  hemispheres,  by  the 
deep  longitudinal  fissure,  which  is  occupied  by  the  falx  cerebri 


THE   CEREBRUM. 


733 


FIG.  174. 


(p.  9).1  The  cerebrum  is  composed  of  numerous  parts 
certain  internal  ganglionic  masses,  the 
corpora  striata,  optic  thalami,  and  corpora 
quadrigemina ;  of  commissural  white 
fibres,  the  fornix,  corpus  callosum,  and 
the  commissures  of  the  third  ventricle ; 
of  the  pineal  and  pituitary  bodies  ;  and, 
lastly,  of  the  two  lateral  hemispheres, 
which  overlie  and  conceal  the  parts  pre- 
viously mentioned. 

The  cerebrum  rests  upon  the  anterior 
and  middle  fossas  of  the  base  of  the  skull, 
and  the  tentorium  cerebelli.  There  are 
three  surfaces  to  each  hemisphere :  an 
external  or  convex ;  an  inner  or  median  ; 


-viz.,  of 


DIAGRAM   OF   THE    GENERAL 
DIVISIONS   OF    THE    BRAIN. 


1,  2,  3.  Anterior,  middle,  and  poste- 
rior lobes  of  the  cerebrum. 
4.  Cerebellum. 
-,  .,,...  ,     T   -i       .-.       ,.  5.  Pons  Varolii. 

and  an  inferior,  interrupted  by  the  nssure    6.  Medulla  obiongata. 
of  Sylvius. 

By  widely  separating  the  two  hemispheres  at  the  longitudinal 
fissure  (the  brain  being  in  its  natural  position),  we  discover  that 
they  are  connected  in  the  middle  by  the  transverse  white  com- 
missure, called  the  corpus  callosum.  In  front  of,  and  behind  this 
mass,  the  longitudinal  fissure  extends  to  the  base  of  the  brain. 

The  cerebral  hemispheres,  viewed  from  above,  form  an  ovoid 
mass,  broader  in  front  than  behind,  and  convex  to  correspond  with 
the  vault  of  the  calvarium.  Their  surface  is  mapped  out  by  tor- 
tuous eminences  termed  convolutions  (gyri),  separated  from  each 
other  by  deep  furrows  (sulci),  which  extend  to  a  variable  depth. 
Many  of  the  sulci  are  occupied  by  large  veins  in  their  course  to  the 
sinuses ;  others  are  filled  with  subarachnoid  fluid.  The  convolu- 
tions are  folds  of  the  brain,  and  their  outer  surface  consists  of  grey 
matter,  so  that  the  extent  of  the  grey  substance  is  thus  very  largely 

1  Examples  are  occasionally  met  with,  where  the  longitudinal  fissure  is  not 
exactly  in  the  middle  line,  the  consequence  of  which  want  of  symmetry  is,  that 
one  hemisphere  is  larger  than  the  other.  Bichat  (Recherches  physiologiques  sur 
la  Vie  ki  la  Mort,  Paris,  1829)  was  of  opinion  that  this  anomaly  exercised  a 
deleterious  influence  on  the  intellect.  It  is  remarkable  that  the  examination  of 
his  own  brain  after  death  went  to  prove  the  error  of  his  theory. 


734  THE   CEKEBRUM. 

increased ;  the  grey  matter  here  is  called  the  cortical  substance. 
The  interior  of  the  convolutions  consists  of  white  nerve  substance. 
The  convolutions  are  not  symmetrical  on  both  sides,  although  they 
follow  a  somewhat  similar  arrangement.  The  number,  arrange- 
ment, and  depth  of  the  convolutions  vary  somewhat  in  different 
individuals,  and,  to  a  certain  extent,  may  be  considered  an  index 
of  the  degree  of  intelligence.1 

The  depth  of  the  sulci  between  the  convolutions  varies  in 
different  brains,  from  an  inch  to  half  an  inch  ;  hence  it  follows  that 
two  brains  of  equal  size  may  be  very  unequal  in  point  of  extent  of 
surface  for  the  grey  matter,  and  therefore  in  amount  of  intellectual 
capacity.  Under  the  microscope  the  cortical  layer  is  seen  to  con- 
sist of  four  layers — two  of  grey  alternating  with  two  of  white — the 
external  layer  being  always  white.  These  layers  are  not  equally 
thick  in  all  situations,  and  in  some  parts  six  layers  may  be  demon- 
strated, owing  to  the  interpolation  of  a  layer  of  white  substance  in 
the  outer  stratum  :  these  are  chiefly  seen  near  the  corpus  callosum 
and  in  the  occipital  lobe.2 

Some  of  the  sulci,  from  their  depth,  regularity,  and  early  period 
of  development,  are  termed  the  primary  or  interlobar  fissures,  and 
map  out  the  surface  of  the  cerebrum  into  five  lobes.  Of  these  sulci 
there  are  three :  the  fissure  of  Sylvius,  the  fissure  of  Rolando  or 
central  fissure,  and  the  parieto-occipital  fissure  (fig.  175). 

The  fissure  of  Sylvius  is  seen  on  the  base  of  the  cerebrum,  where 
it  receives  the  lesser  wing  of  the  sphenoid  bone.  It  begins,  outside 
the  locus  perforatus  anticus,  as  a  deep  triangular  depression — valle- 
cula  Sylvii — and  then  curves  outwards  as  a  deep  cleft  to  the  external 
surface  of  the  cerebrum ;  it  divides  into  two  rami — an  ascending  or 

1  Those  who  wish  to  investigate  the  cerebral  convolutions  in  their  simplest  form 
in  the  lower  classes  of  mammalia,  and  to  trace  them  through  their  successive 
development  and  arrangement  into  groups  as  we  ascend  to  the  higher  classes, 
should  consult  Leuret,  Anatomic  compares  du  Systeme  Nerveux  consideree  dans 
ses  Rapports  avec  V Intelligence,  Paris,  1839 ;  also  Foville,  Traite  de  I'Anat.  du 
Systeme  Nerveux,  &c.,  Paris,  1844.     The  convolutions  of  the  human  brain  have 
been  described  by  Ecker,  On  the  Convolutions  of  the  Human  Brain,  1873 ;  and 
by  Turner,  The  Convolutions  of  the  Human  Brain  topographically  considered, 
Edin.  1866. 

2  For  an  account  of  these  laminae,  see  Lock'hart  Clarke,  Proceedings  of  the  Royal 
Society,  1863. 


FISSURES    OF  THE   CEREBRUM. 


735 


vertical,  about  an  inch  in  length,  and  a  posterior  or  horizontal 
ramus,  which  passes  backwards  and  slightly  upwards,  and  ends  at 
the  posterior  third  of  the  cerebrum  by  a  bifid  extremity.  Within 
the  fissure,  near  its  commencement,  a  series  of  convolutions  may  be 


VIEW  OF  THE  CONVOLUTIONS  AND  FISSUBES  OF  THE  EXTERNAL  SURFACE  OF  THE 
BRAIN  (LEFT  SIDE). 


A.  Fissure  of  Rolando. 

B.  Fissure  of  Sylvius. 

c.  Inter-parietal  fissure. 

P.O.  Parieto-occipital  fissure. 

e.m.  Calloso-marginal  fissure. 

p.  Frontal  lobe. 

p.  Parietal  lobe. 

o.  Occipital  lobe. 

T.S.  Temporo-sphenoidal  lobe. 

A.F.  Ascending  frontal  convolution. 

A. p.  Ascending  parietal  convolution. 


/ii/M/a-  Superior,  middle,  and  inferior  frontal 
convolutions,  separated  by  the  superior  and 
inferior  frontal  sulci. 

plt  py  Superior  and  inferior  parietal  convolu- 
tions, separated  by  the  inter-parietal  fissure. 

°it  Ox  °3-  Superior,  middle,  and  inferior  occi- 
pital convolutions,  separated  by  the  occipital 
fissures. 

f,,  tx  t3.  Superior,  middle,  and  inferior  temporo- 
sphenoidal  convolutions,  separated  by  the  supe- 
rior and  inferior  temporo-sphenoidal  fissures. 


seen  deeply  placed ;  these  are  called  the  gyri  operti,  or  the  island  of 
Reil.  In  the  fork  between  the  two  rami  of  the  Sylvian  fissure  are 
several  convolutions,  which  have  been  termed  by  Broca  the  oper- 
eulum  of  the  insula. 

The  fissure   of  Rolando  or  central  fissure   (fig.  175,  A)   runs 


736 


FISSURES    OF   THE    CEREBRUM. 


obliquely  over  the  outer  convex  surface  of  the  hemisphere.  It 
commences  close  to  the  longitudinal  fissure  about  its  middle,  from 
which  it  is  separated  by  the  marginal  convolution.  It  then  runs 
obliquely  downwards  and  forwards,  and  terminates  a  little  above 


FIG.  176. 


CONVOLUTIONS  OF  THE  UPPEK  SURFACE  OF  THE  BRAIN. 


A.  Fissure  of  Rolando. 

A.F.  Ascending  frontal  convolution. 

A.P.  Ascending  parietal  convolution. 

S.M.  Supra-marginal  convolution,  below  which 

is  the  angular  gyrus. 
P.o/.  Parieto-occipital  fissure. 
F.  Frontal  lobe, 
p.  Parietal  lobe. 


o.  Occipital  lobe. 

f \ifafv  Superior,  middle  and  inferior  frontal 
convolutions. 

PD  Pa.  Superior  and  inferior  parietal  convolu- 
tions. 

O,,  O2)  O3.  Superior,  middle  and  inferior  occipital 
convolutions. 

C.mJ.  Calloso-marginal  fissure. 


the  fork  of  the  Sylvian  fissure.  As  seen  in  fig.  176,  the  two 
fissures  form  a  V-shape,  failing  to  be  joined  at  the  angle.  The 
fissure  is  formed,  in  early  foetal  life,  by  a  large  vein,  which  subse- 
quently atrophies,  and  is  rarely  bridged  over. 

The  pariet o-occipital  fissure  (fig.  178,  P.O.)  is  seen  on  the  median 


CONVOLUTIONS  OF  THE  CEREBRUM.  737 

surface  of  the  hemisphere,  towards  its  posterior  part.  It  begins 
as  a  deep  cleft  on  the  median  surface,  about  half  an  inch  behind 
the  corpus  callosum,  then  ascends  nearly  vertically,  and  ends  on 
the  external  aspect  of  the  cerebrum,  about  an  inch  beyond  the 
longitudinal  fissure ;  this  latter  portion  taking  the  name  of  the 
external  parieto-occipital  fissure. 

The  fissure  of  Sylvius  is  first  seen  about  the  middle  of  the 
third  month  of  fcetal  life,  and  is  caused  by  the  extension  back- 
wards, and  folding  upon  itself,  of  the  mantle  •  the  fissure  of 
Rolando  begins  to  be  developed  about  the  fifth  month ;  and  the 
parieto-occipital  fissure  between  the  third  and  fourth  month  of 
uterine  life. 

The  primary  fissures  form  the  boundaries  of  the  various  lobes 
of  which  each  hemisphere  is  composed. 

The  frontal  lobe  is  that  part  of  the  front  portion  of  the  cere- 
brum, bounded  behind  by  the  fissure  of  Rolando,  below  by  the 
anterior  part  of  the  fissure  of  Sylvius,  and  on  the  median  plane  by 
the  calloso-marginal  fissure.  Its  inferior  part  rests  on  the  anterior 
fossa,  and  is  called  the  orMtal  surface,  while  its  convex  external 
surface  is  called  the  frontal  surface. 

The  convolutions  on  its  frontal  surface  are  four  in  number  : — The 
ascending  frontal  convolution  (fig.  175,  A.F.)  which  bounds,  in  front, 
the  fissure  of  Rolando,  and  is  usually  connected  above  and  below 
the  fissure  with  the  ascending  parietal  convolution ;  the  union 
below  forming  the  opercidum,  the  union  above  part  of  the  para- 
central  lobule ;  the  upper  and  the  lower  union  of  these  two  convo- 
lutions thus  shut  off  the  fissure  of  Rolando  from  joining  the  fissure 
of  Sylvius  below,  and  the  longitudinal  fissure  above. 

The  superior,  middle,  and  inferior  frontal  convolutions  (fig.  1 75, 
jfj,  /2, /3)  course  nearly  horizontally ;  the  superior  runs  along  the 
margin  of  the  longitudinal  fissure,  the  inferior  along  the  lower  border 
of  the  lobe,  arching  over  the  ascending  ramus  of  the  Sylvian 
fissure  ;  the  middle  is  placed  between  these.  In  front  of  the  ascend- 
ing frontal  convolution  is  a  vertical  fissure,  prcecentral  sulcus,  which 
prevents  the  frontal  convolutions  joining  the  former  convolution. 

The  sulci  which  map  out  the  frontal  convolutions  are  two,  the 
superior  and  inferior  frontal  sulci. 

3B 


738  CONVOLUTIONS  OF  THE  CEREBRUM. 

On  the  orbital  surface  there  is  a  deep  sulcus,  the  trwadiate  sulcus, 
whose  rami  pass  forwards,  outwards,  and  backwards,  mapping  this 
surface  out  into  internal,  anterior,  and  posterior  orbital  convolu- 
tions (fig.  177,  2V.  8.)- 

On  this  surface  also  we  find  the  olfactory  lobe,  lodged  in  a  deep 
cleft,  the  olfactory  sulcus  (fig.  177,  Olf.  s.),  and  although  it  will  be 
described  under  the  cranial  nerves,  it  is  strictly  a  cerebral  lobe, 
for  it  is  developed  as  a  distinct  outgrowth  from  the  anterior 
cerebral  vesicle  ;  moreover,  in  early  foetal  life  it  possesses  a  cavity 
continuous  with  the  general  ventricular  cavity  of  the  brain. 

The  parietal  lobe  (fig.  175,  P)  is  placed  between  the  fissure  of 
Rolando  and  the  external  parieto-occipital  fissure,  and  is  bounded 
below  by  the  horizontal  limb  of  the  fissure  of  Sylvius,  and  by  a 
line  continued  from  it  to  meet  one  passing  down  from  the  parieto- 
occipital  fissure. 

The  convolutions  of  the  parietal  lobe  are  three  : — The  ascend- 
ing parietal  convolution  is  bounded  in  front  by  the  fissure  of 
Rolando,  and  runs  parallel  with  the  ascending  frontal  convolution 
in  front,  which  it  joins  above  and  below  the  fissure. 

The  superior  parietal  convolution  (fig.  175,  p)  is  placed  above 
the  interparietal  fissure,  and  courses  horizontally  backwards ; 
posteriorly  it  runs  beneath  the  parieto-occipital  fissure,  and  is  con- 
nected with  the  superior  occipital  convolution ;  this  is  known  as 
the  first  annectent  convolution ;  this  convolution  is  also  seen  on  the 
median  surface  of  the  cerebrum.  The  inferior  parietal  convolution 
lies  below  the  interparietal  fissure,  and  consists  of  two  portions : 
one,  the  supra-marginal,  lies  in  front  of  the  posterior  ramus  of  the 
Sylvian  fissure  ;  the  other,  the  angular  gyrus,  lies  behind  the  fissure 
of  Sylvius,  and  bends  over  the  termination  of  the  parallel  sulcus ; 
the  angular  convolution  is  connected  behind  with  the  occipital  con- 
volutions by  the  second  and  third  annectent  convolutions. 

The  interparietal  fissure  ascends  at  first  nearly  vertically,  and 
then  runs  horizontally  backwards  from  the  ascending  parietal  con- 
volution. 

The  occipital  lobe  (fig.  175,  o)  consists  of  the  posterior  part  of 
the  hemisphere  behind,  bounded  in  front  by  the  external  parieto- 
occipital  fissure,  and  by  a  line  continued  from  it. 


CONVOLUTIONS  OF  THE  CEREBRUM. 


739 


The  convolutions  on  the  external  surface  are  three : — 
The  superior,  middle,  and  inferior  occipital  convolutions  (fig.  175, 
°i>  °25  Oa)  run  nearty  horizontally  backwards,  and  are  separated  by 
the  superior  and  inferior  occipital  fissures  ;  anteriorly  these  convo  - 
lutions  are  continuous  with  the  parietal  and  temporo-sphenoidal 
convolutions,  through  the  four  annectent  yyri.  The  first  three 
have  been  previously  described  ;  the  lowest  or  fourth  connects  the 
inferior  occipital  with  the  inferior  temporo-sphenoidal  convolution. 

FIG.  177. 


CONVOLUTIONS    OF    THE    BASE    OF    THE    CEREBKTTM. 


0/r'.s.  Olfactory  sulcus. 
Tr.s.  Tri-radiate  sulcus. 
U.  TJncinate  convolution. 


Cal.f.  Calcarine  fissure. 
T,,  TO,  TV  Superior,  middle,  and  inferior 
temporo-spheuoidal  convolutions. 


There  is  usually  a  small,  shallow,  vertical  fissure,  the  transverse 
occipital,  which  passes  down  behind  the  external  parieto-occipital 
fissure. 

On  the  median  plane  is  the  cuneate  lobule,  which  forms  part  of 
the  occipital  lobe,  and  will  be  described  further  on. 

The  temporo-sphenoidal  lobe  is  bounded  in  front  and  above  by 

3  B  2 


740  CONVOLUTIONS  OF  THE  CEREBRUM. 

the  fissure  of  Sylvius  and  its  horizontal  ramus,  and  forms  that  part 
of  the  hemisphere  which  occupies  the  middle  cerebral  fossa. 

The  convolutions  of  this  lobe  are  three  : — 

The  superior  temporo-splienoidal  (fig.  178,  £,)  is  bounded  above 
by  the  horizontal  ramus  of  the  Sylvian  fissure,  and  below  by  the 
parallel  fissure ;  it  is  continuous  behind  with  supra-marginal  and 
angular  gyri.  The  middle  temporo-splienoidal  is  joined  behind  to 
the  angular  gyrus  and  to  the  middle  occipital  convolution  through 
the  third  annectent  gyrus ;  the  inferior  is  connected  with  the 
inferior  occipital  convolution  through  the  fourth  annectent  gyrus. 

There  are  three  fissures  running  from  before  backwards,  the 
superior  temporo-splienoidal  or  parallel,  the  middle,  and  the  inferior. 

The  convolutions  and  fissures  of  the  median  and  tentorial 
surfaces  can  only  be  properly  examined  by  making  an  antero- 
posterior  vertical  section  of  the  brain  through  the  longitudinal 
fissure.  As  this  would  spoil  the  brain  for  future  demonstration, 
the  student  is  recommended  to  examine  one  in  which  this  section 
has  been  already  done. 

The  fissures  to  be  examined  on  this  surface  are  the  calloso- 
marginal,  the  internal  parieto-occipital,  the  calcarine,  the  collateral, 
and  the  hippocampal  or  dentate. 

The  convolutions  are  the  prsecuneus,  the  cuneate,  the  uncinate, 
the  marginal,  the  gyrus  fornicatus,  and  the  dentate. 

The  calloso-marginal  fissure  commences  beneath  the  rostrum  of 
the  corpus  callosum,  curves  in  front  and  round  the  genu,  and  then 
runs  nearly  parallel  with  the  anterior  two-thirds  of  the  corpus 
callosum ;  then,  changing  its  direction,  it  ascends  obliquely  and 
terminates  on  the  external  aspect  of  the  hemisphere,  where  it 
forms  a  deep  notch  immediately  behind  the  fissure  of  Rolando. 

The  internal  parieto-occipital  fissure  passes  nearly  vertically 
downwards,  and  joins  the  calcarine  fissure  at  an  acute  angle. 

The  calcarine  fissure  begins  close  to  the  posterior  border  of  the 
cerebrum,  and  then,  running  nearly  horizontally  forwards,  is  joined 
by  the  preceding  fissure ;  it  terminates  a  little  below  the  posterior 
border  of  the  corpus  callosum.  It  corresponds  with  the  hippo- 
campus minor  in  the  -posterior  horn  of  the  lateral  ventricle. 

The  collateral  fissure  (fig.  178,  Gl.f.)  is    situated   below    the 


CONVOLUTIONS  OF  THE  CEREBRUM. 


741 


calcarine  fissure,  and  runs  parallel  with  it.  It  separates  the 
superior  and  inferior  occipito-temporal  convolutions,  and  causes 
the  eminentia  collaterals  in  the  descending  horn  of  the  lateral 
ventricle. 

The  liippocampal  fissure  takes  its  origin  in  the  posterior  part  of 
the  gyrus  fornicatus,  and,  passing  downwards  and  forwards,  it  ends 
by  forming  the  notch  in  the  uncinate  gyrus.  It  corresponds  to 
the  hippocampus  major. 

FIG.  178. 


CONVOLLTIONS   AND    FISSURES    OF    THE    MEDIAN    AND    TENTOBIAL    SUBFACES    OF 
RIGHT    HEMISPHERE. 


f.c.  Corpus  callosum. 

A.F.  Ascending  frontal  convolution. 

A.i1.  Ascending  parietal  convolution. 

P.O.  Parieto-occipital  fissure. 

p.c.  Prsecuneus  or  quadrate  lobe. 

c.  Cuueus. 

c.  Calcarine  fissure. 

C7,/.  Collateral  fissure. 


G.F.  Gyrus  fornicatus. 
cm.  Calloso-marginal  fissure. 
fi.  Superior  frontal  or  marginal  convolution. 
o.T.  Optic  thalamus. 
P.  Pituitary  body. 
tic.  Dentate  convolution. 
tot.  Gyrus  occipito-temporalis  lateralis. 
to-,  Gyrus  occipito-temporalis  medialis. 


The  prcecuneus,  or  quadrate  lobule  (fig.  178,  P.C.),  is  bounded 
in  front  by  the  calloso-marginal  fissure,  behind  by  the  internal 
parieto-occipital  fissure.  It  consists  of  numerous  convolutions, 
and  belongs  to  the  parietal  lobe. 

The  cuneate  lobule  (fig.  178,  c)  is  triangular  in  shape,  and  is 
situated  between  the  converging  internal  parieto-occipital  and 
calcarine  fissures.  It  is  part  of  the  superior  occipital  convolution. 

The  f/yr  us  fornicatus  (fig.  178,  G.F.)  begins  in  front  of  the  locus 


742  BASE    OF   THE    BRAIN. 

perforatus  anticus,  and  winds  round  the  corpus  callosum,  keeping 
close  to  its  upper  surface.  It  curves  round  its  posterior  free  border, 
and  is  continuous  below  with  the  uncinate  gyrus.  Between  this 
convolution  and  the  corpus  callosum  is  a  well-marked  furrow, 
which  sometimes  takes  the  name  of  the  ventricle  of  the  corpus 
callosum.  The  part  of  the  convolution  that  forms  the  boundary 
of  this  ventricle  is  termed  the  lalnum  cerelri. 

The  dentate  convolution  (fascia  dentata,  fig.  1  78,  dc)  is  the  grey 
convolution  lying  in  the  dentate  fissure,  and  takes  its  name  from 
the  notched  appearance  it  presents,  owing  to  the  arrangement  of 
the  choroid  arteries  as  they  pass  in  through  the  fissure  into  the 
descending  horn  of  the  lateral  ventricle. 

The  uncinate  gyrus  (fig.  177,  u)  is  the  anterior  part  of  the 
superior  occipito-temporal  convolution,  which  ends  in  a  peculiar 
hook-like  process  at  the  front  of  the  temporo-sphenoidal  lobe. 

The  inferior  occipito-temporal  convolution  (fig.  178,  /o4)  is 
situated  between  the  collateral  and  the  inferior  temporo-sphenoidal 
fissures,  and  runs  backwards  to  the  posterior  border  of  the  cerebrum. 

The  marginal  convolution  skirts  the  longitudinal  fissure  from 
the  locus  perforatus  anticus  as  far  as  the  termination  of  the  calloso- 
marginal  fissure.  It  is  frequently  indented  by  secondary  furrows, 
and  usually  is  joined  to  the  gyrus  fornicatus. 

The  island  of  Reil,  or  the  central  lolte,  lies  deeply  in  the  fissure 
of  Sylvius,  not  far  from  its  commencement.  It  is  triangular  in 
shape,  the  apex  being  close  to  the  anterior  perforated  spot,  and 
from  it  radiate  outwards  five  or  six  short  convolutions  (gyri  operti), 
which  are  separated  from  the  operculum  by  a  deep  fissure.  In  the 
normal  position  of  the  brain,  it  forms  the  floor  of  the  lenticular 
nucleus  of  the  corpus  striatum.  It  appears  very  early  in  foetal 
life,  and  is  at  first  very  prominent,  but  subsequently  becomes 
closed  in  by  the  increasing  development  of  the  temporo-sphenoidal 
lobe. 

NOMENCLATURE          ^e  several  objects  seen  at  the  base  of  the  brain 

OF  THE  PARTS  AT       should  now  be  examined,  proceeding  in  order  from 

THE  BASE  OF  the  front  (fig.  170,  p.  718).     In  this  description 

the  cerebral  nerves  are  omitted.     These  will  be 

examined  hereafter. 


BASE    OF   THE    BRAIN.  743 

In  front  we  notice  the  triangular  frontal  lobes,  separated  from 
each  other  by  the  longitudinal  fissure,  and  bounded  behind  by  the 
fissure  of  Sylvius. 

In  the  middle  line,  dividing  the  frontal  lobes,  is  the  longi- 
tudinal fissure.  By  gently  separating  these  lobes,  we  expose  the 
corpus  callosum,  or  the  great  transverse  commissure  which  con- 
nects the  two  hemispheres  of  the  cerebrum.  Continued  backwards 
and  outwards  on  each  side  from  the  corpus  callosum  to  the  fissure 
of  Sylvius  is  a  white  band,  the  peduncle  of  the  corpus  callosum. 
Extending  from  the  corpus  callosum  to  the  optic  commissure  is  a 
thin  grey  layer,  the  lamina  cinerea.  Between  the  frontal  and 
temporo-sphenoidal  lobes  is  the  fissure  of  Sylvius,  which  lodges 
the  middle  cerebral  artery.  The  optic  commissure,  formed  by  the 
union  of  the  two  optic  tracts,  is  seen  in  the  middle  line  behind  the 
lamina  cinerea.  At  the  root  of  the  fissure  of  Sylvius  is  the  locus 
perforatus  anticus.1  Immediately  behind  the  optic  commissure  is 
a  slight  prominence  of  grey  matter,  the  tuber  cinereum  ;  from  this 
descends  a  conical  tube  of  reddish  colour,  the  infundibulum,  to  the 
apex  of  which  is  attached  the  pituitary  body.  Behind  the  tuber 
cinereum  are  two  round  white  bodies,  the  corpora  albicantia. 
Posterior  to  these  is  the  locus  perforatus  posticus,  which  is  bounded 
behind  by  the  pons,  and  laterally  by  the  two  diverging  crura  cere- 
bri,  two  round  cords  of  white  substance,  which  emerge  from  the 
anterior  border  of  the  pons.  Winding  round  the  outer  side  of  each 
crus  is  a  soft  white  band,  the  optic  tract. 

Examine  now  in  detail  the  various  objects  above  enumerated, 
most' of  which  are  shown  in  fig.  ]  70. 

The  longitudinal  fissure  is  visible  in  front,  where  it  separates 
the  two  frontal  lobes,  and,  by  lifting  up  the  cerebellum,  it  can  be 
seen  behind  dividing  the  temporo-sphenoidal  lobes.  It  can  be 
more  satisfactorily  examined  later  on. 

The  lamina  cinerea  is  a  thin  layer  of  grey  substance,  which 
runs  backwards  from  the  termination  of  the  corpus  callosum, 
and  passes  above  the  optic  commissure  to  be  connected  with  the 
tuber  cinereum.  Laterally  it  is  continuous  with  the  grey  matter 

1  Called  2>erforatm  from  its  being  perforated  by  a  number  of  blood-vessels  for 
the  supply  of  the  corpus  striatum. 


744  BASE    OF   THE    BRAIN. 

of  the  two  anterior  perforated  spots.  If  the  lamina  be  torn,  which 
is  very  easily  done,  an  opening  is  made  into  the  anterior  part  of 
the  floor  of  the  third  ventricle. 

The  olfactory  lobe  lies  in  its  own  sulcus  on  the  orbital  surface, 
nearer  its  mesial  aspect. 

The  optic  commissure  is  placed  immediately  behind  the  lamina 
cinerea.  It  is  formed  by  the  junction  in  the  middle  line  of  the 
two  optic  tracts.  From  it  the  two  optic  nerves  can  be  traced, 
running  forwards  and  outwards. 

The  locus  perforatus  anticus  is  a  shallow  triangular  depression, 
placed  to  the  inner  side  of  the  commencement  of  the  fissure  of 
Sylvius.  It  is  bounded  in  front  by  the  two  diverging  white  roots 
of  the  olfactory  lobe,  and  behind  by  the  optic  tract.  It  is  com- 
posed partly  of  grey  substance,  and  is  continuous  with  the  lamina 
cinerea  on  the  inner  side.  Crossing  it  is  seen  a  broad  white  band, 
the  peduncle  of  the  corpus  callosum.  This  space  is  pierced  by  a 
number  of  small  apertures  for  the  transmission  of  small  vessels  to 
the  corpus  striatum ;  hence  its  name. 

The  tuber  cinereum  (fig.  170,  p.  718)  is  a  prominence  of  grey 
matter  immediately  behind  the  optic  commissure,  and  in  front  of 
the  corpora  albicantia.  It  forms  -part  of  the  floor  of  the  third 
ventricle,  and  from  it  a  conical  tube  of  reddish  colour,  the  infundi- 
bulum,  descends  to  the  posterior  lobe  of  the  pituitary  body.  There 
is  a  large  collection  of  grey  matter  on  the  outer  side  of  the  tuber 
cinereum,  and  internal  to  the  optic  tract,  called  the  basal  optic 
ganglion,  from  which  fibres  pass  to  the  corresponding  optic  tract. 

The  pituitary  body  occupies  the  sella  turcica,  is  of  a  reddish- 
brown  colour,  and  consists  of  two  lobes.  Of  its  two  lobes  the 
anterior,  and  larger,  is  concave  posteriorly  to  receive  the  pos- 
terior lobe,  and  weighs  from  five  to  ten  grains.  The  two  lobes 
consist  of  different  structure,  and  differ  in  their  development ;  the 
posterior  is  developed  downwards  from  the  third  ventricle,  and  is 
hollow  ;  subsequently  there  is  a  large  increase  of  connective-tissue 
structure  and  blood-vessels  in  it,  so  that  the  cavity  is  usually 
obliterated.  The  anterior  is  darker,  and  is  surrounded  by  a  con- 
nective-tissue capsule ;  on  section  it  resembles  in  structure  the 
thyroid  gland,  being  composed  of  reticular  tissue,  with  numerous 


CRURA    CEREBRI.  745 

cavities  filled  with  nucleated  cells  and  granular  matter ;  it  is 
originally  developed  as  a  prolongation  from  the  ectoderm  of  the 
buccal  cavity,  from  which  it  soon  becomes  isolated. 

The  corpora  albicantia  (inammillaria)  are  two  round  white 
bodies,  situated  behind  the  tuber  cinereum.  Each  is  formed  by 
the  curl  upon  itself  of  the  anterior  crus  of  the  fornix,  called  the 
bulb  of  the  fornix,  which  then  turns  backwards  and  upwards  to 
end  in  the  optic  thalamus.  They  contain  within  them  some  grey 
matter,  and  up  to  the  seventh  month  of  fetal  life  they  form  one 
mass. 

The  locus  perforates  posticus  (^pons  Tarini)  is  a  depression  of  grey 
matter  placed  between  the  diverging  crura  cerebri  and  behind  the 
corpora  albicantia.  Its  surface  is  penetrated  by  small  vessels  which 
supply  the  optic  thalami.  From  its  grey  substance  some  white 
fibres  emerge  and  turn  round  over  the  crura  cerebri  to  enter  the 
white  medullary  portion  of  the  cerebellum. 

The  crura  cerebri  (fig.  170)  are  the  two  rounded  masses  of 
white  matter  which  emerge  from  the  anterior  border  of  the  pons 
Varolii,  and  then  pass  forwards  and  outwards  to  enter  the  anterior 
and  inner  aspect  of  the  temporo-sphenoidal  lobes.  Each  is  about 
three-quarters  of  an  inch  long,  and  is  rather  broader  in  front  than 
behind.  On  the  inner  side  the  third  nerve  is  seen  emerging  from 
a  groove  (oculo-motor)  in  the  crus,  which  marks  the  division  of  the 
crus  into  two  portions,  an  upper  (dorsal)  and  larger  called  the 
tegmentum,  and  a  lower  or  ventral,  called  the  crusta.  The  optic 
tract  curves  round  the  anterior  part  of  each  crus,  and  is  adherent 
to  it  by  its  anterior  border. 

STRUCTURE  OF  These  are  composed  of  longitudinal  fibres,  de- 

THE  CRUKA  rived  from  the  pyramids,  from  part  of  the  lateral 

CEREBRI.  an(j  restiform  columns  of  the  medulla,  and  from  the 

grey  matter  in  the  pons  Varolii.  If  one  of  the  crura  be  divided 
longitudinally,  there  is  found  in  the  middle  of  it  a  layer  of  dark- 
coloured  nerve-substance,  called  locus  niyer,  which  separates  the 
crus  into  an  upper  and  lower  stratum  of  fibres.  The  lower  stratum 
(crustci)  is  tough  and  coarse,  and  consists  of  the  continuation  of  the 
fibres  proceeding  from  the  pyramid  and  the  pons.  The  upper 
stratum  (teymentmn)  is  much  softer  and  finer  in  texture;  it  is 


746 


ORIGINS    OF    THE    CRANIAL   NERVES. 


composed  of  the  fibres  proceeding  from  the  lateral  and  restiform 
columns  ;  also  from  the  superior  crus  of  the  cerebellum.  Tracing 
the  fibres  of  the  crus  cerebri  into  the  cerebral  hemisphere,  we  find 
that  its  lower  fibres  ascend  chiefly  through  the  corpora  striata,  its 
upper  fibres  through  the  thalami  optici.  In  passing  through  these 
ganglia,  the  crus  receives  a  large  addition  to  its  fibres :  these 

FIG.  179. 


Corpus  striatnm. 

Thalamus  opticus. 

Crus  cerebri. 

Locus  niger. 

Pons  Varolii,  denoted  by 

transverse  lines. 
Pyramid. 
Olive. 

Anterior  columns. 
Lateral  columns. 
Posterior  columns. 
Corpora  quadrigemina. 
Fillet  of  Reil. 
Superior   crus  of    the 

cerebellum. 
Cerebellum. 


DIAGRAM    OF    THE    COURSE    OF    THE    FIBRES    THROUGH    THE    MEDULLA   AND    PONS. 


branch  out  widely  towards  all  parts  of  the  hemisphere,  in  order  to 
reach  the  cortical  substance  on  the  surface. 

ORIGIN  OF  THE  The  cerelral  nerves  are  given  off  in  pairs,  named 

CEREBRAL  the  first,  second,  third,  &c.,  according  to  the  order 

NERVES.  jn  which  they  appear,  beginning  from  the  front. 

There  are  twelve  pairs.     Some  are  nerves  of  special  sense  —  as  the 


ORIGINS    OF   THE    CRANIAL    NERVES. 


747 


olfactory,  the  optic,  the  auditory;  others  are  nerves  of  common 
sensation — as  the  larger  root  of  the  fifth,  the  glosso-pharyngeal, 
and  the  pneumogastric ;  others,  again,  are  nerves  of  motion — as 
the  third,  the  fourth,  the  smaller  root  of  the  fifth,  the  sixth,  the 
facial,  the  spinal-accessory,  and  the  hypoglossal. 

FIRST  PAIK  OB  These  (fig.  180,  i)  are  from  their  early  develop- 

OLFACTOBY  ment  outgrowths  from  the  cerebral  lobes,  and  not, 

strictly  speaking,  nerves.     The  nerve  is  triangular 


NERVES. 


FIG.  180. 


1.  Olfactory  lobe. 

2.  Optic  n. 

3.  Crus  cerebri. 

4.  Section  of   cms   to 

show  locus  niger. 

5.  Corpus  geniculatuin 

externum. 


G.  Corpus  geniculatnm 
internum. 

7.  Corpora        quadri- 
gemiiia. 

8.  Tlialamus  options. 

9.  Tractus  opticus. 
10.  Corpus  callosum. 


DIAGKAM   OFTHE     OKIGINS    OF     THE    OLFACTORY    AND    OPTIC    NERVES. 


on  section,  the  apex  of  the  triangle  being  lodged  in  a  straight  farrow 
(olfactory  sulcus)  in  the  orbital  surface  of  the  frontal  lobe.  It  pro- 
ceeds straight  forwards,  and  terminates  in  the  olfactory  bulb,  which 
lies  on  the  cribriform  plate  of  the  ethmoid  bone. 

The  olfactory  lobe  is  oval,  of  a  reddish-grey  colour,  and  very 
soft  consistence,  owing  to  the  large  amount  of  grey  matter  con- 
tained in  it.  It  gives  off  from  its  under  surface  about  twenty 


748  ORIGINS    OF   THE    CRANIAL    NERVES. 

branches,  which  pass  through  the  foramina  in  the  cribriform  plate.1 
For  description  of  these,  see  p.  277. 

The  nerve  arises  by  three  roots — an  outer  and  an  inner,  com- 
posed of  white  matter,  and  a  middle,  composed  of  grey  (fig.  180, 
p.  747). 

The  outer  root  passes  backwards  and  outwards  as  a  thin  white 
line,  along  the  outer  side  of  the  locus  perforatus  anticus,  to  the 
commencement  of  the  fissure  of  Sylvius.  Its  deeper  origin  has 
been  traced  to  a  nucleus  of  grey  matter  in  the  anterior  part  of  the 
temporo-sphenoidal  lobe. 

The  inner  root  passes  backwards  and  inwards  to  the  posterior 
extremity  of  the  internal  convolution  of  the  frontal  lobe,  and  thence 
may  be  traced  to  the  gyrus  fornicatus. 

The  middle  or  (jrey  root  arises  from  the  grey  matter  of  the 
sulcus  in  which  the  nerve  is  lodged,  and  from  the  grey  matter  of 
the  locus  perforatus  anticus  in  the  fork  between  the  two  white 
roots ;  this  is  called  the  tuber  olfactorium.  It  contains  white  fibres 
in  its  interior,  which  have  been  traced  to  the  corpus  striatum. 

SECOND  PAIR  The  optic  tracts  arise  from  the  anterior  lobes 

OK  OPTIC.  (iiates)  of  the  corpora  quadrigemina,  the  corpora 

geniculata,  and  the  posterior  part  of  the  optic  thalami  (p.  747, 
fig.  180).  They  wind  round  the  crura  cerebri,  with  which  they 
are  connected  by  their  anterior  borders,  and,  after  receiving  some 
fibres  from  the  basal  optic  nucleus  (p.  744),  join  in  the  middle  line 
to  form  the  optic  commissure.  This  commissure  rests  upon  the 
sphenoid  bone  in  front  of  the  sella  turcica ;  and  from  it  each  optic 
nerve,  invested  by  its  fibrous  sheath,  passes  through  the  optic 
foramen  into  the  orbit  and  terminates  in  the  retina. 


1  The  olfactory  nerve  and  its  ganglion,  as  stated  above,  are  integral  parts  (the 
prosencephalic  lobe)  of  the  brain.  What  in  human  anatomy  is  called  the  origin  of 
the  nerve  is,  in  point  of  fact,  the  crus  of  the  olfactory  lobe,  and  is  in  every  way 
homologous  to  the  crus  cerebri  or  cerebelli.  In  proof  of  this,  look  at  the  enormous 
size  and  connections  of  the  crus  in  animals  which  have  very  acute  sense  of 
smell.  Throughout  the  vertebrate  kingdom  there  is  a  strict  ratio  between  the 
sense  of  smell  and  the  development  of  the  olfactory  lobes.  Again,  in  many 
animals,  these  lobes  are  actually  larger  than  the  cerebral,  and  contain  in  their 
interior  a  cavity  which  communicates  with  the  lateral  ventricles.  According  to 
Tiedemann,  this  cavity  exists  even  in  the  human  totus  at  an  early  period. 


ORIGINS    OF   THE    CRANIAL   NERVES.  749 

At  the  commissure  some  of  the  nerve-fibres  cross  from  one  side 
to  the  other.  This  decussation  affects  only  the  middle  fibres  of  the 
nerve;  the  outer  fibres  pass  from  one  optic  tract  to  the  optic 
nerve  of  the  same  side ;  the  inner  fibres  pass  from  one  optic  tract 
round  to  the  optic  tract  of  the  opposite  side  ;  while  in  front  of  the 
commissure  are  fibres  which  pass  from  one  optic  nerve  to  its  fellow 
(p.  754). 

THIED  PAIR  The  apparent  origin  of  the  third  nerve  is  from 

OK  MOTOEES  the  inner  side  of  the  crus  cerebri,  immediately  in 

OCULOKUM.  front  of  the  pons.  Some  of  its  roots,  however, 

pass  through  the  locus  niger  and  the  tegmentum  of  the  crus,  to 
reach  a  nucleus  of  large  yellow  cells  beneath  the  iter  a  tertio  ad 
quartum  ventriculum,  extending  forwards  as  far  as  the  posterior 
commissure,  and  behind  as  far  as  the  nucleus  of  the  fourth  nerve 
(see  below).  It  runs  forwards  through  the  cavernous  sinus,  and, 
passing  through  the  sphenoidal  fissure  in  two  divisions,  supplies 
all  the  muscles  of  the  orbit  except  the  superior  oblique  and  the 
external  rectus. 

FOUETH  PAIE  The  fourth  nerve  has  its  deep  origin  from  a 

OB  TKOCHLEAR  nucleus  of  grey  matter  in  the  floor  of  the  aqueduct 
NEEVES.  of  Sylvius,  beneath  the  corpora  quadrigemina,  and 

almost  continuous  superiorly  with  the  yellow  nucleus  of  the  third 
nerve.  The  nerve  fibres  then  run  backwards,  upwards,  and  inwards 
in  the  lateral  wall  of  the  Sylvian  aqueduct,  and  reach  the  anterior 
part  of  the  valve  of  Vieussens,  where  they  cross  over  to  the  opposite 
side.  The  nerve  then  emerges  from  the  valve  of  Vieussens  close  to 
the  middle  line,  and,  winding  round  the  crus  cerebri,  enters  the 
orbit  through  the  sphenoidal  fissure  and  supplies  the  superior 
oblique. 

FIFTH  PAIK  OK  The  fifth  nerve  is  the  largest  of  all  the  cranial 

TRIGEMINAL  nerves,  and  consists  of  two  roots,  a  larger  or 

sensory,  and  a  smaller  or  motor.  It  has  its  appa- 
rent origin  from  the  outer  side  of  the  pons  Varolii,  and  a  few  of  the 
transverse  fibres  of  this  body  separate  the  two  roots  of  the  fifth. 
The  motor  or  smaller  root  consists  of  fibres  which  take  origin  from 
an  oval  grey  nucleus  (motor  nucleus)  situated  in  the  front  part  of 
the  floor  of  the  fourth  ventricle,  internal  to  its  lateral  boundary  ; 


750  ORIGINS   OF   THE   CRANIAL   NERVES. 

in  their  passage  forwards  the  fibres  are  joined  by  filaments  from 
the  descending1  root  of  the  fifth,  which  arise  from  the  grey  matter 
in  the  lateral  wall  of  the  aqueduct  of  Sylvius,  beneath  the  anterior 
lobes  of  the  corpora  quadrigemina.  It  also  receives  some  fibres 
from  the  raphe.  The  sensory  and  larger  root  arises  by  fibres  having 
their  origin  chiefly  in  the  superior  sensory  nucleus,  which  is  situated 
external  to  the  motor  nucleus,  and  partly  by  fibres  known  as  the 
ascending  fibres,  which  may  be  traced  far  down  in  the  medulla 
from  a  mass  of  nerve-cells  in  connection  with  the  grey  tubercle  of 
Rolando  and  its  upward  prolongation.  The  two  divisions  of  the 
nerve  proceed  forwards  over  the  apex  of  the  petrous  portion  of 
the  temporal  bone ;  here  is  developed,  upon  the  sensory  root,  the 
Gasserian  ganglion.  The  root  then  divides  into  three  branches — 
the  ophthalmic,  which  passes  through  the  sphenoidal  fissure ;  the 
superior  maxillary,  which  passes  through  the  foramen  rotundum ; 
the  inferior  maxillary,  which  passes  through  the-  foramen  ovale. 
They  all  confer  common  sensation  upon  the  parts  they  supply, 
which  comprise  the  entire  face  and  sides  of  the  head.  The  small 
motor  root  passes  beneath  the  ganglion,  with  which  it  has  no  con- 
nection, and  accompanies  the  inferior  maxillary  division,  to  be  dis- 
tributed to  the  muscles  of  mastication. 

SIXTH  PAIK  OB  The  sixth  nerve  emerges  from  the  transverse 

ABDUCENTES.  groove  between  the  pons  and  the  anterior  pyramid 

(p.  718),  with  both  of  which  it  is  connected.  Its  deep  origin  can 
be  traced  to  an  oval  grey  mass  of  nerve-cells  in  the  fasciculus  teres  in 
the  floor  of  the  fourth  ventricle,  close  to  the  median  groove  and  in 
front  of  the  transverse  striae.  The  nerve  fibres  pass  downwards 
from  their  origin  through  the  pons  parallel  with  the  septum,  and 
emerge  from  the  transverse  groove  as  before  stated.  It  leaves  the 
skull  through  the  sphenoidal  fissure,  and,  passing  between  the  two 
heads  of  the  external  rectus,  is  distributed  to  this  muscle. 

SEVENTH  PAIR  The  facial  nerve  or  portio  dura  (p.  718)  has  its 

OK  FACIAL  apparent  origin  from  the  groove  between  the  pons 

NEKVES.  an(j  ^jae  restiform  tract,  and  behind  the  olivary 

body.  Its  deep  origin  may  be  traced  to  an  elongated  mass  of 
grey  substance,  placed  deeply  in  the  floor  of  the  fourth  ventricle, 
between  the  motor  nucleus  of  the  fifth  and  the  transverse  strias. 


ORIGINS    OF   THE    CRANIAL    NERVES. 


751 


From  this  origin  its  fibres  run  upwards,  backwards,  and  inwards 
to  the  floor  of  the  fourth  ventricle,  and  wind  round  the  nucleus  of 
the  sixth,  so  as  to  course  superficial  to  it  in  the  fasciculus  teres. 
The  nerve  then  makes  a  sharp  bend  upon  itself,  and  passes 
downwards  and  outwards  through  the  pons  between  the  superior 
olivary  nucleus  and  the  ascending  root  of  the  fifth  nerve.  A  small 
separate  fasciculus  of  this  nerve — pars  intermedia — lies  between 
it  and  the  auditory  nerve,  and  forms  connections  with  both ;  it 
arises  from  the  lateral  column  of  the  cord.  The  nerve  enters  the 
meatus  auditorius  internus.  For  the  further  description  of  the 
portio  dura,  see  p.  44. 

FIG.  181. 


a.  Superior    peduncles 

of  the  cerebellum. 

b.  Eestiform  tracts. 

c.  Posterior  pyramids. 

d.  Fasciculus  teres  :  ex- 

ternal to  it  is  the 
superior  fovea. 


e.  Striie  acusticae. 
/.  Fasciculus  teres. 
y.  Tuberculum  acusti- 

cum. 

h.  Inferior  fovea. 
i.  Cerebellum. 


VIEW  OF  THE  FLOOE  OF  THE  FOURTH  VENTRICLE. 


EIGHTH  PAIR 
OK  AUDITORY 
NERVES. 


The  auditory  nerve  emerges  from  the  same 
groove  as  the  preceding  nerve,  and  is  situated 
immediately  beneath  it,  being  separated  from  it 
only  by  the  pars  intermedia.  Its  deep  origin  is  principally  from 
the  inner  auditory  nucleus,  situated  in  the  floor  of  the  fourth 
ventricle,  under  the  tuberculum  acusticum ;  this  nucleus  extends 
from  beneath  the  acoustic  tubercle  to  the  middle  of  the  anterior 
half  of  the  floor,  passing  beneath  the  transverse  striaa ;  on  its 
inner  side,  below,  is  the  vagal  nucleus,  on  its  outer  side  is  the 
restiform  body ;  from  this  nucleus  the  fibres  pass  outwards,  and, 
on  curving  round  the  restiform  body,  are  joined  by  some  filaments 


752  ORIGINS    OF    THE    CRANIAL    NERVES. 

from  the  transverse  striae.  A  few  of  the  filaments  of  the  auditory 
nerve  come  from  another  nucleus  situated  in  front  of  the  medullary 
striae  and  external  to  the  preceding  nucleus,  and  which  gets  larger 
as  it  passes  upwards.  These  two  bundles  unite,  and  the  nerve 
passes  outwards  and  enters  the  meatus  auditorius  internus  in  com- 
pany with  the  portio  dura.  It  divides  at  the  bottom  of  the  meatus 
into  cochlear  and  vestibular  branches,  which  are  distributed  to  the 
internal  ear. 

NINTH  PAIR  OB  ^he  fjlosso-plianjncjeal  nerve  arises  apparently 

GLOSSO-PHARYN-  by  several  filaments  from  the  restiform  body  below 
GEAL  NEKVES.  fa&  au(Jitory  nerve.  Its  deep  origin  is  from  a 

nucleus  in  the  inferior  fovea  of  the  fourth  ventricle,  continuous 
behind  with  the  vagal  nucleus,  and  covered  in  front  by  the  inner 
auditory  nucleus.  The  glosso-pharyngeal  nerve  passes  through 
the  middle  compartment  of  the  foramen  jugulare,  and  is  distri- 
buted to  the  mucous  membrane  of  the  pharynx  and  back  of  the 
tongue  (p.  265). 

TENTH  PAIR  OB  r^ne  pneumogastric  nerve  arises  from  a  grey 
PNETJMOGASTRIC  nucleus  (divided  into  two  by  a  bundle  of  white 
NEKVES.  fibres),  which  is  placed  between  the  glosso-pharyn- 

geal nucleus  in  front  and  the  spinal-accessory  nucleus  behind,  in 
the  inferior  fovea.  The  fibres,  about  twelve  in  number,  pass 
through  the  medulla,  and  emerge  from  the  restiform  body,  below 
the  glosso-pharyngeal,  and  join  to  form  a  single  nerve.  This 
passes  through  the  foramen  jugulare,  separated  from  the  preceding 
by  a  septum  of  dura  mater,  and  is  distributed  to  the  pharynx, 
larynx,  the  heart  and  lungs,  the  oesophagus  and  stomach. 

ELEVENTH  PAIR  The  spinal  accessory  nerve  is  composed  of  two 
OR  SPINAL  ACCES-  parts  :  an  upper  or  accessory  portion,  which  arises 
SORY  NERVES.  from  the  medulla  below  the  vagus ;  and  a  lower 

or  spinal  portion,  which  arises  from  the  spinal  cord.  The  accessory 
fibres  may  be  traced  to  the  grey  nucleus,  which  is  connected  in 
front  with  the  vagal  nucleus,  and  lies  close  to  the  median  sulcus  of 
the  fourth  ventricle,  extending  to  the  apex  of  the  calamus  scrip- 
torius  and  along  the  side  of  the  central  canal ;  the  spinal  portion 
may  be  traced  below  to  the  tractus  intermedio-lateralis  and  anterior 
cornu,  and  above  to  the  posterior  cornu,  arising  by  slender  fila- 


DISSECTION   OF   THE   BRAIN.  753 

ments  as  low  down  as  the  fifth  or  sixth  cervical  vertebra.  The 
spinal  portion  ascends  behind  the  ligamentum  denticulatum,  through 
the  foramen  magnum,  into  the  skull,  and  joins  the  accessory 
part.  The  nervus  accessorius  then  passes  through  the  foramen 
jugulare  with  the  two  preceding  nerves ;  its  accessory  portion  joins 
the  pneumogastric  nerve,  and  its  spinal  portion  supplies  the 
sterno-mastoid  and  the  trapezius.  The  course  and  distribution  of 
this  nerve  have  been  described  in  the  dissection  of  the  head  and 
neck. 

THE  TWELFTH  The  liypoglossal  nerve  arises  by  several  filaments 

OR  HYPOGLOSSAL  from  the  medulla,  which  emerge  from  the  groove 
NEEVES.  between  the  anterior  pyramid  and  the  olivary 

body.  Its  fibres  may  be  traced  to  a  long  grey  nucleus,  which 
forms  an  eminence  in  the  floor  of  the  fourth  ventricle,  in  front  and 
to  the  inner  side  of  the  vagal  nucleus.  The  filaments  are  collected 
into  two  fasciculi,  which  pierce  the  dura  mater  through  two  aper- 
tures and  join  in  the  anterior  condylar  foramen ;  it  is  distributed 
to  the  muscles  of  the  tongue  and  the  depressor  muscles  of  the  os 
hyoides  and  larynx. 

DISSECTION  OF  The  brain  should  now  be  laid  on  its  base.     We 

THE  BRAIN.  first  notice  a  median  fissure,  separating  the  cere- 

brum into  two  symmetrical  hemispheres :  this  is  the  longitudinal 
fissure.  By  gently  separating  the  hemispheres  we  see  that  the 
fissure  extends  in  front  and  behind  to  the  base,  but  that  in  the 
middle  there  is  at  the  bottom  a  white  band  of  nerve-substance, 
which  is  the  great  transverse  commissure  of  the  cerebrum,  and 
termed  the  corpus  callosum,  upon  which  are  seen  the  two  anterior 
cerebral  arteries. 

Slice  off  the  hemispheres  to  about  half  an  inch  above  the  level 
of  the  corpus  callosurn.  The  cut  white  surface  presents  an  oval 
appearance,  and  is  called  the  centrum  ovale  minus.  The  white 
substance  is  surrounded  by  a  tortuous  layer  of  grey  matter  about 
one-eighth  of  an  inch  in  thickness.  This  grey  substance  consists 
of  four  layers — two  of  grey  alternating  with  two  of  white,  the  most 
external  layer  being  white.  In  some  places,  chiefly  at  the  base  of 
the  brain,  six  layers  have  been  demonstrated.  The  white  substance 
is  spotted  with  red  dots  (puncta  vasculosa)  •  these  are  due  to  the 

3c 


754 


CORPUS   CALLOSUM. 


escape  of  blood  from  the  divided  vessels.  The  corpus  callosum  is 
now  seen  to  be  overlaid  on  each  side  by  the  gyrus  fornicatus ;  the 
border  is  termed  the  labium  cerebri,  and  the  space  between  the 
gyrus  and  the  corpus  callosum  is  called  the  ventricle  of  the  corpus 
callosum. 

Now  slice  off  the  hemisphere  down  to  the  level  of  the  corpus 
callosum,  when  a  section  is  made  of  the  white  substance,  called 
the  centrum  ovale  majus.  The  corpus  callosum  is  now  well 
exposed. 

FIG.  182.  FIG.  183. 


»J       U' 


UPPER  SURFACE  OF  CORPUS 
CALLOSUM. 

1,1.  Lineso  transversae. 

2.  Raphe. 

3,  3.  Anterior  cerebral  a. 


DIAGRAM    OF   LAMINA   CINEREA. 

1.  1.  Peduncles  of  corpus  callosum. 

2.  Lamina  cinerea. 

3.  Commissure  of  optic  nerves. 


CORPUS  This  stratum  of  white  substance,  consisting  of 

CALLOSUM.  transverse  commissural  fibres,  is  the  chief  con- 

necting medium  between  the  two  hemispheres,  and  is  called  the 
great  transverse  commissure  of  the  cerebrum ;  and  moreover,  on 
each  side  forms  the  roof  of  the  lateral  ventricles.  Its  surface  is 
slightly  arched  from  before  backwards ;  it  is  about  four  inches  long 
and  one  inch  in  its  greatest  breadth,  which  is  behind.  Tt  is 
rather  nearer  to  the  front  than  to  the  back  part  of  the  brain,  and 


CORPUS   CALLOSUM. 


755 


it  is  thicker  at  the  ends  than  in  the  middle,  and  thicker  behind 
than  in  front.  A  shallow  groove,  called  the  raphe,  runs  along  the 
middle  of  its  upper  surface  (fig.  182)  ;  in  a  fresh  brain,  two  longi- 
tudinal white  tracts,  named  strice  longitudinales  or  the  nerves  of 
Lancisi,  run  parallel  to  it ;  and  external  to  these  again  are  two 
other  longitudinal  fibres,  strice  longitudinales  later  ales.  The  sur- 
face of  the  corpus  callosum  is  marked  by  transverse  lines  which 
indicate  the  course  of  its  fibres  ;  these  are  the  linece  transversce  of 

FIG.  184. 


Foramen  of  Monro  . 
Middle  commissure  . 
Anterior  commissure 
Lamina  cinerea  .  . 


Optic  nerve 


Pituitary  gland 

Infundibulum 
Tuber  ciuereum 
Corpus  matnmillare 
Locus  perforatus  posticus 


Pons  Varolii 


Velum  interposituTrc. 
Thalamus  opticus. 
Pineal  gland. 
Posterior  commissure. 

Nates. 

Iter  a  tertio  ad  euar- 
tum  ventriculum. 

Valve  of  Vieussens. 
Fourth  ventricle. 


Arachnoid    membra  ne 
(reflected). 


Medulla  oblongata 
VERTICAL   SECTION   THEOUGH   THE    CORPUS   CALLOSUM,    AND    PARTS   BELOW. 

the  old  anatomists.     The  anterior  cerebral  arteries  proceed  along 
the  surface  of  the  corpus  callosum  to  the  back  of  the  brain. 

The  anterior  part  of  the  corpus  callosum  turns  downwards 
and  backwards,  forming  a  bend  called  its  genu.  The  inferior 
part  of  this  bend — rostrum — becomes  gradually  thinner  and  nar- 
rower, and  terminates  in  two  peduncles,  which  diverge  from  each 
other,  and  are  lost,  one  in.  each  fissure  of  Sylvius.  Between  these 

3  c  2 


756  LATERAL   VENTRICLES. 

crura  is  placed  the  lamina  cinerea  (fig.  180).  The  posterior  part 
of  the  corpus  callosum  terminates  in  a  thick,  round  border — the 
splenium — which  is  free,  and  beneath  it  the  pia  mater  enters  the 
interior  of  the  ventricles.  A  satisfactory  view  cannot  be  obtained 
of  the  arch  formed  by  the  corpus  callosum,  of  its  terminations  in 
front  and  behind,  and  of  the  relative  thickness  of  its  different 
parts,  without  making  a  perpendicular  section  through  a  fresh 
brain,  as  shown  in  the  preceding  figure.1 

Connected  with  the  under  surface  of  the  posterior  part  of  the 
corpus  callosum  is  the  fornix,  which  separates  from  it  in  front,  the 
two  structures  being  connected  by  a  vertical  septum — the  septum 
lucidum  (fig.  184). 

LATEEAL  A  longitudinal  incision  should  be  made  on  each 

VENTKICLES.  side  through  the  corpus  callosum  about  half  an 

inch  from  its  median  raphe.  Care  must  be  taken  not  to  cut  too 
near  the  middle  line,  in  order  to  preserve  the  delicate  partition 
which  descends  from  the  under  surface  of  the  corpus  callosum,  and 
separates  the  ventricles  from  each  other.  Two  cavities,  called  the 
lateral  ventricles,  will  thus  be  exposed,  one  in  each  cerebral  hemi- 
sphere, and  they  should  afterwards  be  laid  open  throughout  their 
whole  extent.  Their  general  form  should  be  first  examined  ;  then 
the  several  objects  seen  in  them. 

The  lateral  ventricles  are  two  serous  cavities,  one  in  each  hemi- 
sphere of  the  brain.  They  are  occasioned  by  the  enlargement  and 
folding  backward  of  the  cerebral  lobes  over  the  other  parts  of  the 
central  nervous  axis.  They  contain  a  serous  fluid,  which,  even  in 
a  healthy  brain,  sometimes  exists  in  considerable  quantity ;  when 
greatly  in  excess  it  constitutes  one  form  of  the  disease  termed 
hydrocephalus.  The  ventricles  are  lined  with  ciliated  epithelium, 
laid  upon  a  layer  of  neuroglia  (ependyma)  ;  a  term  which  has  been 
applied  to  that  peculiarly  delicate  connective  tissue  found  through- 
out the  brain  and  spinal  cord. 

The  ventricles  are  crescentic  in  shape,  with  their  backs  towards 

1  The  corpus  callosum  Is  more  or  less  developed  in  all  mammalia,  but  is  absent 
in  birds,  reptiles,  and  fish.  It  has  been  absent  in  the  human  subject  without  any 
particular  mental  deficiency.  See  cases  recorded  by  Eeil,  Archiv  filr  die  Phys.  t. 
xi.,  and  Wenzel,  De  penitiori  Struct.  Cereb.  p.  302. 


LATERAL   VENTRICLES,  757 

each  other.  Each  consists  of  a  central  part  or  body,  and  three 
horns  or  cornua,  anterior,  middle,  and  posterior,  which  extend, 
respectively,  into  the  frontal,  temporo-sphenoidal,  and  occipital 
lobes.  The  body,  situated  in  the  middle  of  the  hemisphere,  is 
triangular  in  shape,  and  is  separated  from  its  fellow  by  the  septum 

FIG.  185. 


VIEW    OF    THE    LATERAL   VENTRICLES    FROM   ABOVE    AFTER    THE    REMOVAL    OF    THE 
CORPUS   CALLOSUM. 

1.  Corpus  striatum.  6.  Hippocampus  major,  with,  the  emi- 

2.  Optic  thalamus.  nentia  collateralis  behind  it. 

3.  Taenia  semicircularis.  7.  The  corpus  callosum  (cut  through). 

4.  Fornix.  8.  Fifth  ventricle. 

5.  Hippocampus  minor.  9.  Pes  Hippocampi. 

10.  Choroid  plexus. 

lucidum.  Its  roof  is  formed  by  the  corpus  callosum  (fig.  186,  i)  ; 
internally,  it  is  bounded  by  the  septum  lucidum  (fig.  184)  ;  on  the 
floor,  beginning  from  the  front,  are  seen  the  corpus  striatum,  the 
tcenia  semicircularis,  the  optic  thalamus,  the  choroid  plexus,  and  the 
corpus  fimbriatum  ofihefornix  (fig.  185). 


758  LATERAL   VENTRICLES. 

The  anterior  horn' extends  into  the  frontal  lobe,  and  as  it  passes 
forwards  it  diverges  slightly  from  its  fellow  of  the  opposite  side. 
It  is  triangular  in  shape,  its  roof  and  anterior  wall  are  formed  by 
the  corpus  callosum,  and  it  curves  round  the  anterior  extremity  of 
the  corpus  striatum. 

The  posterior  horn  can  be  traced  into  the  occipital  lobe,  where 
it  passes  at  first  backwards  and  outwards,  and  then,  narrowing  to 
a  point,  converges  towards  its  fellow.  Its  roof  is  formed  by  the 
fibres  of  the  corpus  callosum  as  they  pass  backwards  and  outwards 

FIG.  186. 


TBANSVEBSE   VEKTICAL   SECTION    THEOUGH   THE   BEAIN. 

1.  Corpus  callosum.  6.  Corpus  mammillare. 

2.  Lateral  ventricle.  7.  Choroid  plexus. 
8.  Third  ventricle.  8.  Fornix. 

4.  Corpus  striatum.  9.  Pituitary  gland. 

5.  Thalamns  opticus. 

from  the  splenium ;  on  its  floor  are  seen  on  the  inner  side  an 
eminence,  the  hippocampus  minor,  and  external  to  it  a  triangular 
flat  surface,  called  the  pes  accessorim  or  eminentia  collateralis.1 

The  middle  or  descending  horn  runs  into  the  temporo-sphenoidal 

1  The  posterior  horns  are  not  always  equally  developed  in  both  hemispheres, 
and  sometimes  they  are  absent  in  one  or  both. 

In  the  carnivora,  ruminantia,  solipeda,  pachydermata,  and  rodentia,  the  lateral 
ventricles  are  prolonged  into  the  largely  developed  olfactory  lobes.  This  is  the 
case  in  the  human  fostus  only  at  an  early  period. 


SEPTUM   LUCIDUM.  759 

lobe,  descends  towards  the  base  of  the  brain,  making  a  curve,  at 
first  backwards  and  outwards,  then  downwards  and  forwards,  and 
lastly  inwards  :  the  initial  letters  of  which  make  the  memorial 
word  '  bodfi.'  Its  roof  is  formed  by  the  fibres  of  the  corpus 
callosum,  partly  by  the  posterior  narrow  extremity  of  the  corpus 
striatum,  with  the  taenia  semicircularis,  and  the  rounded  extremity 
of  the  optic  thalamus.  On  its  floor  are  the  hippocampus  major,  a 
large  rounded  white  eminence  which  follows  the  curve  of  the 
cornu ;  the  pes  hippocampi,  the  expanded  paw-like  extremity  of  the 
former;  the  eminentia  collateralis  on  the  outer  side  of  the  hippo- 
campus major,  and  part  of  which  is  seen  in  the  posterior  horn ; 
the  corpus  fimbriatum  of  the  fornix,  attached  to  the  anterior 
concave  border  of  the  hippocampus  major;  the  fascia  dentata,  a 
crimped  edge  of  grey  matter  under  the  corpus  fimbriatum;  the 
choroid  plexus;  and  the  outer  part  of  the  transverse  fissure. 

The  various  structures  seen  in  the  body  and  horns  of  the  lateral 
ventricle  will  be  described  later  on,  when  they  are  fully  exposed. 

APPEABANCE  ^  a  vertical  transverse  section  is  made  across 

ON  PERPENDICULAB  the  middle  of  the  brain,  the  lateral  ventricles 
SECTION.  would  appear  as  represented  in  fig.  186.  Observe 

that  the  roof  and  the  floor  are  almost  in  actual  contact,  unless 
separated  by  ventricular  fluid.  Together  with  the  third  or  middle 
ventricle,  their  shape  slightly  resembles  the  letter  T.  Such  a 
section  shows  well  the  radiating  fibres  of  the  corpus  callosum,  the 
fornix,  and  the  velum  interpositum  beneath  it ;  also  the  beginning 
of  the  transverse  fissure  at  the  base  of  the  brain,  between  the  crus 
cerebri  and  the  temporo-sphenoidal  lobe. 

If  the  corpus  callosum  be  slightly  raised,  a  thin  vertical  median 
septum,  septum  lucidum,  will  be  seen,  extending  from  the  under 
aspect  of  this  body  to  the  upper  surface  of  the  fornix. 

SEPTUM  This  is  a  thin  and  almost  translucent  partition 

LDCIDUM.  which  descends  vertically  in  the  middle  line  from 

the  under  surface  of  the  corpus  callosum,  and  separates  the  anterior 
part  of  the  lateral  ventricles  from  each  other.  It  is  attached  above 
to  the  corpus  callosum,  below  to  the  reflected  part  of  the  corpus 
callosum  and  fornix  (fig.  184).  It  is  not  of  equal  depth  through- 
out. Its  broadest  part  is  in  front  and  corresponds  with  the  knee 


760 


FIFTH   VENTRICLE. 


of  the  corpus  callosum.  It  becomes  narrower  behind,  tapering  to 
a  thin  point,  where  the  corpus  callosum  and  the  fornix  become 
continuous.  The  septum  consists  of  two  layers,  which  enclose  a 
space  called  the  fifth  ventricle  or  the  ventricle  of  the  septum  (fig. 
185).  Each  layer  consists  of  grey  matter  inside  and  of  white 
matter  outside ;  the  former  representing  the  cortical,  the  latter  the 
medullary  substance  of  the  brain.  The  cavity  is  not  lined  with 
epithelium,  as  is  the  case  with  those  ventricles  developed  from  the 

cerebral  vesicles.1 

FIG.  187. 


DIAGBAM    OF    THE    FOKNIX. 

(The  arrow  is  passed  through  the  foramen  of  Monro). 


1, 1.  Corpora  striata. 

2,  2.  Thalami  optici. 

3,  3.  Anterior  crura  of  fornix  bending  down  to 

join  the  corpora  mammillaria. 

4,  4.  Posterior  crura  of  the  fornix  joining  the  hip- 

pocampi. 


5,  5.  Choroid  plexus. 

6,  6.  Hippocampi  majores. 

7.  Corpus  callosum  cut  through. 

8.  Ventricle  of  septum  lucidum. 


Cut  transversely  through  the  corpus  callosum  about  its  middle, 
with  the  septum  lucidum,  and  turn  forwards  the  anterior  half.  In 
this  way  the  ventricle  of  the  septum  will  be  exposed.  By  turning 
back  the  posterior  half  of  the  corpus  callosum  a  view  is  obtained 
of  the  fornix.  This  proceeding  requires  care,  or  the  fornix  will  be 

1  The  development  of  the  septum  lucidum  commences  about  the  fifth  month  of 
foetal  life,  and  proceeds  from  before  backwards,  pari  passu  with  the  corpus  callosum 
and  the  fornix.  It  is  developed  from  the  lower  part  of  the  great  longitudinal 
fissure,  but  becomes  shut  off  from  it  in  the  process  of  development. 


FORNIX.  761 

reflected  also,  since  these  two  arches  of  nerve-substance  are  here 
so  closely  connected. 

The  fornix  is  a  layer  of  white  matter,  extending 
in  the  form  of  an  arch  (whence  its  name)  from 
before  backwards,  beneath  the  corpus  callosum.  It  is  the  great 
longitudinal  white  commissure,  and  lies  over  the  velum  interposi- 
tum  (fig.  187,  p.  760).  Viewed  from  above,  it  is  triangular  with 
the  base  backwards,  and  is  called  the  body ;  from  its  anterior 
narrow  part  are  given  off  the  two  anterior  crura,  and  from  its  posterior 
and  outer  part  the  two  posterior  crura. 

The  body  is  the  broad  triangular  part  with  the  narrow  portion 
in  front.  The  posterior  broad  part  is  connected  with  the  corpus 
callosum ;  in  front  of  this  it  arches  downwards,  so  as  to  leave  the 
corpus  callosum,  to  which,  however,  it  is  still  connected  by  the 
septum  lucidum.  Its  lateral  free  edges  rest  on  the  choroid 
plexuses,  and  are  seen  on  the  floor  of  the  lateral  ventricles. 

The  anterior  pillars  or  crura  proceed  from  the  front  narrow 
part  of  the  body,  one  on  each  side  of  the  mesial  line.  As  they 
pass  forwards  the  crura  diverge  slightly,  and  descend  through  a 
mass  of  grey  matter  in  the  sides  of  the  third  ventricle  towards  the 
base  of  the  brain,  where,  making  a  sudden  bend  upon  themselves, 
they  form  the  corpora  mammillaria,  from  which  they  may  be  traced 
backwards  and  upwards,  each  to  the  anterior  nucleus  of  the  optic 
thalamus  of  its  own  side.  As  they  descend,  the  anterior  crura  are 
joined  by  the  peduncles  of  the  pineal  body,  by  the  tgenia  semi- 
circularis,  and  by  fibres  from  the  septum  lucidum.  Immediately 
behind  and  below  the  anterior  crura  is  a  triangular  passage,  through 
which  the  choroid  plexuses  of  opposite  sides  are  continuous  with 
each  other.  This  aperture  is  called  the  for  amen  of  Monro.  Strictly 
speaking,  it  is  not  a  foramen,  but  only  an  interval  caused  by  the 
anterior  crus  arching  over  the  groove  between  the  corpus  striatum 
and  optic  thalamus  on  each  side ;  it  establishes  a  communication 
between  the  two  lateral  and  third  ventricles,  and  is  in  shape  like 
the  letter  Y,  the  passage  from  each  lateral  ventricle  passing  down- 
wards and  inwards,  and  meeting  below,  to  be  continued  as  a 
single  passage  for  a  short  distance  before  opening  into  the  third 
ventricle. 


762  CORPUS   STMATUM. 

The  posterior  pillars  or  crura  are  continued  downwards  and  out- 
wards from  the  thickened  free  borders  of  the  body  of  the  fornix, 
and  are  at  first  connected  to  the  under  surface  of  the  corpus 
callosum.  Each  leaves  the  body  at  the  posterior  and  outer  angle 
as  a  thin  flat  white  band  resting  on  the  choroid  plexus  and  the 
pulvinar  of  the  optic  thalamus,  and,  curving  downwards  and  out- 
wards, becomes  intimately  connected  with  the  concave  border  of  the 
hippocampus  major  as  far  down  as  the  pes  hippocampi,  gradually 
tapering  to  a  point  at  its  termination.  The  free  border  of  the 
posterior  crus  is  known  as  the  tcenia  hippocampi  or  the  corpus 
fimbriatum ;  and  on  raising  this  up  we  expose  an  indented  layer 
of  grey  matter,  the  fascia  dentata,  which  is  the  free  border  of  the 
cortical  substance  of  the  cerebrum.1 

The  fornix  should  now  be  cut  through  transversely,  and  its  two 
portions  reflected  backwards  and  forwards  respectively.  On  the 
under  surface  of  the  posterior  portion  are  seen  fibres,  passing 
transversely,  belonging  to  the  corpus  callosum,  and  forming  what 
is  termed  the  lyra. 

Between  the  fornix  and  the  upper  surface  of  the  cerebellum  is 
the  transverse  fissure,  or  fissure  of  Bichat,  through  which  the  pia 
mater  enters  the  ventricles.  The  fissure  extends  from  the  middle 
downwards  on  each  side  to  the  base  of  the  brain,  as  far  as  the  end 
of  the  descending  horn.  It  is  of  a  horse-shoe  shape,  with  the 
concavity  directed  forwards.  The  upper  boundary  of  that  part  of 
the  transverse  fissure  which  extends  into  the  middle  horn  is  some- 
times called  the  free  margin  of  the  hemisphere. 

The  contents  of  the  lateral  ventricles  should  now  be  examined 
more  in  detail. 

CORPUS  The  corpus  striatum  is  so  called  because,  when 

STKIATUM.  cut  into,  it  presents   alternate  layers  of  a  white 

and  grey  substance.  It  is  a  large  ovoid  mass  of  grey  substance, 
part  of  which  forms  an  eminence  in  the  body  of  the  lateral  ventricle 
(the  intra ventricular  portion),  but  the  larger  part  (extra ventricular 
portion)  is  embedded  in  the  white  substance  of  the  cerebrum.  The 

1  The  fornix  and  septum  lucidum  are  absent  in  fish  ;  they  are  merely  rudi- 
mentary in  reptiles  and  birds ;  but  all  mammalia  have  them  in  greater  or  less 
perfection,  according  to  the  degree  of  development  of  the  cerebral  hemispheres. 


CORPUS   STRIATUM. 


763 


intraventricular  portion,  called  the  nucleus  caudatus,  is  pear-shaped, 
broad  in  front,  and  when  traced  backwards  is  found  to  taper 
gradually  to  a  point  on  the  outside  of  the  optic  thalamus  (fig.  188). 
Its  surface  is  of  pinkish-grey  colour,  and  is  crossed  by  numerous 
small  veins  (yence  corporis  striati),  which  open  into  the  vense  Galeni. 

FIG.  188. 


V      W    OF    THE    LATERAL    VENTKICLES   AND    THE    VELUM    INTEBPOSITUM    AFTER 
BEFLECT1NG    THE    FOENIX. 


1.  Anterior  horn. 

2.  Corpus  striatum. 

3.  Tsenia  semicircularis. 

4.  Optic  thalamus. 

5.  Velum  interpositum,  with  the  vense 

Galeni. 

6.  Lyra. 


7.  The  posterior  half  of  the  fornix 

turned  backwards. 

8.  Hippocampus  minor. 

9.  Hippocampus  major. 

10.  Eminentia  collateralis. 

11.  Fifth  ventricle. 

12.  Choroid  plexus. 


When  a  horizontal  cut  is  made  into  it,  it  shows  a  thin  layer  of 
white  substance  covering  a  mass  of  grey  streaked  with  white.  The 
extrdventricular  portion,  or  nucleus  lenticularis,  can  only  be  seen  on 
a  horizontal  section  being  made  outwards ;  the  section  reveals  a 


764  HIPPOCAMPUS   MAJOR. 

biconvex  mass  of  grey  matter,  separated  from  the  nucleus  caudatus 
by  a  broad  band  of  white  substance,  the  internal  capsule,  and  cor- 
responds with  the  island  of  Eeil.  Running  parallel  with  the  outer 
border  of  the  nucleus  lenticularis,  but  separated  from  it  by  a  thin 
layer  of  white  substance,  the  external  capsule,  is  a  wavy  streak  of 
grey  matter,  the  claustrum,  of  variable  thickness.  Outside  the 
claustrum  is  another  layer  of  white  matter,  and  then  we  see  the 
indented  convolutions  of  the  island  of  Reil.  If  a  vertical  trans- 
verse section  be  made  through  the  nucleus  lenticularis,  it  appears 
triangular  and  intersected  by  two  white  lines,  which  divide  it 
into  three  parallel  grey  bands.  Beneath  the  lenticular  nucleus  is 
a  mass  of  grey  matter,  called  the  nucleus  amygdalce,  which  causes 
an  elevation  at  the  apex  of  the  roof  of  the  middle  horn. 

T;ENIA  SEMI-  The  tcenia  semicircularis,  or  stria  terminalis,  is 

CIECULAEIS.  a  narrow  semi-transparent  band  of  longitudinal 

white  fibres,  which  lies  in  the  groove  between  the  corpus  striatum 
and  the  optic  thalamus  (fig.  188).  In  front,  it  is  connected  with 
the  anterior  crus  of  the  fornix,  and  descends  with  it  to  the  corpus 
mammillare ;  it  passes  backwards  and  outwards,  and  behind  it  is 
lost  in  the  white  substance  of  the  middle  horn  of  the  lateral  ven- 
tricle. Several  veins  from  the  corpus  striatum  pass  underneath 
the  taenia  semicircularis  to  join  the  vense  Galeni.  The  upper  surface 
of  the  taenia  is  firmer  in  structure  than  its  deeper  part,  and  is 
called  the  horny  band  of  Tarinus. 

HIPPOCAMPUS  The  hippocampus  major  is  an  elongated  convex 

MAJOR,  eminence  of  grey  matter,  covered  with  white,  and 

is  situated  in  the  posterior  part  of  the  descending  horn.  It  extends 
to  the  bottom  of  the  horn,  following  its  curve,  where  it  becomes 
somewhat  expanded  and  indented  on  the  surface,  so  as  to  resemble 
fehe  paw  of  an  animal,  whence  its  name,  pes  hippocampi.  Attached 
to  the  front  concave  border  of  the  hippocampus  is  the  posterior 
crus  of  the  fornix.  It  corresponds  to  the  hippocampal  fissure, 
which  itself  is  filled  with  grey  matter,  which  forms  the  fascia 
dentata. 

HIPPOCAMPUS  The  hippocampus  minor,  called  also  calcar  avis 

MlNOR-  and  ergot,  is  a  rounded  eminence,  smaller  than  the 

preceding,  occupying  the  inner  curved  wall  of  the  posterior  horn. 


VELUM   INTEKPOSITUM.  765 

It  consists  of  white  matter  externally,  and  corresponds  to  the 
calcarine  fissure.  Between  the  hippocampus  major  and  minor  is  a 
triangular  smooth  surface,  called  the  pes  accessorius,  or  eminentia 
collateralis,  and  is  found  in  the  posterior  and  the  descending  horns. 
This  corresponds  to  the  collateral  fissure. 

VELUM  INTER-    •       The   velum   interpositum,    which    supports   the 
POSITDM  AND  fornix,  should  now  be  examined.     This  is  a  layer 

CHOBOID  PLEXUS.  of  pja  mater,  which  penetrates  into  the  ventricles 
through  the  transverse  fissure,  beneath  the  posterior  border  of  the 
corpus  callosum,  as  shown  in  fig.  184.  The  shape  of  this  vascular 
membrane  is  like  that  of  the  fornix,  and  its  borders  project  beneath 
that  body  and  form  the  red  convoluted  fringes  called  the  choroid 
plexuses.  These  plexuses  consist  almost  entirely  of  tortuous  rami- 
fications of  minute  blood-vessels,  and  are  covered  with  vascular 
villi.  The  villi  themselves  are  covered  with  large  spheroidal 
epithelial  cells.  In  front  the  plexuses  communicate  with  each 
other  through  the  foramen  of  Monro  ;  behind,  they  descend  into 
the  middle  horns  of  the  lateral  ventricles,  and  become  continuous 
with  the  pia  mater  at  the  base  of  the  brain.  From  the  under 
surface  of  the  velum  two  small  vascular  processes  are  prolonged 
into  the  third  ventricle,  forming  the  choroid  plexuses  of  that  cavity. 
Along  the  centre  of  the  velum  run  two  large 
veins,  called  vence  Galeni,  which  return  the  blood 
from  the  ventricles  into  the  straight  sinus. 

The  velum  interpositum,  with  the  choroid  plexuses,  must  now 
be  removed  to  expose  the  following  structures  shown  in  diagram 
(p.  768)  : — 1.  A  full  view  of  the  optic  thalamus.  2.  Between  the 
optic  thalami  is  the  third  ventricle,  a  deep  vertical  fissure,  situated 
in  the  middle  line.  3.  Behind  the  fissure  is  the  pineal  body,  a 
vascular  structure,  about  the  size  of  a  pea.  From  this  body  may 
be  traced  forwards  two  slender  white  cords,  called  its  peduncles,  or 
striae  pineales — one  along  the. inner  side  of  each  optic  thalamus. 
4.  Passing  transversely  across  the  third  ventricle  are  three  coia- 
missures — anterior,  middle,  and  posterior,  connecting  the  opposite 
sides  of  the  brain.  5.  Immediately  behind  the  pineal  body  are 
four  elevations,  two  on  each  side,  called  the  corpora  quadrigemina, 
or  nates  and  testes.  6.  These  bodies  are  connected  with  the  cere- 


766  THALAMUS   OPTICUS. 

bellum  by  two  bands,  one  on  each  side,  termed  the  processus  a 
cerebello  ad  cerebrum.  7.  Between  these  cords  extends  a  thin 
layer  of  grey  substance,  called  the  valve  of  Vieussens,  beneath 
which  lies  the  fourth  ventricle. 

THALAMUS  This,  called  also  the  posterior  cerebral  ganglion, 

OPTICUS.  is   the    convex   oval    elevation    seen  immediately 

behind  the  corpus  striatum  and  taenia  semicircularis.  Superficially 
it  is  covered  with  a  thin  layer  of  white,  but  internally  it  is  com- 
posed of  grey  substance.  The  under  surface  rests  upon  the 
tegmentum  of  the  crus  cerebri,  and  forms  part  of  the  roof  of  the 
middle  horn  of  the  lateral  ventricle  ;  externally  it  is  bounded  by  a 
broad  band  of  white  substance  derived  from  the  crusta,  which 
forms  the  internal  capsule,  already  described.  Externally,  the 
optic  thalamus  is  bounded  by  the  tgenia  semicircularis ;  superfi- 
cially, it  is  covered  by  the  choroid  plexus  and  the  fornix ;  inter- 
nally, it  forms  the  lateral  boundary  of  the  third  ventricle,  and 
has,  running  along  it,  the  peduncle  of  the  pineal  body;  poste- 
riorly, it  overlaps  the  sides  of  the  corpora  quadrigemina  and 
forms  a  prominence  in  the  roof  of  the  middle  horn,  where  it 
receives  the  crus  cerebri.  The  upper  surface  of  the  thalamus  is 
divided  into  two  portions  by  an  oblique  shallow  groove,  passing 
from  before  backwards  ;  the  anterior  and  outer  portion  forms  a 
prominent  convex  surface,  called  the  anterior  tubercle,  which  is 
covered  with  the  epithelium  of  the  lateral  ventricle ;  the  posterior 
and  inner  portion  is  pointed  in  front,  and  posteriorly  enlarges 
to  form  a  prominent  rounded  eminence,  the  posterior  tubercle  or 
pulvinar,  and  is  not  lined  with  epithelium.1  Beneath  the  pos- 
terior part  of  the  thalamus  are  two  small  oval  eminences,  termed 
the  corpora  geniculata,  internum  and  externum.  These  consist  -of 
small  accumulations  of  grey  matter,  beneath  the  white ;  the  outer 
one  being  situated  external  to  and  above  the  internal,  and  to  the 
outer  side  of  one  of  the  roots  of  the  optic  tract  (fig.  180).  From 
each  of  these  bodies  proceeds  a  white  band  to  join  the  root  just 
referred  to,  and  from  the  junction  of  these  three  roots  (brachia) 
the  optic  tract  has  its  commencement.  A  narrow  band  of  white 

1  There  is  a  triangular  depression  between  the  pulvinar  and  the  peduncle  of 
the  pineal  body,  which  has  received  the  name  of  the  trigonum  habenulce* 


COMMISSURES   OF   THE   THIRD   VENTRICLE.  767 

substance  connects  the  external  one  with  the  nates,  and  a  similar 
band  connects  the  internal  one  with  the  testes.1 

THIRD  The  third  ventricle  is  the  long  narrow  fissure 

VENTRICLE.  between  the  optic  thalami,  and  reaches  down  to 

the  base  of  the  brain.  Its  roof  is  formed  by  the  fornix  and  the 
velum  interpositum,  the  under  aspect  of  which  is  lined  by  the 
epithelium  covering  the  general  ventricular  cavities,  and  is  re- 
flected from  the  velum  and  choroid  plexuses  on  to  the  optic 
thalami ;  the  floor,  which  increases  in  depth  in  front,  is  formed  by 
certain  parts  at  the  base  of  the  brain,  found  within  the  inter- 
peduncular  space — viz.  the  locus  perforatus  posticus,  corpora  mam- 
millaria,  tuber  cinereum,  infundibulum,  and  lamina  cinerea,  all  of 
which  are  best  seen  in  a  vertical  section,  as  shown  on  page  755. 
In  front,  it  is  bounded  by  the  anterior  crura  of  the  fornix  and 
the  anterior  commissure  ;  laterally,  by  the  optic  thalami  and  the 
peduncles  of  the  pineal  body ;  behind,  by  the  posterior  commissure 
and  the  iter  a  tertio  ad  quartum  ventriculum,  which  is  a  long  canal 
beneath  the  corpora  quadrigemina,  connecting  the  third  with  the 
fourth  ventricle. 

Passing  across  the  third  ventricle  are  seen  three 
COMMISSURES.  .  , ,  .  .  -.  ,,  -. 

commissures,  the  anterior,  middle,  and  posterior. 

The   middle   commissure   may  be    seen   by  gently  separating   the 

optic  thalami,  and  is  about  half  an  inch  in  breadth. 

This  is  composed  entirely  of  grey  substance,  and 

in  most  brains,  owing  to  its  softness,  is  generally  torn  before  it 

can  be  examined.2     The  anterior  commissure  is  a  round  white  cord, 

which  lies  immediately  in  front  of  the  anterior 
ANTERIOR.  /.    ,••        f  -,  ,-, 

crura  or   the    tornix,   and   connects   the   corpora 

striata.  This  commissure  may  be  traced  on  each  side,  through  the 
corpora  striata,  below  the  nuclei  lenticulares,  extending  backwards 
far  into  the  temporo-sphenoidal  lobes.  Situated  immediately  in 

1  These  bands  are  faintly  marked  in  man,  but  are  more  apparent  in  the  lower 
animals. 

2  The  soft  commissure  does  not  appear  to  be  a  very  essential  constituent  part 
of  the  brain.   It  is  not  found  before  the  ninth  month  of  foetal  life,  and  in  seme 
instances,  according  to  our  observations,  is  never  developed.     Wenzel  states  that 
it  is  absent  in  about  one  out  of  seven  subjects  (De  penitiori  Struct.  Cerebri  Horn, 
et  Brut.    Tubingen,  1812). 


768  THIRD   VENTRICLE. 

front  of,  and   rather   below   the   pineal  body,  is 
another  thin  round  white  cord  called  the  posterior 
Its  fibres  pass  into  the  substance  of  the  hemispheres 
and  connect  the  optic  thalami.     Its  fibres  are  derived  from  the 
fillet  which  comes  from  the  tegmentum  of  the  crus  cerebri. 

FIG.  189. 


POSTERIOR. 
commissure. 


Corpus  callosum  cut  through  .    . 

Ventricle  of  the  septum  lucidum  . 
Corpus  striatum 

Anterior  crura  of  the  fornix     .    . 

Anterior  commissure 

Tsenia  semicircularis 

Middle  commissure 

Thalamus  opticus 

Crura  of  pineal  gland 

Posterior  commissure 

Pineal  gland 


Corp.  quadrigemina 


Nates 


I  Testes  . 

Valve  of  Vieussens 

P rocessus  a  cerebello  ad  cerebrum . 


8  E 


The  third  ventricle  communicates  with  the  lateral  ventricles  by 
the  two  openings  of  the  foramina  of  Monro,  with  the  fourth  ven- 
tricle through  the  iter  a  tertio  ad  quartum  ventriculum,  and"  in 
front  of  its  floor  by  a  conical  cavity,  iter  ad  infundibulum,  with  the 
infundibulum. 

The  third  ventricle  is  covered  with  an  epithelial  lining  con- 
tinuous with  that  of  the  lateral  ventricles  through  the  foramina 


CORPORA   QUADRIGEMINA.  769 

of  Monro ;  after  covering  the  walls  of  the  third  ventricle  it  lines 
the  aqueduct  of  Sylvius  to  pass  to  the  fourth  ventricle. 

PINEAL  BODY  The  pineal  body  (conarium)  is  a  very  vascular 

OE  GLAND.  oval  body,  situated  immediately  in  front  of  the 

corpora  quadrigemina  (fig.  189).  It  is  about  the  size  of  a  cherry- 
stone, and  is  firmly  connected  with  the  under  surface  of  the  velum, 
and  is  apt  to  be  separated  from  its  normal  position  when  that 
membrane  is  reflected.  It  is  connected  to  the  cerebrum  by  two 
white  crura,  the  peduncles  of  the  pineal  body,  which  extend  for- 
wards, one  on  the  inner  side  of  each  optic  thalamus  along  their 
upper  margin,  and  terminate  by  joining  the  anterior  crura  of 
the  fornix.  The  peduncles  join  together  behind  in  front  of  the 
pineal  body,  and  are  connected  with  the  front  of  the  posterior 
commissure. 

The  pineal  body  consists  of  numerous  small  follicles  filled  with 
cells,  which  are  separated  by  connective  tissue ;  so  that  in  struc- 
ture it  much  resembles  that  of  the  anterior  lobe  of  the  pituitary 
body.  In  its  interior  it  contains,  besides  some  viscid  fluid,  more  or 
less  gritty  particles  (acervulus  cerebri),  consisting  of  phosphate  and 
carbonate  of  lime  and  phosphate  of  magnesia  and  ammonia.  Be- 
sides the  calcareous  particles,  these  follicles  contain  corpora  amy- 
lacea ;  and,  when  abundant,  this  sabulous  matter  is  found  on  the 
peduncles  of  the  pineal  body. 

The  pineal  body  is  larger  in  the  female  than  in  the  male 
subject,  and  is  largest  of  all  in  the  child.  It  is  found  in  all 
mammalia,  birds,  and  reptiles,  in  the  same  typical  position,  but 
its  functions  are  entirely  unknown. 

CORPOBA  QUA-  The  corpora  quadrigemina  are  four  round  emi- 

DEIGEMINA.  nences,  situated  two   on   each   side,  behind   the 

pineal  body,  and  are  separated  from  each  other  by  a  crucial  depres- 
sion. Though  white  on  their  surface,  they  contain  grey  matter  in 
their  interior  for  the  purpose  of  giving  origin  to  the  optic  tract. 
Laterally,  they  are  continued  outwards  as  two  convex  white  cords, 
the  anterior  and  posterior  brachia.  The  anterior  brachium  passes 
between  the  corpora  geniculata,  and  is  continued  on  into  the  optic 
tract,  of  which  it  may  be  considered  its  direct  root :  the  posterior 
brachium  passes  forwards  and  outwards,  and  is  lost  beneath  the 

3D 


770  VALVE    OF   VIEUSSENS. 

corpus  geniculatum  internum.  They  are  situated  above  the  iter  a 
tertio  ad  quartum  ventriculum.  The  anterior  pair  are  called  the 
nates,  and  are  larger  and  darker  than  the  posterior  pair,  which  take 
the  name  of  testes.  A  more  appropriate  term  for  these  bodies 
would  be  the  optic  lobes.1 

The  corpora  quadrigemina  are  developed  very  early  in  foetal  life, 
and  are  at  first  only  two  in  number,  one  on  each  side  of  the 
mesial  line;  but  about  the  seventh  month  a  transverse  groove  is 
apparent,  thus  mapping  out  the  four  bodies.2 

PBOCESSUS  A  B7  gently  drawing  back  the  overlapping  cere- 

CEEEBELLO  AD  bellum,  two  broad  white  cords  are  seen,  which 
CEBEBKUM.  -pass  backwards,  diverging  from  each  other,  from 

the  optic  thalami  and  the  corpora  quadrigemina  to  the  cerebellum 
(fig.  189).  These  are  the  processus  a  cerebello  ad  cerebrum,  or  supe- 
rior peduncles  of  the  cerebellum.  They  connect  the  cerebrum  and 
cerebellum,  and  rest  upon  the  crura  cerebri.  Below  they  pass  to 
the  inferior  vermiform  process  and  to  the  white  matter  within  the 
corpus  dentatum. 

VALVE  OF  The  triangular  space  between  the  superior  pe- 

VIEUSSENS.  duncles  is  occupied  by  a  thin  layer  of  grey  matter, 

which  covers  over  the  anterior  part  of  the  fourth  ventricle.  This 
layer  is  called  the  valve  of  Vieussens,  or  the  anterior  or  superior 
medullary  velum ;  it  is  narrow  in  front  and  broad  posteriorly,  where 
it  is  connected  with  the  central  portion  of  the  cerebellum.  Along 
the  mesial  line  of  its  upper  surface  there  is  an  irregular  ridge,  the 
frcewuhem,  which  becomes  lost  towards  its  lower  part ;  the  lower 

1  Eminences  homologous  to  the  corpora  quadrigemina  are  found  in  all  verte- 
brate animals ;  they  are  the  mesocephalic  lobes ;  they  always  give  origin  to  the 
optic  nerves,  and  their  size  bears  a  direct  relation  to  the  power  of  sight.     They  are 
relatively  smaller  in  man  than  in  any  other  animal.     In  birds  there  are  only  two 
eminences,  and  these  are  very  large,  especially  in  those  far-seeing  birds  which  fly 
high,  as  the  eagle,  falcon,  vulture,  &c.,  who  require  acute  sight  to  discern  their  prey 
at  a  distance. 

2  On  making  a  transverse  vertical  section  through  the  nates,  we  find  that  there 
is  a  superficial  thin  layer  of  white  fibres  (stratum  zonale)  ;    beneath  this  is  a 
crescentic  layer  of  grey  matter  (stratum  cinereum) ;  deeper  than  this  is  a  thick 
biconvex  mass  of  grey  matter,  with  nerve  filaments  and  nerve  cells  (stratum 
opticum) ;  and  lowest  of  all  is  an  arched  layer  of  white  nerve  fibres  derived  from 
the  fillet  (stratum  lemnisci). 


FOURTH   VENTRICLE.  771 

part  is  overlapped  by  a  corrugated  lobule  of  grey  matter  from 
the  anterior  part  of  the  cerebellum,  and  is  called  the  linguetta 
laminosa. 

The  third  ventricle  is  connected  with  the  fourth 
AD  QUARTUM  ^v  a  canal,  large  enough  to  admit  a  probe,  which 

VENTBICULUM,  runs  downwards  and  backwards  beneath  the  pos- 

OR  AQUEDUCT  terior  commissure  and  the  corpora  quadrigemina. 

It  is  about  half  an  inch  in  length,  and  its  shape 
varies  in  different  parts  of  its  course  :  in  the  lower  being  T-shaped,  • 
and  in  the  upper  part  shield-shaped,  on  transverse  section.  In  its 
walls  is  a  large  amount  of  grey  matter,  in  which  are  the  nuclei  of 
origin  of  the  third,  fourth,  and  upper  part  of  the  fifth  cranial 
nerves.  It  is  lined  with  ciliated  columnar  epithelium.  This  pas- 
sage, together  with  the  third  and  fourth  ventricles,  are  persistent 
parts  of  the  central  canal,  which  in  early  fcetal  life  extended  down 
the  middle  of  the  cerebro-spinal  axis.  It  subsequently  becomes 
much  encroached  upon  by  the  large  increase  of  grey  substance  in 
the  process  of  development. 

FOURTH  The  fourth  ventricle  is  the  space  situated  be- 

VENTRICLE.  t     n  the  cereba  Hum   behind    and    the  posterior 

surface  of  the  medulla  oblongata  and  pons  Varolii  in  front.  It  is 
the  dilated  portion  of  the  primordial  canal  alluded  to  in  the  last 
paragraph.  If  viewed  in  a  vertical  section,  as  represented  in  the 
diagram  (fig.  184),  it  appears  triangular,  with  its  base  forwards  ; 
but  if  seen  from  behind,  it  is  a  lozenge-shaped  space,  the  long  axis 
being  antero-posterior  (fig.  190). 

The  upper  wall  or  roof  of  the  fourth  ventricle  is  formed  by  the 
valve  of  Vieussens,  and  by  the  front  of  the  inferior  vermiform  process, 
with  the  two  amygdalae ;  laterally  it  is  bounded,  in  front  by  the 
processus  a  cerebello  ad  cerebrum,  and  behind  by  the  diverging 
posterior  pyramids  and  restiform  bodies ;  below,  by  the  continua- 
tion of  the  arachnoid  membrane  on  to  the  posterior  surface  of  the 
spinal  cord,  in  which  there  is  an  aperture  called  the  foramen  of 
Magendie ;  in  front  its  floor  is  formed  by  the  medulla  oblongata 
and  pons  Varolii.  The  pia  mater  is  prolonged  for  a  short  distance 
into  the  lower  part  of  the  cavity,  and  forms  the  choroid  plexus  of 
the  fourth  ventricle. 


772 


FOURTH   VENTRICLE. 


The  anterior  wall  is  diamond-shaped,  pointed  above  and  below, 
while  laterally  the  space  broadens  out  into  an  angular  point,  be- 
tween the  cerebellum  and  the  medulla,  called  the  lateral  recess. 
Below,  the  ventricle  is  bounded  by  the  restiform  bodies  and  poste- 
rior pyramids  diverging  like  the  branches  of  the  letter  V  to  form 
the  inferior  peduncles  of  the  cerebellum ;  the  divergence  of  these 
cords,  with  the  median  furrow,  was  called  by  the  older  anatomists 
the  calamus  scriptorius,  from  its  fancied  resemblance  to  a  writing 
pen.  At  the  termination  of  the  posterior  pyramid  there  is  a  slight 
overhanging  thickening,  turning  over  the  restiform  body  at  the 

FIG.  190. 


-a.  Processus  a  cerebello 
ad  cerebrum. 

6.  Restiform  bodies. 

c.  Fasciculi  graciles. 

•d.  Fasciculus  teres,  ex- 
ternally is  the  f ovea 
superior. 


e.  Medullary  strife. 
/.  Fasciculus  tores. 
g.  Tuberculum  acusti- 

cum. 

h.  Fovea  inferior. 
i.  Cerebellum. 


FLOOR  OF  THE  FOURTH  VENTRICLE. 

lateral  recess,  of  which  it  forms  the  lateral  boundary ;  it  is  called 
the  ligula  or  tcenia.  We  find  also  a  similar  thickening,  partly  of 
the  lining  membrane  and  partly  of  nerve-matter,  arching  over 
the  apex  of  the  calamus  scriptorius,  known  as  the  obex.1 

The  floor,  formed  by  the  posterior  surface  of  the  medulla  and 
pons,  is  marked  by  a  median  groove  passing  from  the  apex  of  the 
calamus  scriptorius  to  the  iter.  It  is  divided  into  two  portions,  a 
lower  and  an  upper,  by  some  transverse  white  fibres  called  the 
strice  acusticce  or  medullares,  which  emerge  from  the  median  groove 
and  pass  outwards  over  the  inferior  cerebellar  peduncle  to  join  part 

1  Obex,  a  bar. 


STRUCTURE  OF  THE  CEREBRUM.  773 

of  the  roots  of  the  auditory  nerves.  The  lower  part  of  the  floorv 
on  each  side,  is  mapped  out  into  three  surfaces  by  a  triangular 
depression,  fovea  inferior  (fig.  190,  /i),  having  its  apex  at  the  trans- 
verse strife,  and  its  base  below  at  the  posterior  pyramids.  On  the 
outer  side  of  the  fovea,  there  is  a  convex  triangular  surface,  with 
its  base  upwards  (fig.  190,  g),  called  the  tubercuhim  acusticum;  on 
the  inner  side  of  the  fovea,  and  bounded  internally  by  the  median 
groove,  is  the  rounded  triangular  surface  which  marks  the  com- 
mencement of  the  fasciculus  teres.  Towards  the  base  of  the  infe- 
rior fovea  there  is  a  dark  surface  of  grey  matter  called  the  ala 
cinerea,  which  becomes  raised  into  an  eminence  (eminentia  cinerea). 

The  upper  part  of  the  fourth  ventricle  is  that  portion  between 
the  acoustic  striee  and  the  iter  a  tertio  ad  quartum  ventriculum. 
The  median  groove  is  still  continued  upwards,  although  it  becomes 
fainter,  and  on  each  side  of  it  is  the  parallel  rounded  eminence,  the 
fasciculus  teres.  Outside  this  fasciculus  is  a  triangular  depres- 
sion, the  fovea  superior ;  and  passing  upwards  under  cover  of  the 
superior  cerebellar  peduncle,  we  notice  a  depression  of  grey  sub- 
stance, called  the  locus  cceruleus. 

The  lower  part  of  the  fourth  ventricle  is  developed  from  the 
metencephalic,  the  upper  part  from  the  epencephalic,  portion  of  the 
posterior  primary  vesicle.1 

STRUCTURE  OF  The  white  substance  of  the  cerebrum  consists 

THE  CEKEBKUM.  of  medullated  fibres,  which  are,  as  a  rule,  smaller 
than  those  in  the  spinal  cord.  The  general  arrangement  of  the 
fibres  may  be  classified  under  three  heads :  1 .  The  diverging  or 
peduncular  fibres.  2.  The  transverse  commissural  fibres;  and, 
3.  The  longitudinal  fibres. 

The  diverging  or  peduncular  fibres  are  derived  partly  from  the 
crusta,  and  partly  from  the  tegmentum  of  the  crus  cerebri.  Those 
from  the  crusta  pass  forwards  and  outwards  between  the  nucleus 
caudatus  and  nucleus  lenticularis  with  the  internal  capsule,  and  in 

1  Tiedemann  proposed  to  call  the  fourth  ventricle  the  first,  because  in  the 
foetus  it  is  formed  sooner  than  any  of  the  others ;  because  it  exists  in  all  verte- 
brated  animals,  whereas  the  lateral  ventricles  are  absent  in  all  osseous  fishes  ;  and 
because  the  ventricle  of  the  septum  lucidum  is  absent  in  all  fishes,  in  reptiles,  and 
in  birds. 


774  THE   CEREBELLUM. 

front  of  these  ganglia  the  fibres  radiate  outwards  in  all  directions, 
called  the  corona  radiata.  Most  of  these  fibres  pass  indirectly 
to  the  cortical  portion  of  the  cerebrum ;  some  proceed  direct  to  the 
cortex,  through  the  grey  ganglionic  structure,  amongst  which  are 
the  pyramidal  tract,  passing  to  the  grey  matter  in  the  neighbour- 
hood of  the  fissure  of  Rolando,  and  the  direct  sensory  tract  to  the 
cortex  of  the  occipital  lobe.  The  fibres  from  the  tegmentum  are 
joined  by  others  from  the  processus  a  cerebello  ad  cerebrum,  and 
the  corpora  quadrigemina,  and  pass  under  the  optic  thalamus,  and 
probably  through  this  body,  and  radiate  outwards,  joining  the  corona 
radiata  to  proceed  to  the  temporo-sphenoidal,  post-parietal,  and 
occipital  lobes. 

The  transverse  commissural  fibres  connect  the  two  hemispheres, 
and  are  the  corpus  callosum,  the  anterior  and  posterior  commissures. 

The  longitudinal  fibres  consist  of  the  fornix,  the  striae  longitudi- 
nales  of  the  corpus  callosum,  the  taenias  semicirculares,  the  gyrus 
fornicatus,  the  gyrus  uncinatus,  and  the  peduncles  of  the  pineal 
body. 


THE   CEBEBELLUM. 

The  cerebellum  is  that  portion  of  the  encephalon  situated  in  the 
occipital  fossa,  beneath  the  posterior  lobes  of  the  cerebrum,  from 
which  it  is  separated  by  the  tentorium.  It  measures  in  its  trans- 
verse diameter  from  three  and  a  half  to  four  inches,  in  its  antero- 
posterior  diameter  two  to  two  and  a  half  inches,  and  two  inches  in 
its  vertical  diameter.  Its  form  is  ellipsoidal,  with  the  long  axis 
transverse.  When  the  arachnoid  membrane  and  the  pia  mater  are 
removed,  it  is  noticed  that  its  surface  is  darker,  and  not  arranged 
in  tortuous  convolutions  like  those  of  the  cerebrum.  It  is  covered 
externally  with  grey  matter,  and  consists  of  a  multitude  of  thin 
laminae  disposed  in  a  series  of  nearly  parallel  concentric  curves, 
with  the  concavity  forwards.  By  a  little  dissection  it  is  easy  to 
separate  some  of  the  laminae  from  each  other,  and  to  see  that  the 
intervening  fissures  increase  in  depth  from  the  centre  towards  the 
circumference. 


THE   CEREBELLUM.  775 

The  cerebellum  consists  of  two  lateral  hemispheres  united  by 
an  intermediate  portion,  the  vermiform  process,  the  upper  aspect 
of  which  takes  the  name  of  the  superior  vermiform,  process,  the 
inferior  that  of  the  inferior  vermiform  process.  Comparative 
anatomy  proves  that  this  is  the  fundamental  part  of  the  cere- 
bellum, the  lateral  masses  not  being  developed  in  the  vertebrate 
series  until  after  the  birds.  In  man  the  lateral  masses  form  by  far 
the  largest  part  of  the  cerebellum. 

The  two  hemispheres  on  their  under  aspect  are  convex  and 
separated  from  each  other  by  a  deep  fossa,  the  vallecula-,  and, 

FIG.  191. 


SUPERIOR  SURFACE  OF  THE  CEREBELLUM. 

i  c  s.  Incisura  cerebelli  anterior.  p  i.  The  posterior  inferior  lobe. 

i  cp.  Incisura  cerebelli  posterior.  hf.  The  great  horizontal  fissure. 

as  or  I  q.  The  anterior  superior  or  quad-  I  c.  The  lobulus  centralis. 

rate  lobe.  m  c.  Monticulus  cerebelli. 

p  s.  The  posterior  superior  lobe.  c  i.  Commissura  simplex. 


behind,  this  is  continued  so  as  to  form  a  deep  notch  between  the 
posterior  borders  of  the  cerebellum. 

The  upper  surface  is  separated  from  the  lower  by  a  deep  fissure 
named  the  great  horizontal,  which  extends  along  the  free  border  of 
each  hemisphere. 

The  upper  surface  of  the  cerebellum  slopes  on 
UPPER  SURFACE.  ,       .-,      ,  .,         ,  ,  . ,  ni     ,. 

each,  side,  having  a  ridge  along  the  middle  line, 

called  the  superior  vermiform  process.  This  process  presents  three 
eminences,  an  anterior,  middle,  and  posterior,  which  are  named 
respectively,  the  lobulus  centralis,  the  monticulus  cerebelli,  and  the 


776  THE   CEEEBELLUM. 

commissura  simplex.  The  hemispheres  are  separated  posteriorly  by 
a  deep  notch,  the  incisura  cerebelli  posterior,  which  receives  the  falx 
cerebelli;  and  anteriorly  by  a  broader  notch,  the  incisura  cerebelli 
anterior,  which  lodges  the  pons  Varolii.  On  this  surface  of  the 
cerebellum  are  two  lobes,  one  of  which,  the  quadrate,  is  situated  on 
its  external  and  anterior  aspect ;  the  other,  the  posterior  or  cres- 
centic,  is  placed  along  its  posterior  border. 

On  the  under  surface  of  the  cerebellum,  its  divi- 
UNDER  SURFACE.       ...  ,         .      ,  . 

sion  into  two  hemispheres  is  clearly  perceptible. 

The  deep  furrow  between  them  is  called  the  vallecula.  The  front 
part  of  it  is  occupied  by  the  medulla  oblongata.  To  examine  the 
surface  of  the  valley,  the  medulla  must  be  raised,  and  the  hemi- 
spheres separated  from  each  other.  Along  the  middle  line  of 
the  vallecula  is  the  inferior  vermiform  process,  which  is  the  under 
surface  of  the  original  part  of  the  cerebellum.  Traced  forwards, 
this  process  terminates  in  the  nodule,  which  projects  into  the  fourth 
ventricle,  and  is  called  the  laminated  tubercle  of  Malacarne  ;  traced 
backwards,  it  ends  in  a  small  conical  projection,  called  the  pyramid ; 
between  these  is  a  tongue-like  body,  called  the  uvula,  which  is  con- 
nected with  the  adjacent  amygdalge  by  an  indented  grey  ridge, 
named  the  furrowed  band.  Passing  from  the  nodule  to  the  flocculus 
is  a  thin  valve-like  fold  of  white  matter,  which  together  take  the 
name  of  the  posterior  or  inferior  medullary  velum.  Its  anterior 
crescentic  margin  is  free,  and  its  posterior  is  attached  to  the 
furrowed  band.1  To  see  this  satisfactorily,  the  tonsils  must  be 
carefully  separated  from  each  other. 

Each  hemisphere  presents  on  its  under  surface  certain 
secondary  lobes,  to  which  different  names  have  been  applied  (fig. 
192).  That  portion  which  immediately  overlies  the  side  of  the 
vallecula  is  called  the  tonsil  (amygdala)  •  this  is  connected  with 
the  uvula  by  an  indented  layer  of  grey  matter,  called  the  furrowed 
band.  At  the  anterior  part  of  each  hemisphere,  near  the  middle 
line,  is  a  little  lobe  named  the  flocculus  or  subpeduncular  lobe. 

In  addition  to  the  amygdalae  and  flocculi,  already  mentioned, 
other  lobes  have  been  described  on  the  under  surface  of  the  cere- 
bellum. Thus,  there  is  the  digastric  lobe,  situated  external  to  the 
1  These  are  sometimes  called  the  valves  of  Tarini. 


THE   CEREBELLUM.  777 

amygdala ;  and  behind  this  are  successively  the  slender  and  the 
posterior  inferior  lobes  (fig.  192). 

PEDUNCLES  OF  The  cerebellum  is  connected  with  the  cerebro- 

THE  CEREBELLUM,  spinal  axis  by  three  peduncles  or  crura —  a  superior, 
middle,  and  inferior.  With  the  medulla  oblongata  it  is  connected 
by  means  of  the  restiform  tracts;  these  are  called  the  processus  a 
cerebello  ad  medullam,  or  its  inferior  peduncles  :  with  the  cerebrum 
it  is  connected  by  means  of  the  processus  e  cerebello  ad  cerebrum  • 
these  are  called  its  superior  peduncles.  The  lateral  portions  of  the 
pons  constitute  its  middle  peduncles. 

FIG.  192. 


INFERIOR    SURFACE    OF    THE    CEREBELLUM. 

A.  The  amygdala.  fl.  The  flocculus. 

Bi.  The  biventral  lobe.  n.  The  nodule       \ 

G.  The  slender  lobe.  u.  The  uvula         !•  situated  in  the  vallecula. 

pi.  The  posterior  inferior  lobe.  p.  The  pyramid     > 
hf.  The  great  horizontal  fissure. 

INTERNAL  To  examine  the  internal  structure  of  the  cere- 

STRUCTURE.  bellum,    a    longitudinal    section   must    be    made 

through  the  thickest  part  of  one  of  its  hemispheres.  There  is  then 
seen  in  the  centre  a  large  nucleus  of  white  substance,  from  which 
branches  radiate  into  the  grey  substance  in  all  directions,  and 
upon  which  the  grey  cortical  substance  is  deposited  (laminai). 

The  lamince,  about  twelve  in  number,  have  branches  from  them 
at  right  angles,  secondary  laminae ;  and,  from  these  again,  tertiary 


778 


THE    CEREBELLUM. 


FUNCTIONS. 


laminae.  This  racemose  arrangement  of  the  white  matter  in  the 
substance  of  the  grey  has  been  likened  to  the  branches  of  a  tree 
deprived  of  its  leaves,  and  is  generally  known  as  the  arbor  vitce. 

COKPUS  DEN-  In  the  centre  of  the  white  substance  of  each 

TATUM.  hemisphere  is  a  nucleus  of  grey  matter,  the  cwpus 

dentatum,  consisting  of  a  zigzag  line  of  yellowish-grey  colour, 
incomplete  at  its  upper  and  inner  part,  and  enclosing  within  it 
some  white  substance.  Prom  its  centre  white  fibres  may  be  traced 
to  the  superior  cerebellar  peduncles  and  the  valve  of  Vieussens. 
It  is  displayed  either  by  a  vertical  or  by  a  horizontal  section. 

Respecting  the  function  of  the  cerebellum,  the 
deductions  derived  from  comparative  anatomy 
and  physiological  experiments  render  it  probable  that  it  is  the 
co-ordinator  of  muscular  movements — e.g.,  in  walking,  flying,  and 
swimming. 

The  encephalon  is  originally  developed  from  three  primary 
vesicles,  from  which  the  following  parts  are,  in  the  later  stages, 
severally  developed : — 

j  Cerebral       hemispheres,       corpora 

.Prosencephalon       -j      striata,  corpus   callosum,  fornix, 

1.   Anterior  \     lateral  ventricles,  olfactory  lobe. 

vesicle  /Optic  thalami,    pineal  body,  pitui- 

^Thalamencephalon  J      tary  body,  third  ventricle,  optic 


2.  Middle 
vesicle 


3.  Posterior 
vesicle 


j  Mesencephalon 


I  Epencephalon 


\  Metencephalon 


(Corpora  quadrigemina,  crura  cere- 
bri,  aqueduct  of  Sylvius,  optic 
nerve. 

[  Cerebellum,  pons  Varolii,  front  part 
j      of  the  fourth  ventricle. 
/Medulla  oblongata,   posterior   part 
J      of  the  fourth  ventricle,  auditory 


nerve. 


The  component  parts  of  the  encephalon  begin  to  be  developed 
at  different  periods  of  foetal  life,  and  the  ages  at  which  they 
severally  begin  to  appear  are  given  as  follows  : — 


DEVELOPMENT   FROM   THE   CEREBRAL   VESICLES. 


779 


Metencephalon . 


Epencephalon  : 


Mesencephalon . 


POSTERIOR  VESICLE. 

Part  Month 

Medulla  oblongata       .  Third 

Restiform  bodies         .  Third  to  fourth 

Anterior  pyramids      .  Fifth 

Olivary  bodies     .         .  Sixth 

Strise  acusticse     .          .  After  birth 

Cerebellum          .         .  Second,  end  of 

Inf.  cerebellar  ped.      .  Third 

Middle       „         „        .  Fourth 

Corpus  dentatum        .  Fourth 

Superior  cereb.  ped.     .  Fifth 

Valve  of  Vieussens     .  Fifth 

Lobes  of  cerebellum    .  Fifth 

Folia  .         .  •       .         .  Sixth 

Flocculus    .         .         .  Seventh 

Post,  medullary  velum  Seventh 

Amygdalae .         .         .  Eighth 

MIDDLE  VESICLE. 

Corpora  quadrigemina  Fourth 

Fillet          .         .         .  Fourth 
Corpora  quadrig.  : 

Vertical  groove        .  Sixth 

Transverse  Seventh 


Thalamencephalon 


Prosencephalon 


ANTERIOR  VESICLE. 

Optic  thalami 
Anterior  commissure  . 
Posterior  commissure  . 
Pineal  body 
Optic  tracts 
Peduncles     of     pineal 

body 

Middle  commissure     . 
Island  of  Reil    . 
Corpora  striata  . 
Corpus  callosum 


Second  to  third 
Third 

Third,  end  of 
Third  to  fourth 
Third  to  fourth 

Third  to  fourth 
Ninth  1 
Earliest  of  all 
Third 
Third,  end  of 


780 


DISSECTION   OF   THE   SPINAL   CORD. 


Prosencephalon . 
(cont.) 


Part 

Fornix    . 
Sulci,  primitive  : 

Fissure  of  Sylvius  . 

Parieto-occipital 

Dentate  . 

Calcarine 
Sulci,  secondary  : 

Rolando . 

Parallel  . 

Interparietal  . 

Calloso-marginal 

Collateral 

Frontal  . 

Hippocampus  major    . 
Convolutions 
Convolutions  develope 

rapidly    . 
Septum  luciclum 


Month 
Fourth  to  fifth 

Middle  of  third 

Third 

Third 

Third 

Fifth  to  sixth 
Fifth 

Sixth,  end  of 
Sixth,  end  of 
Sixth,  end  of 
Seventh 
Fourth  to  fifth 
Fourth  to  fifth 

Seventh  to  eighth 
Fifth 


The  cerebral  hemispheres  enlarge  at  first  slowly,  but  later  they 
develope  much  more  rapidly ;  the  extent  to  which  they  reach 
backwards  in  the  various  periods  of  intra-uterine  life  is  as 
follows : — 

To  the  optic  thalami  at  third  month, 

To  the  corpora  quadrigemina  at  fourth  month, 

To  the  greater  part  of  cerebellum  at  sixth  month, 

To  the  posterior  border  of  cerebellum  at  seventh  month. 


DISSECTION   OF   THE    SPINAL   COED. 

To  examine,  in  situ,  the  spinal  cord  covered  with  its  mem- 
branes, the  arches  of  the  vertebrae  must  be  sawn  through,  and 
removed.  It  is  then  noticed  that  the  cord  does  not  occupy  the 
whole  cavity  of  the  spinal  canal.  The  dura  mater  does  not  adhere 
to  the  vertebras,  and  does  not  form  their  internal  periosteum,  as  in 
the  skull.  Between  the  bones  and  this  membrane,  a  space  inter- 


SPINAL   VEINS. 


781 


venes,  which  is  filled  with  a  soft  reddish-looking  fat,  with  watery 
cellular  tissue,  and  the  ramifications  of  a  plexus  of  veins. 

SPINAL  SYSTEM          The  spine  is  remarkable  for  the  number  of  large 
OF  VEINS.  and  tortuous  veins  which  ramify  about  it,  inside 

and  outside  the  vertebral  canal  (fig.  193).     They  are  : — 

1.  The  dorsi-spinal  or  posterior  external  veins,  which  form  a 
tortuous  plexus  outside  the  spinous,  transverse,  and  articular  pro- 
cesses, and  the  arches  of  the  vertebrae ;  they  communicate  with 
corresponding  veins  above  and  below,  and  they  send  off  branches, 
which  pass  through  the  ligamenta  subflava  and  intervertebral 
foramina,  and  end  in  the  plexus  inside  the  vertebral  canal.  They 
join  the  vertebral  veins  in  the  cervical  region,  the  intercostal  in 
the  dorsal,  and  the  lumbar  and  sacral  veins  below. 


1.  Anterior  external 

veins. 

2.  Dorsi-spinal  veins. 


3.  Posterior    longitudinal 

spinal  veins. 

4.  Anterior  longitudinal 

spinal  veins. 


DIAGRAM   OP   THE   SPINAL   VEINS.      (VERTICAL   SECTION.) 

2.  The  veins  of  the  bodies  of  the  vertebrce  (vence  basis  verte- 
brarum),  emerge  from  the  backs  of  the  bodies,  and  empty  them- 
selves into  the  transverse  vein  connecting  the  two  anterior  longi- 
tudinal spinal  veins. 

3.  The  anterior  longitudinal  spinal  veins,  two  in  number,  one 
on  each  side,  are  very  large  tortuous  veins,  which  extend  along  the 
whole  length  of  the  spinal  canal.     They  communicate  by  trans- 
verse branches,  passing  beneath  the  posterior  common  ligament, 
opposite  the  body  of  each  vertebra,  where  they  receive  the  venae 
basis  vertebrarum.      They  are  larger  in  the   dorsal    and   lumbar 
regions,  and  communicate  externally  with  the  vertebral,  the  inter- 
costal, the  lumbar,  and  the  sacral  veins. 


782 


SPINAL   VEINS. 


4.  The  posterior  longitudinal  spinal  veins,  like  the  anterior,  run 
along  the  whole  length  of  the  spinal  canal.     They  form  a  tortuous 
venous  plexus,  situated  inside  the  vertebral  arches,  and  communi- 
cate in  front  with  the  anterior  longitudinal  veins  by  cross  branches 
at  frequent  intervals,  and  externally  with  the  vertebral,  intercostal, 
lumbar,  and  sacral  veins  by  branches  through  the  intervertebral 
foramina. 

The  anterior  and  posterior  longitudinal  spinal  veins  are  situ- 
ated between  the  spinal  canal  and  the  dura  mater  of  the  spinal 
cord,  and  are  called  the  meningo-rachidian  veins. 

5.  The  medulli-spinal  or  proper   veins  of  the  spinal  cord  lie 
within  the  dura  mater.     They  form  a  fine  plexiform  arrangement 

FIG.  194. 


1.  Anterior  external 

veins. 

2.  Dorsi-spinal  veins . 

3.  Posterior  longitudinal 

spinal  veins. 


4.  Anterior  longitudinal 

spinal  veins. 

5.  Internal  veins  of  the 

body  of  the  vertebra. 

6.  Lateral  veins. 


DIAGBAM   OF   THE    SPINAL   VEINS.       (TRANSVERSE   SECTION.) 

of  veins  over  both  surfaces  of  the  cord,  and  can  with  difficulty  be 
injected  from  the  other  spinal  veins.  This  complicated  system  of 
veins  discharges  itself  through  the  intervertebral  foramina  in  the 
several  regions  of  the  spine,  as  follows  : — In  the  cervical,  into  the 
vertebral  veins;  in  the  dorsal,  into  the  intercostal  veins;  in  the 
lumbar,  into  the  lumbar  veins.  None  are  provided  with  valves : 
hence  they  are  liable  to  become  congested  in  diseases  of  the  spine. 
The  membranes  of  the  spinal  cord,  though  the  same  in  number 
and  continuous  with  those  of  the  brain,  differ  from  them  in  certain 
respects,  and  require  separate  notice. 

D       M  The  dura  mater  of  the  cord  is  a  tough  fibrous 

membrane,  like  that  of  the  brain,  but  does  not 


MEMBRANES   OF   THE   SPINAL   CORD.  783 

adhere  to  the  bones,  being  separated  from  them  by  fat,  loose 
areolar  tissue,  and  the  plexus  of  veins  described  above.  Moreover, 
such  adhesion  would  impede  the  free  movements  of  the  vertebra 
upon  each  other.  It  is  attached  firmly  above  to  the  margin  of 
the  foramen  magnum,  and  by  slender  tissue  to  the  posterior 
common  ligament,  and  may  be  traced  downwards  as  a  sheath  as 
far  as  the  second  bone  of  the  sacrum,  from  which  it  is  prolonged  as 
a  fibrous  cord  to  the  coccyx,  where  it  becomes  continuous  with  the 
periosteum.  It  forms  a  complete  canal  or  bag  (theca)  which  sur- 
rounds loosely  the  spinal  cord,  and  is  relatively  larger  in  the  cer- 
vical and  lumbar  regions  than  in  the  dorsal.  On  each  side  are 
two  openings  in  the  dura  mater  for  the  anterior  and  posterior  roots 
of  the  spinal  nerves,  and  the  membrane  is  prolonged  over  the 
trunk  of  each  spinal  nerve.  These  prolongations  accompany  the 
nerves  only  as  far  as  the  intervertebral  foramina,  and  are  there 
blended  with  the  periosteum.  The  inner  surface  of  the  dura  mater 
is  covered  with  a  layer  of  polygonal  cells,  so  that  it  is  smooth  and 
secerning ;  this  was  formerly  described  as  the  parietal  layer  of  the 
arachnoid  membrane. 

Cut  through  the  nerves  which  proceed  from  the  spinal  cord  on 
each  side,  and  remove  the  cord  with  the  dura  mater  entire.  Then 
lay  it  flat  on  the  table  and  slit  up  the  dura  mater  along  the  middle 
of  the  front  of  the  cord  to  examine  the  arachnoid  membrane. 

It  will  be  seen  that  the  functions  of  the  dura  mater  of  the  cord 
are  not  identical  with  those  of  encephalon,  since  it  does  not  form  an 
internal  periosteum  to  the  bones  of  the  spinal  canal ;  nor  does  it 
send  in  partitions  to  support  the  cord ;  and  it  does  not  split  to  form 
venous  sinuses. 

ARACHNOID  The  arachnoid  membrane  of  the  cord  is  a  con- 

MEMBEANE.  tinuation  from  that  of  the  brain,  and  is  reflected 

over  the  spinal  nerves  as  they  pass  from  the  cord  to  the  apertures 
in  the  dura  mater.  This  membrane  invests  the  cord,  and  is  in 
contact  by  its  superficial  aspect  with  the  dura  mater,  there  being 
an  interval  between  them  called  the  siib-dural  space,  although  in 
some  situations  they  are  more  or  less  connected  by  connective- 
tissue  bands.  On  its  deeper  surface  it  is  in  contact  with  the  pia 
mater,  but  is  loosely  connected  with  it  by  delicate  areolar  tissue, 


784  MEMBKANES   OF  THE   SPINAL   CORD. 

so  that  there  is  a  considerable  interval  between  them  (siibaraclmoid 
space) ,  which  is  occupied  by  a  transparent  watery  fluid  (cerebro- 
spinal  fluid)  contained  in  the  meshes  of  the  subarachnoid  tissue. 
The  separation  between  the  arachnoid  and  the  pia  mater  varies  in 
different  parts,  and  is  greatest  in  the  lowest  part  of  the  cord. 

CEKEBBO-  This  cerebro-spinal  fluid  cannot  be  demonstrated 

SPINAL  FLUID.  unless  the  cord  be  examined  very  soon  after  death, 

and  before  the  removal  of  the  brain.1  The  nerves  proceeding  from 
the  cord  are  loosely  surrounded  by  a  sheath  of  the  arachnoid ;  but 
this  only  accompanies  them  as  far  as  the  dura  mater,  where  the 
two  are  continuous.  The  cerebro-spinal  fluid  of  the  cord  com- 
municates with  that  of  the  brain,  and  also  with  the  general  ventricu- 
lar cavity  through  an  aperture  in  the  lower  boundary  of  the  fourth 
ventricle,  called  the  foramen  of  Magendie. 

The  pia  mater  of  the  cord  is  the  protecting 
membrane  which  immediately  invests  it.  It  is 
very  different  in  structure  from  that  of  the  brain,  since  it  does  not 
constitute  a  membrane  in  which  the  arteries  break  up,  but  serves 
rather  to  support  and  strengthen  the  cord;  consequently,  it  is 
much  less  vascular,  more  fibrous  in  its  structure,  and  more  adhe- 
rent to  the  substance  of  the  cord.  It  sends  down  thin  folds  into 
the  anterior  and  posterior  median  fissures  of  the  cord,  and  is  pro- 

1  The  existence  and  situation  of  the  cerebro-spinal  fluid  were  first  discovered  by 
Haller,  Element.  Phys.  vol.  iv.  p.  87,  and  subsequently  more  minutely  investigated 
by  Magendie,  Recherches  Phys.  et  Cliniques  sur  le  Liquide  Cephalo-rachidien, 
in-4°,  avec  atlas  :  Paris,  1842.  This  physiologist  has  shown  that  if,  during  life,  the 
arches  of  the  vertebrae  are  removed  in  a  horse,  dog,  or  other  animal,  and  the  dura 
mater  of  the  cord  punctured,  there  issue  jets  of  a  fluid  which  had  previously  made 
the  sheath  tense.  The  fluid  communicates,  through  the  fourth  ventricle,  with  that 
in  the  general  ventricular  cavity.  The  collective  amount  of  the  fluid  varies  from 
1  to  2  oz.  or  more.  It  can  be  made  to  flow  from  the  brain  into  the  cord,  or  vice 
versa.  This  is  proved  by  experiments  on  animals,  and  by  that  pathological  condi- 
tion of  the  spine  in  children  termed  spina  bifida.  In  the  later  instance,  coughing 
and  crying  make  the  tumour  swell ;  showing  that  fluid  is  forced  into  it  from  the 
ventricles.  Again,  if  pressure  be  made  on  the  tumour  with  one  hand  and  the 
fontanelles  of  the  child  examined  with  the  other,  in  proportion  as  the  spinal 
swelling  decreases  so  is  the  brain  felt  to  swell  up,  accompanied  by  symptoms 
resulting  from  pressure  on  the  nervous  axis  generally.  See  some  remarks  very 
much  to  the  point  by  Sir  George  Burrows,  On  Diseases  of  the  Cerebral  Circulation, 
p.  50,  1846. 


LIGAMENTDM   DENTICULATUM. 


785 


longed  upon  the  spinal  nerves,  forming  their  investing  membrane 
or  '  neurilemma.' 

Along  the  anterior  median  fissure  may  be  traced  a  well-marked 
fibrous  band,  formed  by  the  pia  mater,  which  has  been  named  the 
linea  splendens. 

Below  the  level  of  the  second  lumbar  vertebra,  the  pia  mater 
is  continued  as  a  slender  filament,  called  the  filum  terminate,  or 
central  ligament,  which  runs  down  in  the  middle  of  the  bundle  of 
nerves  into  which  the  spinal  cord  breaks  up.  About  the  level  of 
the  third  sacral  vertebra  it  becomes  continuous  with  the  dura  mater 
of  the  cord,  and  is  then  prolonged  as  far  as  the  base  of  the  coccyx. 
The  spine  of  the  third  sacral  vertebra  marks  the  level  to  which  the 
cerebro-spinal  fluid  descends  in  the  vertebral  canal.  It  is  supplied 
with  nerves  from  the  sympathetic  and  from  the  posterior  roots  of 
the  spinal  nerves. 

LIGAMENTUM  From  each  side   of  the  FlG-  !95- 

DENTICULATUM.  cord  along  its  whole  length 
there  runs  a  fibrous  band,  ligamentum  den- 
ticulatum,  which  gives  off  a  series  of  pro- 
cesses to  steady  and  support  the  cord.  They 
are  triangular,  their  bases  being  attached  to 
the  cord,  and  their  points  to  the  inside  of 
the  dura  mater  (fig.  195).  There  are  from 
eighteen  to  twenty-two  of  them  0^1  each  side, 
and  they  lie  between  the  anterior  and  pos-  DIAGRAM  OF  THE  LIGA- 
terior  roots  of  the  spinal  nerves.  The  first  MENTUM  DENTICULATUM. 
process  passes  between  the  vertebral  artery  i><P"r!.mater\ 

J     2,  2, 2.  Ligamentum  denticuiatunu. 

and  the  hypoglossal  nerve ;  the  last  is  found 

at  the  termination  of  the  cord.     It  is  composed  of  fibrous  tissue, 

and  is  covered  with  nucleated  cells  continuous  with  the  arachnoid 

membrane.1 

1  Vide  Axel  Key  and  Eetzius ;  Max  Schultze's  Archives,  1873. 


3E 


786  THE   SPINAL   CORD. 


SPINAL   CORD. 

The  spinal  cord  (medulla  spinalis)  is  that  part  of  the  cerebro- 
spinal  axis  contained  in  the  vertebral  canal,  and  is  enclosed  within 
a  sheath  of  dura  mater  (theca  vertelralis),  which  is  separated  from 
the  canal  by  a  plexus  of  veins  and  connective  tissue.  It  is  the  con- 
tinuation of  the  medulla  oblongata,  and  extends  from  the  foramen 
magnum  down  to  the  lower  border  of  the  first  lumbar  vertebra, 
where  it  terminates  in  a  conical  point,  conus  medullaris,  after  having 
given  off  a  large  bundle  of  nerves,  termed  the  cauda  equina,  for  the 
supply  of  the  lower  limbs. 

It  is  from  fifteen  to  eighteen  inches  in  length,  and  is  about  an 
ounce  and  a  half  in  weight.  Its  lower  extremity  from  the  conus 
medullaris  is  continued  downwards  as  thin  silvery  cord,  the  filum 
terminate,  which  descends  along  the  posterior  aspect  of  the  cauda 
equina.  It  passes  down  within  the  sheath  as  far  as  the  second 
sacral  vertebra,  and  then,  piercing  the  dura  mater,  becomes  attached 
to  the  periosteum  of  the  canal  at  the  back  of  the  coccyx.1  In  its 
upper  part,  the  filum  terminale  contains  some  grey  nerve-substance. 
It  is  a  prolongation  of  the  pia  mater  of  the  cord,  and  in  many 
subjects  there  is  a  continuation  of,  the  central  canal  of  the  cord  in 
its  upper  half. 

The  cord  is  not  of  uniform  dimensions  throughout.  It  presents 
a  considerable  enlargement  in  the  lower  part  of  the  cervical  region ; 
another  in  the  lower  part  of  the  dorsal,  from  which  proceed  the 
large  nerves  to  the  upper  and  lower  limbs,  respectively.  The  upper 
or  cervical  enlargement,  which  is  the  larger,  extends  from  the 
third  cervical  to  the  first  dorsal  vertebra,  and  is  largest  at  the 
sixth  cervical  vertebra ;  the  lower,  or  lumbar,  extends  from  the 

1  The  explanation  of  this  is,  that,  at  an  early  period  of  foetal  life,  the  length  of 
the  cord  corresponds  with  that  of  the  vertebral  canal ;  but  after  the  third  month, 
the  lumbar  and  sacral  vertebras  grow  away  from  the  cord,  in  accordance  with  the 
more  active  development  of  the  lower  limbs.  See  Tiedemann,  Anatomie  und 
Bildungsgeschichte  des  Gehirns  im  Fcettis  des  Menschen,  &c. ;  Nuremberg,  1816. 


THE   SPINAL   CORD.  787 

twelfth  dorsal   vertebra,    and   is   largest  opposite  the  last  dorsal 
vertebra.1 

The  cord  is  divided  into  two  symmetrical  halves  by  a  median 
longitudinal  fissure  in  front  and  behind  (fig.  196).  The  anterior 
iissure  is  the  more  distinct  and  wider,  and  penetrates  about  one- 
third  of  the  substance  of  the  cord ;  deeper  in  the  lower  than  in  the 
upper  part  of  the  cord.  It  contains  a  fold  of  pia  mater,  with  many 
blood-vessels  for  the  supply  of  its  interior.  At  the  bottom  of  this 
fissure  is  a  transverse  layer  of  white  substance,  named  the  anterior 
white  commissure,  connecting  the  two  anterior  halves  of  the  cord. 
The  posterior  fissure  is  much  less  apparent  than  the  anterior,  and  is 
better  marked  in  the  upper  and  the  lower  parts  of  the  cord.  It 
does  not  contain  a  fold  of  pia  mater,  but  contains  a  thin  septum  of 

FIG.  196. 


DIAGRAM    OF    A    TRANSVERSE    SECTION    THROUGH    THE    SPINAL    CORD 
AND    ITS    MEMBRANES. 

1.  Dura  mater.  4.  Anterior  root  of  spinal  nerve. 

2.  Arachnoid  membrane.  5,  5.  Seat  of  sub-arachnoid  fluid. 

3.  Ganglion  on  posterior  root  of  6.  Posterior  branch  of  spinal  nerve. 

spinal  nerve.  7.  Anterior  branch  of  spinal  nerve. 


connective  tissue  with  blood-vessels.  It  can  be  traced  to  a  greater 
depth  than  the  anterior,  and  reaches  down  as  far  as  the  posterior 
grey  commissure  of  the  cord. 

Besides  the  anterior  and  posterior  fissures,  is  another  superficial 
lateral  groove,  from  which  the  posterior  roots  of  the  spinal  nerves 
emerge  ;  this  is  termed  the  postero-lateral  groove  (fig.  196).  This 
leads  down  to  the  posterior  horn  of  the  grey  matter  in  the  interior 

1  In  very  early  foetal  life  these  enlargements  do  not  exist,  and  only  make  their 
appearance  with  the  development  of  the  extremities. 

3  E  2 


788  THE   SPINAL   CORD. 

of  the  cord.  There  is  sometimes  described  an  antero-lateral  groove, 
corresponding  to  the  line  whence  the  anterior  roots  of  the  spinal 
nerves  emerge ;  but  this  is  not  really  a  groove,  although  it  serves 
to  map  out  each  half  of  the  cord  into  three  longitudinal  portions  : 
a  posterior,  a  lateral,  and  an  anterior  column.  On  each  side  of  the 
posterior  median  fissure,  in  the  cervical  region,  is  a  slender  column, 
called  the  posterior  median  column,  which  is  separated  from  the  pos- 
terior column  by  a  shallow  furrow.1  The  anterior  column  is  continu- 
ous with  the  anterior  pyramid  ;  the  lateral  column  with  the  lateral 
tract  of  the  medulla  ;  the  posterior  column  with  the  restiform  body ; 
and  the  posterior  median  column  with  the  posterior  pyramid. 

INTERNAL  A  transverse  section  through  the  cord  (fig.  196) 

STKUCTUKE.  shows   that,  externally,  it  is  composed  of  white 

nerve-substance,  and  that  its  interior  contains  grey  matter,  arranged 
in  the  form  of  two  crescents,  with  their  backs  to  each  other.  Each 
crescent  is  placed  in  its  corresponding  half  of  the  cord,  and  is  con- 
nected with  its  fellow  across  the  centre  by  a  portion  called  the  pos- 
terior or  grey  commissure.  The  posterior  horns  are  long  and  narrow, 
and  extend  to  the  postero-lateral  groove,  where  they  are  connected 
with  the  posterior  roots  of  the  spinal  nerves.  At  their  extremities 
they  taper  to  a  point,  the  apex  cornu  posterioris,  and  near  their  bases 
they  present  a  constriction,  the  cervix  cornu,  beyond  which  they 
slightly  enlarge  to  form  the  caput  cornu.  The  outline  of  the  grey 
matter  of  the  posterior  horns  at  their  commencement  is  indefinite 
and  frayed  out,  which  is  especially  noticeable  in  the  cervical  region, 
and  is  called  the  processus  reticularis  ;  at  their  apices  the  grey 
matter  is  semitransparent  in  appearance,  and  hence  is  known  as  the 
siibstantia  gelatinosa.  In  the  centre  of  the  concavity  of  the  posterior 
horn  is  a  rounded  projection,  most  marked  in  the  upper  dorsal 
region,  termed  the  tractus  intermedio-lateralis,  the  continuation  of 
which  has  been  traced  upwards  through  the  medulla  oblongata.  The 
anterior  horns  are  short  and  thick,  and  come  forwards  towards  the 
attachment  of  the  anterior  roots  of  the  nerves,  but  do  not  reach  the 
surface.  Separating  the  grey  commissure  from  the  anterior  median 
fissure  is  the  anterior  or  white  commissure. 

1  The  posterior  median  column  is  said  by  Foville  to  be  present  along  the  whole 
length  of  the  cord. 


THE   SPINAL    CORD.  789 

On  making  transverse  sections  through  different  regions  of  the 
spinal  cord,  the  grey  substance  is  seen  to  vary  in  shape  and  in 
amount :  in  the  cervical  region,  the  anterior  cornua  are  thick  and 
short,  the  posterior  are  long  and  slender ;  in  the  dorsal,  the  anterior 
and  posterior  cornua  are  both  thin ;  in  the  lumbar,  the  anterior  and 
posterior  cornua  are  large  and  broad ;  in  the  lower  part  of  the  cord 
the  grey  matter  is  arranged  in  a  central  mass. 

Running  along  the  centre  of  the  cord  in  its  whole  length  is  a 
minute  canal,  the  central  canal,  just  visible  to  the  naked  eye. 
Below,  in  the  conus  medullaris,  it  ends  in  a  dilated  cul-de-sac,  of 
the  shape  of  the  letter  T ;  above,  it  opens  out  at  the  calamus  scrip- 
torius  into  the  fourth  ventricle.  It  is  lined  with  cylindrical  ciliated 
epithelium.  This  central  canal  is  interesting,  as  it  is  the  remains 
of  the  cavity  formed  by  the  spinal  cord  at  the  earliest  period  of  its 
development.1 

Thirty-one  pairs  of  nerves  arise  from  the  spinal 
cord,  namely  eight  in  the  cervical  region,  twelve  in 
the  dorsal,  five  in  the  lumbar,  five  in  the  sacral,  and  one  in  the 
coccygeal.  Each  nerve  is  formed  by  the  junction  of  two  series  of 
roots,  one  from  the  front,  which  is  the  motor  root,  the  other  from  the 
back  of  the  cord,  which  is  the  sensory  and  larger  root.  The  two 
roots  pierce  the  dura  mater  separately  and  then  converge  to  the 
corresponding  intervertebral  foramen  to  form  a  single  nerve,  com- 
posed of  motor  and  sensory  filaments. 

The  filaments  composing  the  posterior  roots  are  finer,  but  their 
fasciculi  are  thicker  and  more  numerous  than  the  anterior.2  They 
proceed  from  the  postero-lateral  fissure,  and  previous  to  their  union 
with  the  anterior  roots  are  collected  into  two  bundles  which  pass 
through  a  ganglion.  The  ganglion  is  of  an  oval  form,  bilobate  on 
its  external  extremity,  and  lies  in  the  intervertebral  foramen;  each 
fasciculus  of  the  posterior  root  enters  the  corresponding  lobe  of  the 
ganglion.  The  ganglia  of  the  first  and  second  cervical  nerves  are 
placed  upon  the  arches  of  the  atlas  and  axis  respectively;  the 
ganglia  of  the  sacral  and  coccygeal  nerves  are  situated  within 

The  central  canal  is  well  seen  in  fishes,  birds,  and  reptiles. 
*  This  does  not  apply  to  the  first  cervical  nerve,  in  which  the  anterior  root 
exceeds  the  posterior  in  size. 


790  THE   SPINAL   CORD. 

the  spinal  canal.  The  anterior  roots  arise  from  the  antero-lateral 
column,  are  smaller  than  the  posterior  roots,  but  like  them  divide 
into  two  fasciculi  as  they  approach  the  ganglion  on  the  posterior 
root.1 

The  compound  nerve  formed  by  the  junction  of  the  two  roots, 
external  to  the  ganglion  of  the  posterior,  divides,  outside  the  inter- 
vertebral  foramen,  into  an  anterior  and  a  posterior  (dorsal)  branch. 
(See  diagram,  p.  787.) 

The  fibres  of  the  anterior  roots,  after  entering  the  antero-lateral 
column,  pass  through  the  white  fibres  to  enter  the  grey  matter ; 
here  they  pass  in  all  directions,  the  larger  number  passing  upwards 
and  downwards,  and  some  decussating  with  corresponding  filaments 
of  the  opposite  side,  through  the  anterior  white  commissure  ;  some 
also  pass  upward  vertically  through  the  lateral  column.  The  fibres 
of  the  posterior  roots  enter  the  caput  cornu  posterioris  through  the 
postero-lateral  groove,  and  then  pass  upwards  and  downwards  in 
the  grey  matter,  chiefly  of  the  posterior  horn,  but  some  curve  round 
to  enter  the  anterior  horn,  while  others  pass  to  the  opposite  side 
through  the  posterior  grey,  commissure. 

VARIATION  IN  ^he  direction  and  length  of  the  roots  of  th-> 

THE  LENGTH  OF  nerves  vary  in  the  different  regions  of  the  spine, 
THE  BOOTS.  owing  to  the  respective  parts  of  the  cord  from 

which  they  arise  not  being  opposite  to  the  foramina  through  which 
the  nerves  leave  the  spinal  canal.  In  the  upper  part  of  the  cer- 
vical region,  the  origins  of  the  nerves  and  their  point  of  exit  are 
nearly  on  the  same  level ;  therefore  the  roots  proceed  transversely, 
and  are  very  short.  Lower  down,  however,  the  obliquity  and 
length  of  the  roots  gradually  increase,  so  that  the  roots  of  the 
lower  dorsal  nerves  are  at  least  a  vertebra  higher  than  the  fora- 

1  The  researches  of  Blandin,  Anat.  descript.,  t.  ii.,  p.  648, 1838,  have  led  him  to 
establish  the  following  relation  between  the  respective  size  of  the  anterior  and 
posterior  roots  of  the  nerves  in  the  several  regions  of  the  spine  : — 

The  posterior  roots  are  to  the  anterior  in  the  cervical  region         : :     2     :     1 
»  u  „  dorsal        ,,  ::     1     :     1 

>»  »  ,,  lumbar  and  sacral  : :     1£  :     1 

This  relation  quite  accords  with  the  greater  delicacy  of  the  sense  of  touch  in 
the  upper  extremity. 


THE   SPINAL   CORD.  791 

mina  through  which  they  emerge.  Again,  since  the  cord  itself 
terminates  at  the  lower  border  of  the  first  lumbar  vertebra, 
the  lumbar  and  sacral  nerves  must  descend  from  it  almost  per- 
pendicularly through  the  lower  part  of  the  spinal  canal.  To 

this  bundle   of  nerves  the  old   anatomists  have 

CADDAEQUINA.  _  . 

given  the  name  01  cauda  equina,  irom  its  resem- 
blance to  a  horse's  tail. 

To  sum  up  briefly,  it  appears  that  the  spinal  cord  consists  of 
two  symmetrical  halves,  separated  in  front  and  behind  by  a  deep 
median  fissure ;  that  the  two  halves  are  connected  at  the  bottom 
of  the  anterior  fissure  by  an  anterior  or  white  commissure,  at  the 
bottom  of  the  posterior  fissure  by  the  posterior  or  grey  commissure  ; 
that  each  half  of  the  cord  is  divided  into  three  tracts  or  columns 
of  longitudinal  white  nerve-fibres — an  anterior,  a  lateral,  and  a 
posterior — the  boundaries  between  them  being  the  respective  lines 
of  origin  of  the  roots  of  the  spinal  nerves ;  that  the  interior  of  the 
cord  contains  grey  matter  disposed  in  the  form  of  two  crescents, 
placed  with  their  convexities  towards  each  other,  and  connected 
by  a  transverse  bar  of  grey  matter,  which  constitutes  the  posterior 
commissure. 

BLOOD-VESSELS          The  cord  is  supplied  with  blood  by — 1.  The 
OF  THE  COED.  anterior  spinal  artery,  which  commences  at  the 

medulla  oblongata  by  a  branch  from  the  vertebral  of  each  side, 
and  then  runs  down  the  middle  of  the  front  of  the  cord.  Other 
branches  are  derived  from  the  vertebral,  ascending  cervical,  inter- 
costal, and  lumbar  arteries,  which  pass  through  the  intervertebral 
foramina,  and  assist  in  keeping  up  the  size  of  this  anterior  artery. 
2.  The  posterior  spinal  arteries,  which  proceed  also  from  the 
vertebral,  intercostal,  and  lumbar  arteries,  and  ramify  somewhat 
irregularly  on  the  back  of  the  cord. 

On  the  posterior  part  of  the  bodies  of  the  vertebra3,  the  spinal 
arteries  of  opposite  sides  communicate  by  numerous  transverse 
branches  along  the  entire  length  of  the  spine,  thus  resembling 
the  arrangement  of  its  venous  plexuses. 

FUNCTIONS  OF  The  spinal  cord  performs,  at  least,  three  func- 

THE  SPINAL  COED,  tions  : — 1.  It  is  the  general  conductor  of  impres- 
sions to,  and  from,  the  brain.  2.  It  transfers  impressions.  3.  It 


792  THE   SPINAL   CORD. 

is  a  centre  of  reflex  action.  Sensory  impressions  are  conducted  by 
the  posterior  roots  of  the  spinal  nerves  to  the  cord,  and  are  thence 
transmitted  to  the  brain  through  the  posterior  columns  and  the 
grey  matter  of  the  cord.  These  impressions  do  not  run  up  on  the 
same  side,  for  the  fibres,  immediately  on  entering  the  grey  matter, 
cross  over  to  the  opposite  side  to  reach  the  brain ;  so  that  if  the 
posterior  column  of  the  right  side  be  divided,  the  left  leg,  and  not 
the  right,  would  be  deprived  of  sensation.  Motor  impulses  are 
conveyed  along  the  antero-lateral  columns  and  the  grey  matter  in 
them,  and  carry  the  commands  of  the  will  from  the  brain  to  the 
muscles.  The  crossing  of  the  motor  fibres  takes  place  in  the 
medulla  oblongata,  at  the  decussation  of  the  anterior  pyramids,  so 
that  they  run  in  the  corresponding  half  of  the  cord  as  far  as  their 
point  of  decussation.  Division,  therefore,  of  one  half  of  the  cord 
below  this  point,  causes  paralysis  of  motion  on  the  same  side  of 
the  body.  The  cord  is,  moreover,  concerned  in  the  conduction 
of  impressions  to  and  from  the  vaso- motor  centre  of  the  medulla 
oblongata,  which  determines  the  varying  conditions  of  the  blood- 
vessels. The  cord  also  transfers  impressions :  this  is  more  manifest 
in  disease  than  in  health  ;  a  well-marked  example  of  transference  is, 
that  pain  is  felt  at  the  knee  in  cases  of  disease  of  the  hip-joint. 
The  spinal  cord  has  probably  no  power  of  originating  impressions, 
in  other  words,  it  is  not  automatic. 


793 


DISSECTION  OF  THE  EYE. 

SINCE  the  eye  in  the  human  subject  cannot  be  obtained  suffi- 
ciently fresh  for  anatomical  purposes,  the  student  should  examine 
the  eye  of  the  sheep,  bullock,  or  pig.  The  conjunctiva  should  be 
removed,  together  with  the  loose  connective  tissue  which  unites  it 
to  the  sclerotic  coat. 

The  conjunctiva  is  the  mucous  membrane  which 

covers  the  ocular  surface  of  the  eyelids  and  the 

anterior  part  of  the  globe.     It  presents  different  characters  in  the 

various  situations  over  which  it  is  reflected,  and  is  described  as  the 

palpebral,  the  sclerotic,  and  the  corneal  portions. 

The  palpebral  portion  is  thicker  than  the  other  portions,  is  very 
vascular,  and  is  provided  with  fine  papillae  abundantly  supplied 
with  nerves.1  As  described  p.  30,  it  is  continuous  with  the  mucous 
membrane  of  the  lachrymal  sac  through  the  canaliculi,  and  lines 
the  Meibomian  glands  and  the  ducts  of  the  lachrymal  gland.  The 
columnar  epithelium  which  lines  the  palpebral  conjunctiva  be- 
comes at  the  margins  of  the  eyelids  more  stratified  and  continuous 
with  the  flattened  cells  of  the  skin  of  the  eyelid.  It  forms  at  the 
inner  canthus  a  reduplicated  fold,  the  plica  semihinaris,  and  is 
reflected  from  the  eyelids  to  the  globe,  its  angle  of  reflection  being 
called  the  fornix  conjunctives,  and  the  folds  into  which  this  is 
thrown  are  termed  the  superior  and  inferior  palpebral  folds. 

The  sclerotic  conjunctiva  is  loosely  attached  by  submucous  tissue 
to  the  sclerotic  coat,  so  as  not  to  impede  the  movements  of  the  globe. 
It  is  thinner,  and  has  no  papillas.  It  is  transparent  and  nearly 
colourless,  except  when  inflamed ;  it  then  becomes  intensely  vascu- 
lar, and  of  a  bright  scarlet  colour.  The  arteries  are  derived  from 

1  These  papilla  were  first  described  by  Eble,  Ueber  den  Bau  und  die  Krarik- 
heitf.n  der  Bindehaut  des  Auges. 


794  CONJUNCTIVA. 

the  lachrymal  and  palpebral  branches  of  the  ophthalmic  artery  r 
and  at  the  circumference  of  the  cornea  they  form  capillary  loops 
which  anastomose  with  each  other.  The  lymphatics  are  well 
marked  in  the  palpebral  and  sclerotic  portions  of  the  conjunctiva, 
and  aj  the  margin  of  the  cornea  they  rapidly  diminish  in  size 
and  become  connected  with  the  cell-spaces  in  the  cornea.  An 
abundant  supply  of  nerves  is  distributed  to  the  membrane ;  their 
arrangement  is  in  the  form  of  plexuses  as  far  as  the  margin  of 
the  cornea,  where  they  terminate  in  '  end-bulbs,'  described  by 
Krause,  resembling  in  many  respects  the  central  portion  of  Pacinian 
corpuscles. 

The  corneal  conjunctiva  is  composed  chiefly  of  epithelium  ar- 
ranged in  layers,  the  deepest  of  which  consists  of  columnar  cells 
resting  by  their  bases  on  the  substantia  propria  of  the  cornea; 
superficial  to  these  are  two  or  three  layers  of  polygonal  cells,  the 
deepest  of  which,  called  the  fingered  cells  of  Cleland,  interdigitate 
with  the  columnar  cells  ;  and  on  the  surface  there  is  a  layer  of 
flattened  squamous  epithelial  cells.  This  portion  of  the  conjunctiva 
cannot  be  separated  by  dissection  in  recent  eyes,  but  it  possesses 
the  same  acute  sensibility  as  the  rest  of  the  conjunctiva.  Changes 
produced  by  inflammation  of  the  conjunctiva  often  involve  the 
cornea  and  render  its  texture  thick  and  opaque.1 

The  eyeball  is  embedded  in  a  large  quantity  of  fat  and  delicate 
connective  tissue  ;  and  surrounding  it  in  its  posterior  three-fourths 
is  a  serous  membrane,  the  capsule  of  Tenon,  which  allows  of  its 
free  movement  in  the  orbit. 

The  axes  of  the  two  eyeballs  are  nearly  parallel  with  each 
other ;  thus  they  do  not  correspond  with  the  axes  of  the  orbits, 
nor  of  the  optic  nerves  which  enter  the  globes  on  their  nasal 
aspect. 

The  human  eye  is  nearly  spherical,  and  consists  of  segments  of 
two  spheres:  a  large  posterior  one,  which  corresponds  with  the 

1  The  facts  of  comparative  anatomy  confirm  this  view.  In  the  serpent  tribe, 
which  annually  shed  the  skin,  the  front  of  the  cornea  comes  off  with  the  rest  of 
the  external  surface  of  the  body.  In  the  eel  the  surface  of  the  cornea  is  often 
drawn  off  in  the  process  of  skinning.  In  some  species  of  rodents  which  burrow 
under  the  ground  like  the  mole,  the  eye  is  covered  with  hair,  like  other  parts. 


SCLEROTIC   COAT.  795 

sclerotic,  and  a  small  anterior  one  with  the  cornea.  The  antero- 
posterior  and  vertical  diameters  of  the  globe  are  equal,  the  trans- 
verse exceeding  these  by  less  than  half  a  line.  The  convexity  of 
the  cornea  varies  in  different  persons  and  at  different  periods  of 
life  ;  this  is  one  cause  of  the  varying  degrees  of  near  and  far  sight. 
COATS  AND  The  globe  is  composed  of  three  concentric  coats, 

HUMOURS  OF  arranged  one  within  the  other,  which  enclose  cer- 

THE  EYE.  tain  transparent  structures  for  the  transmission  of 

light.  The  external  coat,  consisting  of  the  sclerotic  and  cornea, 
is  fibrous,  thick,  and  strong.  The  second  coat,  consisting  of  the 
clioroid,  the  iris,  and  the  ciliary  processes,  is  composed  of  blood- 
vessels, muscular  tissue,  and  pigment  cells,  and  is  very  dark  in 
colour.  The  third  coat,  called  the  retina,  consists  of  the  expansion 
of  the  optic  nerve  for  the  reception  of  the  impression  of  the  waves 
of  light.  The  bulk  of  the  interior  is  filled  with  a  transparent 
humour,  called  the  vitreous  body.  Embedded  in  the  front  of  this, 
and  just  behind  the  pupil,  is  the  crystalline  lens,  for  the  purpose 
of  concentrating  the  rays  of  light.  In  front  of  the  lens  is  placed  a 
moveable  curtain,  called  the  iris,  to  regulate  the  amount  of  light 
which  shall  be  admitted  through  a  central  aperture,  the  pupil,  to 
the  fundus  of  the  eye.  The  space  in  which  the  iris  is  suspended 
is  filled  with  a  fluid,  termed  the  aqueous  humour. 

The  sclerotic  coat  is  the  white  tough  protecting 
SCLEROTIC  COAT.  „     ,  ,  .  ,  .  °  -. A  _ 

coat  ot  the  eye  which  serves  to  maintain  the  form 

of  the  globe.1  It  covers  the  posterior  five-sixths  of  the  globe,  the 
remaining  anterior  one-sixth  being  completed  by  the  cornea.  It 
is  of  dense  white  colour,  except  in  front,  where  the  tendons  of  the 
recti  and  obliqui  are  inserted  into  it.  The  thickest  part  of  the 
sclerotic  coat  is  at  the  back  of  the  globe  (fig.  198)  ;  the  thinnest 
is  a  short  distance  behind  the  cornea.2  The  back  of  the  sclerotic 
is  perforated  by  the  optic  nerve,  which  enters  it  about  one-tenth 

1  The  sclerotic  coat  of  the  eye  in  fishes  is  of  extraordinary  thickness  and 
density ;  and  in  birds  this  coat  is  further  strengthened  by  a  circle  of  bony  plates, 
fourteen  or  fifteen  in  number,  arranged  in  a  series  round  the  margin  of  the  cornea. 
Similar  plates  are  found  in  some  of  the  reptiles,  and  particularly  in  the  fossil 
ichthyosauri  and  plesiosauri. 

2  The  greatest  thickness  posteriorly  is  about  the  ^th  of  an  inch  ;  its  thinnest 
in  front  is  about  the  ^th  of  an  inch. 


796 


SCLEEOTIC   COAT. 


FIG.  197. 


of  an  inch  on  the  inner  or  nasal  side  of  the  axis  of  vision.  The 
sheath  of  the  optic  nerve  becomes  continuous  with  the  sclerotic, 
where  it  perforates  this  coat.  The  optic  nerve  at  its  entrance  into 
the  sclerotic  is  much  constricted,  and  instead  of  passing  through  a 
single  aperture  in  this  coat,  it  enters  it  through  a  number  of  minute 
apertures,  so  that  this  membrane  forms  a  porous  lamina,  called  the 
lamina  cribrosa.  In  the  centre  of  the  lamina  cribrosa  is  an  opening 
(porus  opticiis),  larger  than  the  rest,  which  transmits  the  arteria 
centralis  retinas.  Around  the  optic  nerve  the  sclerotic  is  pierced  by 
the  ciliary  arteries,  veins,  and  nerves,  for  the  supply  of  the  choroid 
and  iris.  About  a  quarter  of  an  inch  from  the  cornea  the  sclerotic 

receives  the  insertions  of  the  recti 
muscles ;  here  also  it  transmits  the 
anterior  ciliary  arteries,  which  run 
forward  along  the  tendons  of  these 
muscles,  and  form  a  vascular  ring 
around  the  circumference  of  the 
cornea  (fig.  197). 

The    sclerotic    is 
STRUCTUKE.  _        ., 

composed  ot  con- 
nective tissue  arranged  in  bundles, 
which  run,  some  longitudinally, 
some  transversely,  and  are  inter- 
mingled with  fine  elastic  fibres. 
The  longitudinal  fibres  are  the  most 
external  and  abundant.  Under  the 

microscope  numerous  connective-tissue  corpuscles  may  be  seen 
filling  cell-spaces,  similar  to  those  in  the  cornea  but  not  so 
a,bundant,  and  containing  pigment-granules.  The  inner  surface  of 
the  sclerotic  is  of  a  dark  brownish  colour,  due  to  the  presence  of  a 
thin  layer  of  connective  tissue,  lamina  fusca,  in  which  are  found 
pigment-cells.  This  surface  of  the  sclerotic  is  grooved  for  the  pas- 
sage of  the  ciliary  nerves,  which  run  forward  ifl  a  sort  of  lymph- 
space  ;  and  it  is,  moreover,  connected  by  filamentous  tissue  with 
the  subjacent  choroid  coat. 

The  cornea  is  the  brilliant  translucent  coat  which 
forms  about  the  anterior  one-sixth  of  the  globe.    It 


INSERTION  OF  THE  RECTI  MUSCLES  WITH 
ANTERIOR    CILIARY    ARTERIES. 


CORNEA. 


THE   CORNEA. 


797 


is  nearly  circular  in  shape,  its  diameter  being  nearly  half  an  inch, 
and  its  thickness  about  -^kh.  of  an  inch.  The  curve  of  the  cornea 
forms  part  of  a  smaller  circle  than  that  of  the  sclerotic,  so  that  it 
projects  further  forwards,  varying  in  this  respect  in  different  eyes, 
and  at  different  ages  of  life.  It  is  firmly  connected  at  its  margin 
to  the  sclerotic,  with  the  fibres  of  which  it  is  continuous.  The 
margin  of  the  sclerotic  is  bevelled  on  the  inside  ;  that  of  the  cornea 
on  the  outside,  so  that  the  former  overlaps  the  latter  (fig.  198). 
To  examine  the  cornea,  it  should  be  removed  with  the  sclerotic 

Fia.  198. 


Hyaloid  membrane      — 


Retina  (dotted  line) 

Choroid  coat  (black 

line) 

Sclerotic  coat     .    . 


Cornea. 

Iris. 

Ciliary  processes . 

CanalofSchlemm 

or  Fontana. 
Ciliary  muscle. 


DIAGRAM   OF   A  VERTICAL   SECTION   OF   THE    EYE. 

1.  Anterior  chamber  filled  with  aqueous  humour. 

2.  Posterior  chamber.  3.  Canal  of  Petit. 

coat.  This  should  be  done  under  water,  by  making  a  circular  cut 
with  scissors,  about  a  quarter  of  an  inch  from  the  margin  of  the 
cornea.  With  a  little  care  it  will  be  easy  to  remove  the  outer  coat 
of  the  eye  without  injuring  the  dark  choroid  coat,  the  ciliary 
muscle,  or  the  iris.  In  the  loose  brown-coloured  connective  tissue 
between  the  sclerotic  and  the  choroid  are  the  ciliary  nerves  passing 
forwards  to  the  iris  ;  their  white  colour  makes  them  very  con- 
spicuous on  the  dark  ground. 

The  cornea  consists  of  four  layers,  which  are 
not  all  composed  of  the  same  kind  of  tissue ;  they 


STRUCTURE. 


798  STRUCTURE  OF  THE  CORNEA. 

are,  from  without  inwards,  the  conjunctiva,  the  substantia  propria  or 
cornea  proper,  the  posterior  elastic  lamina,  and  the  epithelial  lining. 

The  conjunctiva  is  the  most  superficial  layer,  and  consists  of 
several  strata  of  epithelial  cells ;  the  deeper  ones  are  columnar  and 
placed  vertically,  the  next  consist  of  several  layers  of  polygonal 
cells,  and  the  most  superficial  ones  are  flattened  scaly  epithelium 
cells,  with  well-marked  nuclei. 

The  cornea  proper  or  substantia  propria  consists  of  translucent 
connective  tissue,  upon  which  the  thickness  and  strength  of  the 
cornea  mainly  depend.  The  fibres  are  arranged  in  laminae,  about 
sixty  in  number.  Those  composing  a  lamina  are  arranged  in  a 
parallel  direction,  but  the  fibres  of  each  layer  cross  at  right  angles 
those  of  each  succeeding  layer.  The  lamellae  are  connected  to- 
gether by  filaments  passing  from  one  to  another,  so  that  they  are 
not  perfectly  separate  from  each  other.  The  cornea  proper  in  the 
recent  subject  presents  no  trace  of  structure,  but  it  is  only  after  death 
by  means  of  lenses  and  reagents  that  these  lamellaa  can  be  satisfac- 
torily demonstrated.  Between  the  lamellae  are  irregularly  branched 
spaces,  called  the  cell-spaces  of  the  cornea,  in  which  are  lodged  the 
corneal  corpuscles,  having  outstanding  processes,  which  communicate 
freely  with  each  other  in  their  own  plane,  and  also  with  those 
of  the  planes  on  either  side.  These  corpuscles  correspond  in 
shape  to  the  spaces  within  which  they  lie.1  In  inflammation  of 
the  cornea  they  undergo  considerable  changes.  Immediately  below 
the  conjunctiva,  the  cornea  proper  presents  a  different  appearance 
to  that  of  the  main  thickness  of  this  layer,  so  that  this  has  been 
described  by  some  anatomists  under  the  name  of  the  anterior  elastic 
lamina  of  Bowman.  It  presents,  however,  a  definite  fibrillar  struc- 
ture, similar  to  that  of  the  cornea  proper,  but  is  destitute  of  the 
corneal  corpuscles  and  cells.  The  greatest  thickness  of  the  cornea 
proper  is  about  -^g-th  of  an  inch,  and  that  of  the  anterior  elastic 
lamina  about  j-gViyth  °f  an  inch. 

1  If  fluid  be  injected  very  gently  into  the  cornea  proper,  there  may  be  demon- 
strated a  system  of  canals,  called  Rccklingliauseri' s  canals,  which  are  the  commu- 
nications between  the  corneal  corpuscles  ;  but  if  the  fluid  be  injected  more  forcibly, 
it  passes  in  the  course  of  the  fibres  composing  the  various  lamins  of  the  cornea, 
which  gives  the  appearance  of  a  number  of  varicose  and  enlarged  tubes  crossing 
each  other  at  right  angles  :  these  are  termed  'Bowman's  corneal  tubes. 


STRUCTURE  OF  THE  CORNEA.  799 

The  posterior  elastic  lamina,  called  also  the  membrane  of  Desce- 
met  or  Demours,  is  translucent,  elastic,  and  brittle,  and  may  be 
easily  separated  from  the  preceding  lamina.  It  consists  of  a  per- 
fectly structureless  lamina,  which,  when  peeled  off,  has  a  remark- 
able tendency  to  curl  with  the  attached  surface  innermost.  It  is 
unaffected  by  boiling,  or  by  the  action  of  acids  or  alkalies,  and  is 
from  ^-^L-Q-th  to  -^-J^-th  of  an  inch  in  thickness.  At  the  junction 
of  this  lamina  with  the  sclerotic  on  its  inner  surface,  it  spreads  out 
into  a  number  of  radiating  tooth-like  processes,  the  ligamentum 
pectinatum  iridis,  which  are  attached  to  the  front  of  the  circum- 
ference of  the  iris  and  to  the  sclerotic  and  choroid  coats.  The  pro- 
cesses alone  are  covered  with  epithelial  cells,  and  the  intervals 
between  the  .processes  form  small  spaces,  the  spaces  of  Fontana, 
which  communicate  freely  with  the  fluid  of  the  aqueous  chamber. 
In  the  sclerotic  coat,  close  to  its  junction  with  the  cornea,  is 
situated  a  small  oval  canal,  lined  with  epithelium,  termed  the  sinus 
circularis  iridis  or  canal  of  Schlemm  (fig.  198).  Although,  by  some, 
it  is  considered  a  lymph-space,  it  is  probably  a  venous  sinus,  for 
it  can  be  injected  from  the  arteries ;  but  it  has  probably  some 
free  communication  with  the  fluid  of  the  anterior  chamber,  as  this 
fluid  passes  readily  from  the  chamber  into  this  sinus.1 

The  epithelial  lining  -consists  of  a  single  layer  of  polygonal 
nucleated  cells,  and  lines  the  inner  surface  of  the  posterior  elastic 
lamina.  They  resemble  those  which  line  serous  membranes 
generally. 

Arteries  and  nerves.— In  the  healthy  condition  the  cornea  con- 
tains no  blood-vessels,  except  at  its  circumference,  where  they  form 
loops.  Nor  have  any  lymphatics  been  demonstrated  in  it.  Its 
nerves,  which  are  numerous — forty  to  forty -five  in  number — are 
derived  from  the  ciliary  nerves,  and  may  be  traced  forwards  to  the 
fibrous  portion  of  the  cornea,  where  they  lose  their  dark  outline  and 
become  transparent,  forming  a  fine  plexus — the  primary  plexus. 
This  gives  off  minute  filaments  which  ramify  beneath  the  epithe- 
lium, constituting  the  secondary  or  sub-epithelial  plexus.  From 

1  For  further  information  on  this  point  consult  Leber,  ArcMv  f.  Opth.  1878 ; 
Heisrath,  Archiv  f.  Opth.  xxvi. ;  and  Schwalbe,  Graefe,  and  Saemisch's  Handbook, 
1874. 


800  CHOROID   COAT. 

this  very  minute  varicose  fibres  run  between  the  epithelial  cells, 
forming  the  inira-epithelial  plexus.  Besides  these  plexuses,  fila- 
ments are  given  off  from  the  primary  plexus  to  supply  the  cornea 
proper,  and  the  filaments  are  said  by  some  to  be  continuous  with 
the  anastomosing  processes  of  the  cell-spaces. 

After  the  removal  of  the  sclerotic  coat  and  the 
CHOEOID  COAT.  ,  .  ,  ...          ,,       ,, 

cornea,  which  constitute  the  first  tunic,  we  expose 

the  second  tunic,  consisting  of  the  choroid,  the  iris,  and  ciliary 
processes  in  front,  and  of  the  ciliary  ligament  and  the  ciliary 
muscle. 

The  clioroid  is  the  soft  and  flocculent  tunic  of  the  eye,  recog- 
nised by  its  dark  brown  colour  and  great  vascularity.  It  covers 
the  posterior  five-sixths  of  the  globe,  and  is  thickest  posteriorly, 
where  there  is  a  circular  aperture  in  it  for  the  passage  of  the  optic 
nerve.  In  front,  the  choroid  passes  beneath  the  ciliary  muscle  and 
ligament  with  which  it  is  connected,  and  then  extends  forwards, 
terminating  in  a  series  of  plaited  folds,  called  the  ciliary  processes. 
It  is  connected  with  the  sclerotic  by  delicate  connective  tissue,  the 
lamina  fusca,  through  which  the  ciliary  vessels  and  nerves  pass 
forwards  (fig.  199)  to  the  iris.  Its  inner  surface  is  smooth,  and  is 
in  contact  with  the  retina,  and  when  detached  from  it  presents  a 
layer  of  hexagonal  pigmented  cells,  which  are  now  recognised  as 
forming  a  part  of  the  retinal  coat  and  as  part  of  which  it  is  originally 
developed . 

Under  the  microscope  the  choroid  is  seen  to 
consist  of  two  layers,  an  external  and  an  internal. 
The  choroid  is  covered  externally  by  a  connective  tissue  layer, 
similar  to  the  lamina  fusca  of  the  sclerotic,  and  known  as  the  lamina 
supra-choroidea ;  it  consists  of  connective  tissue  intermingled  with 
elastic  tissue,  and  embedded  in  the  meshwork  are  pigment-cells 
and  lymphoid  cells.  The  contiguous  surfaces  of  the  lamina  fusca 
and  the  lamina  supra-choroidea  are  lined  with  squamous  epithelium, 
having  between  them  a  more  or  less  complete  lymph-space,  which 
is  continuous  with  that  of  Tenon's  capsule  through  the  apertures 
in  the  sclerotic,  through  which  the  ciliary  vessels  and  nerves  pass. 

The  external  layer  consists  of  the  larger  branches  of  the  blood- 
vessels ;  the  arteries  (short  ciliary)  running  forwards  between  the 


CILIARY   PROCESSSES. 


801 


veins,  previous  to  dipping  down  to  form  the  internal  layer.  The 
veins  are  arranged  with  great  regularity  in  drooping  branches 
(vence  vorticosce)  like  a  weeping  willow  (fig.  199),  and  converge  to 
four  or  five  nearly  equidistant  trunks,  which,  after  running  back- 
wards for  a  short  distance,  perforate  the  sclerotic  not  far  from  the 
entrance  of  the  optic  nerve,  and  empty  themselves  into  the  oph- 
thalmic vein.  Between  the  veins  there  are  interspersed  numerous 
stellate  pigment-cells  which  anastomose  with  neighbouring  cells ; 
on  the  inner  side  of  this  layer  the  cells  are  absent. 

The  internal  layer  is  formed  by  the  capillaries  of  the  ciliary 
arteries  and  is  called  the  tunica  Ruyschiana,  after  the  Dutch  anato- 

FIG.  199. 


SCLEROTIC   COAT   REMOVED   TO    SHOW   THE    CHOROID,    CILIARY    MUSCLE,    AND   NERVES. 

mist  Ruysch.  The  capillaries  branch  off  from  the  choroid  vessels 
in  a  radiating  manner,  and  form  the  most  delicate  vascular  net- 
work found  in  any  tissue.  It  extends  forwards  as  far  as  the 
retina,  where  the  intervals  become  larger  and  the  vessels  freely 
communicate  with  those  of  the  ciliary  processes.  This  tissue  has 
on  its  inner  surface  a  transparent  membrane,  the  membrane  of 
Bruch,  which  rests  on  the  pigmentary  layer  of  the  retina. 

CILIARY  The  ciliary  p)-ocesses  are  the  plaited  folds  formed 

PROCESSES.  by  the  anterior  part  of  the  choroid,  and  may  be 

best  seen  when  the  globe  has  been  divided  by  a  transverse  vertical 

3F 


802  CILIARY   MUSCLE. 

section  into  an  anterior  and  a  posterior  half,  the  vitreous  humour 
being  left  undisturbed.  They  are  black,  and  consist  of  from  sixty  to 
seventy  radiating  folds  arranged  in  a  circle  about  three  lines  broad. 
These  processes  consist  of  longer  and  shorter  folds,  the  former 
being  the  more  numerous,  and  in  the  proportion  of  three  to  one  of 
the  latter.  The  longer  fold  is  about  yV^h  °f  an  incn  in  length ; 
the  smaller  about  -^th  of  an  inch.  One  of  the  longer  processes 
is  seen  in  the  diagram.  The  processes  fit  into  corresponding  folds 
of  the  suspensory  ligament  of  the  lens,  and  their  free  ends  pro- 
ject for  a  short  distance  into  the  posterior  chamber.  The  circum- 
ference of  the  processes  are  attached  to  the  ciliary  ligament ;  their 
inner  ends  are  free  and  rest  upon  the  circumference  of  the  lens. 

The  vascular  supply  of  the  ciliary  processes  is 
most  abundant  and  resembles  in  the  main  that  of 
the  choroid,  except  that  the  plexus  is  coarser,  with  its  meshes 
arranged  longitudinally.  The  arteries  come  chiefly  from  the  ante- 
rior ciliary,  and  from  the  front  vessels  of  the  choroid ;  and  after 
breaking  up  into  a  fine  plexus,  they  form  loops  which  arch  back- 
wards, to  end  in  the  smaller  veins.  Their  dark  colour  is  due  to 
several  layers  of  pigmented  cells,  which  disappear,  however,  at  the 
free  ends  of  the  processes. 

The  ciliary  muscle  consists  of  unstriped  mus- 
CILIABY  MUSCLE.         ,        £,  -.    „  -.  , 

cular  fibres,  and  forms  a  muscular  zone  at  the 

front  of  the  choroid  close  to  the  junction  of  the  sclerotic  with 
the  cornea.  It  arises  by  a  thin  tendon  from  the  sclerotic  close  to 
the  cornea,  and  near  the  spaces  of  Fontana.  Thence  some  of  its 
fibres  radiate  backwards,  forming  the  meridional  or  radiating  fibres, 
and  are  lost  in  the  choroid  behind  the  ciliary  processes :  some  of 
the  fibres  form  a  circular  muscle  around  the  outer  circumference 
of  the  iris,  the  circular  ciliary  muscle,  which  was  formerly  described 
as  the  ciliary  ligament.  Its  action  is  to  accommodate  the  eye  to 
objects  at  various  distances  by  compressing  the  lens  and  increasing 
the  convexity  of  its  anterior  surface.1 

The  iris  is  the  contractile  and  coloured  curtain 
suspended  in  the  clear  fluid  which  fills  the  space 

1  Sir  P.  Crampton  has  noticed  that  this  muscle  is  well  developed  in  birds.     In 
them,  its  muscles  are  of  the  striped  variety,  as  are  the  circular  fibres  of  the  iris. 


IRIS.  803 

between  the  cornea  and  the  lens.  The  iris  divides  this  space  into 
two  unequal  parts,  called  the  anterior  and  posterior  chambers 
(fig.  198) ;  these  communicate  with  each  other  through  a  circular 
aperture  in  the  centre  of  the  iris,  called  the  pupil,  which  is  situated 
a  little  to  the  inner  side  of  the  iris.1 

.  The  circumference  of  the  iris  is  nearly  circular,  and  is  immove- 
ably  connected  with  the  choroid,  the  ciliary  muscle,  and  through 
the  ligamentum  pectinatum  with  the  cornea.  The  diameter  of  the 
iris  is  about  half  an  inch,  and  that  of  the  pupil  in  man  varies  from 
the  -JWth  to  the  ^rd  of  an  inch. 

%  O  o 

The  colour  of  the  iris  varies  in  different  subjects,  and  gives  the 
peculiar  tint  and  brilliancy  to  the  eye.  The  colouring  matter  or 
pigment  is  contained  in  minute  cells,  pigment  cells,  lining  the 
anterior  and  posterior  surfaces  of  the  iris,  the  posterior  taking  the 
name  of  uvea,  from  its  grape-like  colour.  Pigmented  cells  are  also 
found  in  the  substance  of  the  iris. 

The  use  of  the  iris  is  to  regulate  the  amount  of  light  which 
shall  be  admitted  into  the  eye ;  for  this  purpose  its  inner  circum- 
ference is  capable  of  dilating  and  contracting  according  to  circum- 
stances, while  its  outer  circumference  is  immoveably  attached. 

When  the  iris  is  laid  under  water,  and  viewed 
STRUCTURE.  .  ,         ,  .P  .  ...  , 

with  a  low  magnifying   power,  it  is  seen  to    be 

composed  of  fine  fibres  converging  from  all  sides  towards  the  pupil ; 
many  of  them  unite  and  form  arches,  leaving  elongated  interspaces, 
which  are  most  marked  towards  the  middle  of  the  iris. 

In  front  of  the  iris  is  a  thin  layer  of  polyhedral  cells,  which  is 
continuous  with  that  covering  the  membrane  of  Descemet,  but  the 
cells  are  smaller  and  more  granular. 

The  stroma  consists  of  connective  tissue  and  cells.  The  fibres 
of  the  connective  tissue  are  arranged  longitudinally  and  circularly ; 
the  longitudinal  fibres  radiate  from  the  circumference  towards 
the  pupil,  and  between  them  are  contained  the  blood-vessels  and 
nerves  ;  the  circular  fibres  are  found  at  the  circumference  of  the 
iris.  Intermingled  in  the  meshes  of  this  connective  tissue  and 

1  The  size  and  shape  of  the  pupil  vary  in  different  animals.  In  the  bullock, 
sheep,  horse,  &c.,  it  is  oblong ;  in  carnivorous  quadrupeds  it  is  often  a  mere  vertical 
slit  during  the  day,  but  dilates  into  a  large  circle  at  night. 

3  F  2 


804  STRUCTURE   OF  THE   IRIS. 

throughout  its  whole  thickness  are  numerous  and  various-shaped 
pigment  cells  having  anastomosing  processes,  like  those  of  the 
choroid.  They  are  chiefly  found  in  the  uvea,  which  is  continuous 
with  the  pigmented  layer  of  the  retina.  Upon  the  disposition  of 
these  pigment-cells  depends  the  colour  of  the  iris :  in  dark  eyes, 
the  pigment-cells  are  scattered  throughout  the  thickness  of  the 
stroma ;  in  light  eyes,  only  on  its  posterior  surface. 

The  muscular  tissue  is  of  the  unstriped  kind,  and  is  arranged 
partly  in  a  radiating,  partly  in  a  circular  manner.  The  circular 
fibres,  the  sphincter,  well  marked,  are  collected  on  the  posterior 
aspect  of  the  pupillary  margin,  where  they  form  a  ring  about  -^th 
of  an  inch  in  width ;  at  the  free  margin  of  the  iris  they  form  a 
thick  bundle,  but  become  more  frayed  out  towards  the  circum- 
ference.1 The  radiating  fibres,  the  dilatator,  converge  towards  the 
pupil,  where  they  form  arches  and  blend  with  the  circular 
fibres. 

The  pigment,  as  before  described,  is  found  in  varying  thickness 
and  position,  differing  according  to  the  colour  of  the  iris. 

The  arteries  of  the  iris  are  derived  from  the  two  long  and  the 
anterior  ciliary  arteries.  The  long  ciliary  arteries  perforate  the 
sclerotic  coat  on  each  side  of  the  optic  nerve,  and  then  run  forwards 
between  this  tunic  and  the  choroid  to  the  ciliary  muscle  at  the 
outer  circumference  of  the  iris.  Each  artery  divides  into  an  upper 
and  a  lower  branch,  which  form  with  each  other  and  the  anterior 
ciliary  arteries  a  vascular  circle  (circulus  major) ;  from  this  circle 
numerous  small  branches  pass  inwards  and  form  another  circle 
(circulus  minor)  of  anastomosis,  which  terminates  in  the  veins  of  the 
iris.  The  anterior  ciliary  arteries,  five  or  six  in  number,  are  derived 
from  the  muscular  and  lachrymal  branches  of  the  ophthalmic 
artery,  and  ramify  on  the  tendons  of  the  recti  muscles  (p.  796), 
where  they  pierce  the  sclerotic  about  the  -jVth  of  an  inch  behind 
the  margin  of  the  cornea.  These  vessels  supply  the  ciliary  pro- 
cesses and  iris,  and  join  the  circulus  major :  it  is  from  their  en- 
largement that  the  red  zone  round  the  cornea  is  produced  in 
inflammation  of  the  iris. 

1  The  circular  fibres  of  the  iris  in  the  bird  are  of  the  striped  variety,  and 
discernible  without  difficulty. 


RETINA.  805 

The  veins  follow  the  same  arrangement  as  the  arteries,  and 
communicate  as  stated  (p.  799)  with  the  canal  of  Schlemm. 

The  nerves  of  the  iris  come  from  the  nasal  branch  of  the  ophthal- 
mic nerve,  and  by  twelve  to  fifteen  branches  from  the  lenticular 
ganglion.  They  pierce  the  sclerotic  around  the  entrance  of  the 
optic  nerve,  and  run  forwards  between  the  sclerotic  and  the  choroid 
as  far  as  the  ciliary  muscle.  On  the  choroid  they  form  a  gangliated 
plexus  which  lies  in  connection  with  and  among  the  blood-vessels. 
In  the  ciliary  muscle  the  nerves  form  another  plexus,  from  which 
numerous  non-medullated  fibrils  are  given  off  to  terminate  in  the 
muscular  tissue  of  the  iris.  The  sphincter  iridis  is  supplied  through 
the  motor  root  of  the  lenticular  ganglion  which  is  derived  from  the 
third  nerve ;  the  dilatator  iridis  is  supplied  by  the  sympathetic 
system. 

MEMBBANA  Until  the  seventh  or   eighth  month   of  foetal 

PUPILLABIS.  life,  the  pupil  is  closed  by  a  transparent,  vascular 

membrane,  the  membrana  pupillaris,  so  that  the  anterior  and 
posterior  chambers  are  divided  from  each  other  by  this  membrane. 
Its  vessels,  derived  from  those  of  the  iris  and  capsule  of  the  lens, 
are  arranged  in  loops  which  converge  towards  the  centre  of  the 
membrane  without  joining  each  other.  About  the  eighth  month 
this  membrane  becomes  gradually  absorbed,  so  that  at  birth  it  is 
completely  lost. 

To  obtain  a  view  of  the  retina,  the  choroid  coat 
must  be  carefully  removed  while  the  eye  is  under 
water ;  this  should  be  done  with  the  forceps  and  scissors  on  a  fresh 
eye.  When  the  choroid  is  thus  removed,  there  will  be  seen  on  its 
inner  surface  a  layer  of  pigmented  cells,  which  has  been  already 
referred  to  as  really  the  external  layer  of  the  retina,  and  not  in  any 
way  part  of  the  choroid  coat.  The  optic  nerve,  having  entered  the 
interior  of  the  globe  through  the  sclerotic  and  the  choroid,  expands 
into  the  delicate  nerve  layer,  called  the  retina,  which  forms  the 
third  tunic  of  the  globe.  The  retina  is  in  contact,  externally,  with 
the  choroid ;  internally,  with  the  hyaloid  membrane,  which  sepa- 
rates it  from  the  vitreous  ;  and  it  extends  forwards  nearly  to  the 
posterior  margin  of  the  ciliary  processes,  where  it  terminates  in  a 
thin  serrated  border — the  or  a  serrata ;  from  this  border  a  thin 


806  STRUCTURE   OF   THE   RETINA. 

membrane — pars  ciliaris  retinae — destitute  of  nerve  fibres,  is  con- 
tinued forwards  to  the  tips  of  the  ciliary  processes,  and  thence  to 
the  posterior  surface  of  the  iris. 

In  passing  through  the  coats  of  the  eye,  the  optic  nerve  becomes 
gradually  constricted  and  reduced  to  one-half  of  its  diameter  ;  here 
it  presents  a  round  disc,  called  the  porus  options,  in  the  centre  of 
which  may  be  seen  the  arteria  centralis  retinse.  At  this  point,  too, 
the  nerve-substance  projects  slightly  into  the  interior  of  the  globe, 
forming  a  little  prominence,  to  which  the  term  colliculus  nervi 
optici  has  been  applied.  This  prominence  is  remarkable,  in  that  it 
is  insensible  to  the  rays  of  light,  and  is  hence  called  the  '  blind 
spot.' 

The  retina  when  fresh  is  nearly  transparent,  but  soon  it  becomes 
of  a  pink  milky  tint.  Precisely  opposite  the  pupil,  in  the  centre 
of  the  axis  of  vision,  there  is  an  oval  yellow  spot,  macula  lutea,  in 
the  retina,  about  ^-th  of  an  inch  in  diameter,  having  a  depression, 
fovea  centralis,  in  the  centre,  and  fading  oft7  gradually  at  the  edges. 
Here  vision  is  most  perfect,  so  that  it  might  be  called  the  '  spot 
of  light.'  This  central  spot  was  believed  by  its  discoverer, 
Sommering,  to  be  a  perforation ;  but  it  is  now  ascertained  to  be 
due  to  the  pigmentary  layer  of  the  retina  showing  through  it. 
These  appearances  are  lost  soon  after  death,  and  are  replaced  by  a 
minute  fold,  into  which  the  retina  gathers  itself,  reaching  from  the 
centre  of  the  spot  to  the  prominence  of  the  optic  nerve.1 

Although  to  the  naked  eye  the  retina  appears 
a  simple,  soft,  semi-transparent  membrane,  yet 
when  examined  under  the  microscope  it  is  found  to  be  most 
minutely  and  elaborately  organised.  It  varies  in  thickness  from 
the  sV^  to  ^6  -j-J-oth  of  an  inch,  being  thickest  behind,  and 
gradually  diminishes  towards  the  front.  It  consists  of  eight 
layers,  through  which  may  be  traced  a  considerable  amount  of 
extremely  delicate  connective  tissue  (fibres  of  Miiller),  which  con- 
stitutes a  sustentacular  tissue  for  the  various  strata,  and  is  said  to 
form  for  them  two  more  or  less  continuous  boundary  layers,  termed 
membrance  limitantes,  interna  and  externa,  and  which  are  classed  by 

1  In  birds  the  retina  has  throughout  the  yellowish  colour  seen  only  at  one  par 
in  the  human  eye. 


STRUCTURE   OF  THE  RETINA.  807 

some  anatomists  as  two  additional  layers.     The  layers  of  the  retina 
are  as  follows,  beginning  from  within  : — 

1.  The  layer  of  nerve-fibres. 

2.  The  ganglionic  layer. 

3.  The  inner  molecular  layer. 

4.  The  inner  nuclear  layer. 

5.  The  outer  molecular  layer. 

6.  The  outer  nuclear  layer. 

7.  The  layer  of  rods  and  cones. 

8.  The  pigmentary  layer. 

The  membranae  limitantes  are  situated  as  follows  :  the  internal 
stratum  lies  on  the  inner  surface  of  the  layer  of  nerve-fibres  ; 
the  external,  between  the  outer  nuclear  layer  and  the  layer  of 
rods  and  cones. 

1.  The  layer  of  nerve-fibres  (fig.  200,  i)  is  composed  of  the  spread- 
ing out  of  the  optic  nerve-fibres,  and  of  connective  tissue  cells. 
The  nerve-fibres,  consisting  only  of  the  axis-cylinders,  run  for- 
wards as  a  continuous  layer  to  the  ora  serrata,  partly  arranged  in 
bundles  and  partly  in  plexuses,  and  become  connected  with  the 
nerve-cells  of  the  next  layer.     The  fibres  are  almost  absent  on  the 
yellow  spot. 

2.  The  ganglionic  layer  (fig.  200,  2)  is  a  stratum  of  spheroidal 
nerve-cells ;  from  the  deeper  part  of  each  cell  there  is  given  off  a  single 
elongated  process,  which  passes  obliquely  into  the  nerve-fibre  layer, 
with  which  it  becomes  continuous ;  from  the  outer  side  of  the  cell 
two  or  more  processes  are  given  off,  which  branch  dichotomously 
and  become  at  first  embedded  and  then  lost  in  the  inner  molecular 
layer.      The  ganglionic   cells,  which  in  the  greater  part  of  the 
stratum  form  a  single  layer,  are  at  the  yellow  spot  arranged  eight 
or  ten  deep,  and  in  its  neighbourhood  two  or  three  deep. 

3.  The  inner  molecular  layer  (fig.  200,  3)  is  a  granular  stratum  of 
considerable  thickness  which  exhibits,  under  high  powers,  a  reticu- 
lar  structure,  having  small  interstices  filled  probably  with  lymph. 
In  it  are  found,  the  processes  of  the  nerve-cells  of  the  preceding 
layer,  which  pass  outwards  for  a  considerable  distance ;  some  vari- 
cose filaments  which  pass  inwards  from  the  next  layer  ;  and  some 
Mullerian  fibres  which  pass  through  this  layer.     Other  cells,  like 


808 


STRUCTUKE   OF  THE   RETINA. 


those  found  in  the  nerve-fibre  and  ganglionic  layers,  are  also  found 
in  this  stratum,  chiefly  on  its  surfaces. 

4.  The  inner  nuclear  layer  (fig.  200,  4)  contains  three  kinds  of 
cells,  and  some  fibres  which  belong  to  the  Miillerian  or  connective 
tissue  fibres  of  the  retina.  The  first  kind  consists  of  oval  bipolar  cells 


FIG.  200. 


8.  Layer  of  pigment  cells. 


7.  Layer  of  rods  and  cones. 
(Membrana  Jacobi.) 

Membrana  limitans  ext. 


6.  Outer  nuclear  layer. 


5.  Outer  molecular  layer. 


4.  Inner  nuclear-layer. 


3.  Inner  molecular-layer. 


2.  Layer  of  nerve-cells. 

1.  Layer  of  nerve-fibres. 

Membrana  limitans  interna. 

DIAGBAM   OF   THE    VARIOUS   LAYERS   OF   THE    RETINA.       (AFTER   SCHWALBE.) 

placed  longitudinally,  and  having  a  distinct  nucleus  and  nucleolus  ; 
from  the  inner  extremities  of  these  cells  there  extend  long  vari- 
cose, thin  processes  which  pass  vertically  downwards,  without 
division,  into  the  inner  molecular  layer,  and  are  presumably  con- 
nected with  the  processes  of  the  ganglionic  layer  and  thence  with 


STRUCTURE    OF   THE   RETINA.  809 

the  nerve-fibres ;  from  the  outer  extremities  of  the  cells  pass  pro- 
cesses, thicker  than  the  ones  just  described  and  not  varicose,  which 
pass  to  the  next  layer  and  there  break  up  into  numerous  filamentous 
processes.  The  second  kind  of  cells  are  small,  granular,  proto- 
plasmic cells,  which  are  confined  to  the  deeper  part  of  this  layer ; 
and  the  third  kind,  similar  in  their  appearance,  are  disposed  here 
and  there  in  the  most  external  stratum  of  the  inner  nuclear  layer. 
The  course  which  the  Mtillerian  fibres  take  through  this  layer  will 
be  described  later  on. 

5.  The  outer  molecular  or  internuclear  layer  (fig.  200,  5)  resembles 
in  most  respects  the  inner  molecular  layer,  but  is  much  thinner. 
It  contains,  however,  numerous  flattened,  branched  cells,  having 
well-marked  nuclei  and  nucleoli,  and  whose  fine  branching  pro- 
cesses exhibit  varicosities  in  their  course,  resembling  nerve-fibrils. 
Whether  these  are  nerve-fibres  or  only  the  fibres  of  the  sustentacular 
tissue  is  at  present  not  determined ;  but  this  layer,  as  well  as  those 
already  described,  is  developed  in  the  same  manner  as  those  of  the 
brain,  so  that  probably  these  fibres  are  nerve-fibrils. 

6.  The   outer  nuclear  layer  (fig.   200,   e)  consists  of  a  thick 
stratum  of  nucleated  cells,  having  outward  and  inward  prolonga- 
tions, which  may  be  recognised  as  connected  respectively  with  the 
rods  and  cones  of  the  next  layer.     The  rod-granules  are  the  most 
numerous,  and  each  presents  an  oval  cell,  which  has  a  well-marked 
transverse  striation,  due  to  the  highly  refracting  substance  being 
crossed  by  discs  of  a  less  refracting  medium.    There  are  usually  two, 
one  on  each  side  of  the  middle  of  the  cell.     From  this  enlargement 
one  varicose  filament  passes  inwards  and  becomes  connected  with  the 
outer  molecular  layer  by  a  dilatation,  from  which  numerous  fila- 
ments pass  inwards  ;  the  other  extremity  is  thicker,  not  varicose, 
and  passes  outwards  towards  the  membrana  limitans  externa,  where 
it  becomes  somewhat  expanded,  and  then  becomes  continuous  with 
a  rod.    The  cone-granules  are  fewer,  and  each  has  an  oval  nucleated 
cell,  which  presents  no  transverse  striation  characteristic  of  the 
rod-granule.     The  cell  is  situated  close  to  the  membrana  limitans 
externa,  and  rests  upon  a  thick  cone-fibre,  much  thicker  than  a 
rod-fibre,  which  enlarges  as  it  approaches  the  outer  molecular  layer, 
upon  which  it  rests  by  a  pyramidal  base.   From  this  base  numerous 


810  STRUCTURE   OF  THE   RETINA. 

fine  processes  are  given  off  into  the  molecular  layer :  the  outer 
extremity  is  very  short  and  broad,  and  supports  the  base  of  a  cone. 

7.  The  layer  of  rods  and  cones,  bacillary  layer  or  Jacob's  mem- 
brane (fig.  200,  7)  is   composed  of  minute   cylindrical  elements, 
arranged  at  right  angles  to  the  surface  of  the  retina.     The  rods, 
the  more  numerous,  are  tapering  processes  running  through  the 
whole  thickness  of  this  layer,  and,  externally,  are  embedded  to  a 
greater  or  less  depth  in  the  pigmented  layer,  so  that  when  viewed 
from  without  they  have  the  appearance  of  mosaic  pavement  made 
up  of  round  segments.     Among  the  rods  are  intermingled  nume- 
rous shorter,  flask-shaped  bodies  called  cones,  which  do  not  extend 
through  more  than  half  the  thickness  of  this  layer.     Their  outer 
extremities  taper  off  towards  the  choroid ;  their  inner  or  broad  ends, 
like  the  rods,  rest  upon  the  membrana  limitans  externa,  and  thence 
are  connected  with  the  outer  nuclear  layer.     Each  rod  and  cone 
consists  of  two  segments  of  equal  lengths  :  the  inner,  in  the  case 
of  the  cones,   very  broad   and   bottle-shaped,    of  the   rods   only 
slightly  bulged ;  the  outer,  fine  and  tapering  off.   The  two  segments 
vary  in  their  microscopic  appearance  and  in  relations  to  reagents ; 
the  outer  segments  of  both  have  a  transverse  striation,  and  break 
up  in  the  direction  of  this  striation ;  the  inner  segments  are  com- 
posed externally  of  longitudinal  fibrillae,  internally  of  finely  granular 
homogeneous  substance  continuous   with  the   rod  or   cone  fibre. 
The  inner  segments  are  deeply  stained  by  carmine,  iodine,  &c.,  the 
outer  segments  not  by  the  same  reagents,  but  are  by  osmic  acid. 
The  rods  are  absent  at  the  yellow  spot. 

8.  The  pigmentary  layer  (fig.  200,  8)  is  usually  described  as 
forming  part  of  the  choroid  coat,  but  it  should  both  development- 
ally  and  physiologically  be  included  as  one  of  the  layers  of  the 
retina.     It  consists  of  a  single  layer  of  hexagonal  nucleated  cells 
filled  with  pigment-granules,  which  are  most  numerous  towards  the 
margins  of  the  cells.     The  surface  of  the  cells  which  looks  towards 
the  choroid  is  smooth  and  destitute  of  pigment-granules,  and  it  is 
here  that  the  nucleus  is  situated;   the  surface   towards   Jacob's 
membrane  is  filled  with  pigment,  which  is  not  well  defined,  but 
runs  down  among  the  rods,  so  that  their  outer  part  is  embedded 
among  the  pigment-cells.     The  use  of  the  pigment  is  to  absorb  the 


STRUCTURE   OF  THE   RETINA.  811 

rays  of  light  which  pass  through  the  retina,  and  thus  prevent 
their  being  reflected.  It  serves  the  same  purpose  as  the  black 
paint  with  which  the  inside  of  optical  instruments  is  darkened. 
Albinoes,  in  whom  this  layer  has  little  or  no  pigment,  are, 
consequently,  dazzled  by  daylight  and  see  better  in  the  dusk.1 

The  sustentacular  tissue  (Miillerian  fibres)  is  a  tissue  which 
runs  through  the  greater  thickness  of  the  retina,  beginning  at  the 
so-called  membrana  limitans  interna,  and  ending  at  the  membrana 
limitans  externa;  but  in  neither  of  these  two  situations  does  it 
form  a  continuous  layer,  so  that  it  cannot  be  classed  under  the 
layers  forming  the  retina.  These  fibres  are  probably  of  the  nature 
of  a  delicate  connective  tissue,  which  serves  to  sustain  the  various 
layers  and  their  constituent  elements.  Each  fibre  begins  by  a 
broad  conical  base,  on  the  deeper  aspect  of  the  layer  of  nerve- 
fibres  (the  bases  of  these  fibres  being  more  or  less  in  connection 
with  each  other)  ;  it  then  passes  through  the  layers  of  nerve-fibres 
and  ganglionic  cells,  and,  consequently,  the  inner  molecular  layer, 
gradually  diminishing  in  thickness ;  on  reaching  the  inner  nuclear 
layer  it  gives  off  thin  filamentous  processes  which  support  the 
structures  of  this  stratum,  presenting  here  a  lateral  bulge  with  a 
well-marked  nucleus.  After  passing  through  the  outer  molecular 
layer  it  reaches  the  outer  nuclear  layer,  and  then  breaks  up  into 
filaments  which  join  with  fibrils  from  other  Miillerian  fibres,  thus 
enclosing  and  supporting  the  cells  and  their  prolongations  of  this 
layer.  These  filamentous  offsets  reach  as  far  as  the  bases  of  the 
rods  and  cones,  forming  a  bed  on  which  they  rest ;  this  is  described 
as  the  membrana  limitans  externa. 

The  structure  of  the  macula  lutea  and  fovea  centralis. — In  the 
macula  lutea,  the  nerve-fibres  do  not  form  a  continuous  layer ;  the 
ganglionic  layer  consists  of  cells  six  to  eight  deep ;  there  are  no 
rods ;  the  cones  are  longer  and  narrower  than  elsewhere ;  and  the 
outer  nuclear  layer  has  only  cone-fibres.  In  the  fovea  centralis 

1  In  many  of  the  nocturnal  carnivorous  quadrupeds,  the  inner  surface  of  the 
choroid  at  the  bottom  of  the  eye  presents  a  brilliant  colour  and  metallic  lustre.  It 
is  called  the  tapetum.  By  reflecting  the  rays  of  light  a  second  time  through  the 
retina,  it  probably  enables  the  animal  to  see  better  in  the  dusk.  It  is  the  cause  of 
the  well-known  glare  of  the  eyes  of  cats  and  other  animals  ;  and  the  great  breadth 
of  the  luminous  appearance  arises  from  the  dilatation  of  the  pupil. 


812  AQUEOUS   HUMOUK. 

there  are  no  rods,  and  the  cones  are  longer  than  in  the  macula  ; 
and  all  the  other  layers  are  much  thinned.  At  the  margin  of  the 
fovea  most  of  the  layers  are  thicker  than  elsewhere. 

The  structure  of  the  ora  serrata  is  much  less  complex  than 
the  other  parts  of  the  retina  ;  the  layer  of  rods  and  cones  dis- 
appear, the  former  first  of  all ;  the  ganglionic  and  nerve-fibre  layers 
become  thin  and  then  cease ;  the  inner  molecular  layer  loses  much 
of  its  granular  appearance,  and  is  largely  formed  of  sustentacular 
tissue,  and  then  abruptly  ceases;  the  inner  and  outer  nuclear 
layers  become  thinner,  and  then  gradually  merge  into  a  single 
layer,  which  is  continued  on  to  the  pars  ciliaris  as  a  single  stratum 
of  columnar  epithelial  cells. 

The  arteria  centralis  retince,  after  emerging  through  the  porus 
opticus,  divides  into  two  branches — an  upper  and  a  lower — which 
then  form  a  delicate  network  of  blood-vessels  throughout  the  nerve- 
fibre  layer,  penetrating  as  far  as  the  inner  nuclear  layer,  beyond 
which  no  capillaries  can  be  traced.  After  maceration  in  water, 
the  nervous  substance  can  be  removed  with  a  camel's-hair  brush, 
and  then  in  an  injected  eye  the  network  formed  by  the  vessels  can 
be  distinctly  seen.  The  arteries  of  the  retina  do  not  communicate 
directly  with  the  choroidal  vessels. 

AQUEOUS  The  aqueous  humour  consists  of  a  few  drops  of 

HUMOUR.  an  alkaline  clear  watery  fluid,  which  fills  the  space 

between  the  cornea  and  the  lens.1  The  iris  lies  in  it,  and  divides 
the  space  into  two  chambers  of  unequal  size — an  anterior  and  a 
posterior.  The  posterior  is  much  the  smaller  of  the  two  ;  indeed, 
the  iris  rests  on  the  capsule  of  the  lens,  so  that,  strictly  speaking, 
there  is  no  interval  between  the  opposed  surfaces,  except  a  triangular 
interval  bounded  by  the  attachment  of  the  iris,  the  ciliary  processes, 
and  the  zone  of  Zinn.  This  accounts  for  the  frequent  adhesions 
which  take  place  during  inflammation  of  the  iris,  between  the  iris 
and  the  capsule  of  the  crystalline  lens.2  A  delicate  layer  of  epithe- 
lium covers  the  posterior  surface  of  the  cornea,  but  nothing  like  a 
continuous  membrane  can  be  demonstrated  on  the  iris  or  the  capsule 

1  The  solid  constituent  is  mainly  composed  of  chloride  of  sodium. 

2  Some  anatomists  describe  the  anterior  chamber  as  lined  by  a  serous  mem- 
brane called  the  membrane  of  the  aqueous  humour. 


VITREOUS   BODY.  813 

of  the  lens.  The  anterior  chamber  is  remarkable  for  the  rapidity 
with  which  it  absorbs  and  secretes  ;  as  is  proved,  in  the  one  case, 
by  the  speedy  removal  of  extravasated  blood  ;  in  the  other,  by  the 
rapid  reappearance  of  the  aqueous  humour  after  the  extraction  of  a 
cataract. 

THE  VITKEOUS  ^e  v^1"60118  body  is  a  transparent,  gelatinous- 

BODY  AND  THE  looking  substance,  which  fills  up  nearly  four-fifths 
HYALOID  MEM-  of  the  interior  of  the  globe  (p.  797).  It  can  be 
easily  separated  from  the  retina,  except  at  the 
optic  disc ;  in  front  it  presents  a  deep  depression,  in  which  the 
crystalline  lens  is  embedded.  It  is  surrounded,  except  in  front,  by 
a  delicate  transparent  membrane — the  hyaloid  membrane — which 
forms  a  capsule  for  the  vitreous  body,  and  is  sufficiently  strong  to 
keep  it  in  shape  after  the  stronger  tunics  of  the  eye  have  been 
removed. 

When  the  vitreous  humour  has  been  hardened  in  chromic  acid 
it  is  rendered  somewhat  opaque,  and  presents,  especially  at  its  outer 
part,  a  lamellar  appearance.  It  consists  of  a  fluid  contained  in  the 
meshes  of  a  cellular  structure,  which  communicate  freely  with  each 
other ;  for  if  any  part  of  it  be  punctured,  the  humour  gradually 
drains  away.1  If  examined  carefully,  the  lamellation  is  seen  to  be 
arranged  concentrically,  the  layers,  as  they  approach  the  centre, 
becoming  less  firm  in  consistence.  The  _, 

vitreous,  moreover,  on  a  transverse  section, 
shows   a  radial  striation,  but  whether  this 
exists  naturally,  or  is  the  result  of  post-mor- 
tem changes,  or  from  chemical  reagents,  is 
not  known.     Running  through  the  middle 
from  before  backwards  is  a  small  canal — canal 
of  Stilling — about  a  line  in  diameter,  which     ABTEEIES  OF  THE  RETINA. 
contains  fluid,  and  is  broader  behind  than  in       canal  of  Petit  (inflated). 
front ;  this  in  the  foetus  lodges  a  small  branch      Zone  of  zinn  (-Derated). 
of  the  retinal  artery,  which  ramifies  on  the  back  of  the  capsule  of 
the  lens. 

The  hyaloid  membrane  surrounds  the  vitreous  body,  except  in 
front,  and  passes  from  the  anterior  border  of  that  body  to  the 
1  This  is  composed  mainly  of  water,  with  albuminate  of  soda  and  mucin. 


814  CRYSTALLINE   LENS. 

margin  of  the  lens,  forming  the  suspensory  ligament  of  the  lens,  and 
known  as  the  zone  of  Zinn.  This  is  best  exposed  by  removing  the 
ciliary  processes.  It  appears  as  a  dark,  radiating  disc,  and  the 
surface  is  marked  by  prominent  ridges,  which  correspond  with  the 
intervals  between  the  ciliary  processes  (fig.  201).  These  intervals 
are  in  life  filled  with  fluid,  and  perhaps  with  the  vitreous.  The 
hyaloid  membrane,  with  the  exception  of  the  suspensory  ligament, 
is  a  structureless  membrane,  but  the  ligament  presents  a  structure 
consisting  in  part  of  longitudinal  elastic  fibres.  Beneath  the  mem- 
brane, on  its  inner  surface,  are  numerous  granular  nucleated  cells, 
which  exhibit  amosboid  movements.  The  ligament  assists  in  main- 
taining the  lens  in  its  proper  position,  and  is  firmly  connected  with 
its  capsule. 

,  If  the  transparent  membrane  between  the  zone 
of  Zinn  and  the  margin  of  the  lens  be  carefully 
punctured,  and  the  point  of  a  small  blowpipe  gently  introduced, 
and  air  or  fluid  injected,  we  may  succeed  in  inflating  a  canal  which 
encircles  the  lens  :  this  is  the  canal  of  Petit  (fig.  201).  It  is  about 
•ji^th  of  an  inch  wide,  triangular  in  section,  and  bounded  in  front 
by  the  suspensory  ligament  of  the  lens  ;  behind,  by  the  vitreous 
body ;  and  its  base,  by  the  capsule  of  the  lens.  When  inflated,  it 
becomes  sacculated,  as  in  fig.  201,  owing  to  the  foldings  on  the  front 
surface  of  the  lens. 

CRYSTALLINE  The  crystalline  lens  (fig.  198)  is  a  perfectly  trans- 

LENS.  lucent  solid  body,  situated  immediately  behind  the 

pupil,  partly  embedded  in  the  vitreous  body,  and  completely  sur- 
rounded by  a  capsule  equally  translucent.  It  is  convex  on  both 
sides,  but  more  so  behind.  In  early  life  it  is  nearly  spherical  and 
soft,  but  it  becomes  more  flattened,  firmer,  and  amber-coloured  with 
advancing  age.  In  the  adult  its  transverse  diameter  is  about  one- 
third  of  an  inch  ;  its  antero-posterior,  one-fifth  of  an  inch. 

The  capsule  of  the  lens  is  a  transparent,  elastic,  and  brittle 
membrane.  It  resembles  in  structure  the  elastic  layer  of  the 
cornea,  and  is  much  thicker  in  front  than  behind ;  in  front,  it  is  in 
contact  with  the  posterior  surface  of  the  iris ;  behind,  it  rests  in  the 
depression  of  the  vitreous  body.  The  capsule  in  front  is  separated 
from  the  lens  by  a  layer  of  polygonal  nucleated  cells,  and,  after 


STRUCTURE   OF    THE   LENS.  815 

death,  a  layer  of  fluid  is  interposed  between  the  capsule  and  the 
lens,  constituting  the  liquor  Morgagni',  behind,  no  such  layer  of 
epithelium  exists.  No  vascular  connection  whatever  exists  between 
the  lens  and  its  capsule.1  The  lens  protrudes  directly  the  capsule 
is  sufficiently  opened. 

STBUCTUKE  OF  The  minute  structure  of  the  lens  can  only  be 

THE  LENS.  made  out  after  being  hardened.     It  is  soft,  almost 

gelatinous  in  consistence  outside,  but  each  successive  concentric 
layer  becomes  more  dense,  so  that  the  central  part  is  hard,  and 
constitutes  the  nucleus.  It  is  seen  to  be  divided  into  three  equal 
parts,  by  three  lines,  which  radiate  from  the  centre  to  within  one- 
third  of  the  circumference.  Each  of  these  portions  is  composed  of 
numerous  concentric  layers,  arranged  one  within  the  other,  like 
the  coats  of  an  onion.  If  any  single  layer  be  examined  with  the 
microscope,  it  is  seen  to  be  composed  of  fibres  about  5  010  Oth  of  an 
inch  in  thickness,  running  in  a  curved  direction,  and  connected 
together  by  finely  serrated  edges.  On  a  transverse  section  the  lens- 
fibres  are  found  to  be  hexagonal  prisms,  with  very  little  connecting 
substance.  Between  the  front  of  the  lens  and  its  capsule  is  a  layer 
of  flattened  cells  with  well-marked  excentric  nuclei.  The  beautiful 
dove-tailing  of  the  fibres  of  the  lens  was  first  pointed  out  by  Sir 
David  Brewster ;  and  to  see  it  in  perfection,  one  ought  to  examine 
the  lens  of  the  cod-fish. 

The  function  of  the  lens  is  to  bring  the  rays  of  light  to  a  focus 
upon  the  retina.2 

1  The  vessel  of  the  capsule  of  the  lens  is  derived  from  the  arteria  centralis 
retinae,  and  in  mammalia  can  only  be  injected  in  the  foetal  state.     In  the  reptilia, 
however,  the  posterior  layer  of  the  capsule  is  permanently  vascular.     This  small 
artery  passes  forwards  through  the  canal  of  Stilling  to  the  posterior  part  of  the 
capsule  of  the  lens,  on  which  it  radiates  into  numerous  small  branches,  communi- 
cating with  branches  in  the  iris  and  pupillary  membrane. 

2  The  lens  contains  about  60  per  cent,  of  water,  and  30  per  cent,  of  albuminoids. 


816 


DISSECTION  OF  THE  ORGAN  OF  HEARING. 

THE  parts  constituting  the  organ  of  hearing  should  be  examined 
in  the  following  order :  (1)  the  outer  cartilage  or  pinna ;  (2)  the 
meatus  auditorius  externus;  which  leads  to  (3)  the  tympanum 
or  middle  ear ;  and  (4)  the  labyrinth  or  internal  ear,  comprising 
the  vestibule,  cochlea,  and  semicircular  canals,  which  contain  the 
distribution  of  the  auditory  nerve. 

The  pinna  or  auricle  consists  of  yellow  fibro- 

PlNNA.  „  _          .  .  .        . 

cartilage  covered  with  integument,  and  is  irre- 
gularly concave  to  receive  the  undulations  of  sound.  It  is 
unevenly  oval,  and  presents  on  its  external  aspect  numerous  emi- 
nences and  hollows,  which  have  received  the  following  names : — 
The  circumferential  folded  border  is  called  the  helix ;  the  ridge 
within  it,  the  antihelix ;  between  these  is  a  curved  groove,  called 
the  fossa  of  the  helix.  The  antihelix  bifurcates  towards  the  front, 
and  encloses  the  fossa  of  the  antihelix  (fossa  scaphoidea).  The  conical 
eminence  in  front  of  the  meatus  is  termed  the  tragus,  on  which 
some  hairs  are  usually  found.  Behind  the  tragus,  and  separated 
from  it  by  a  deep  notch  (incisura  intertragica~),  is  the  antitragus. 
The  lobule  is  the  soft  pendulous  part  placed  below  the  concha,  and 
consists  of  fat  and  fibrous  tissue.  The  deep  hollow,  which  collects 
the  vibrations  of  sound,  and  conveys  them  into  the  external  meatus, 
is  termed  the  concha. 

The  pinna  is  composed  of  yellow  fibro-cartilagfe, 
STEUCTUEE.  ,  •        ,  •  -,      .,, 

with  some  fat  and  connective  tissue,  covered  with 

integument,  and  attached  to  neighbouring  parts,  partly  by  fibrous 
tissue  and  partly  by  muscles. 

The  skin  is  very  thin,  intimately  adherent  to  the  subjacent 
cartilage,  and  provided  with  numerous  sebaceous  glands,  found 
chiefly  in  the  scaphoid  fossa  and  the  concha. 


MUSCLES   OF  THE   PINNA.  817 

The  cartilac/e  is  a  single,  uneven  plate  of  fibre-cartilage,  which 
presents  all  the  irregularities  of  the  external  ear.  The  cartilage  is 
incomplete,  for  there  is  a  deficiency  behind  the  tragus  at  the 
bottom  of  the  concha,  which  is  filled  up  with  fibrous  tissue.  It 
has  a  tubular  prolongation  inwards,  which  forms  the  external  part 
of  the  meatus  auditorius  externus.  The  cartilage  presents  several 
fissures  (fissures  of  Santorini)  at  the  anterior  part  of  the  tubular 
prolongation,  which  are  completed  by  fibrous  tissue.  In  the  front 
part  of  the  pinna,  where  the  helix  makes  its  first  bend,  is  a  conical 
projection  of  cartilage,  termed  the  process  of  the  helix.  The  lobule, 
attached  to  the  lower  part  of  the  pinna,  is  a  rounded  projection 
formed  of  fat  and  connective  tissue ;  it  is  this  which  enlarges  with 
age  and  obesity  of  the  subject. 

The  ligaments  are  :  the  anterior  liqament,  broad 
LIGAMENTS.  .  ' 

and  strong,  which  passes  from  the  process  of  the 
helix  to  the  root  of  the  zygoma;  the  posterior  ligament,  which 
extends  from  the  cranial  surface  of  the.  concha  to  the  mastoid 
process  of  the  temporal  bone.  There  are  also  intrinsic  ligaments 
which  bridge  over  and  fill  up  the  deficiencies  in  the  pinna. 

MUSCLES  OF  The  muscles  which  move  the  cartilage  of  the 

THE  PINNA.  ear    as   a   whole,  have  been  described  (page  3). 

Other  small  muscles  extend  from  one  part  of  the  cartilage  to  an- 
other ;  but  they  are  so  indistinct  that,  unless  the  subject  be  very 
muscular,  it  is  difficult  to  make  them  out.  The  following  six — 
four  on  the  front  of  the  auricle  and  two  behind  it — are  usually 
described : — 

(a)  The  musculus  major  helicis  runs  vertically  along  the  front 
margin  of  the  helix :  it  arises  below  from  the  process  of 
the  helix,  and  is  inserted  into  the  curve  of  the  helix  as  it 
passes  backwards. 

(6)  The  musculus  minor  helicis,  an  oblique  muscle,  lies  over  that 
part  of  the  helix  which  is  connected  with  the  concha. 

(c)  The  musculus  tragicus  lies  vertically  over  the  outer  surface 

of  the  tragus. 

(d)  The  musculus  antitragicus  passes  transversely  from  the  anti- 

tragus  to  the  lower  part  of  the  tail-like  process  of  the 
helix  behind  the  lobule. 

3G 


818  MEATUS  AUDITORIUS   EXTERNUS. 

(e)  The  transversus  auriculae  is  on  the  cranial  aspect  of  the 

pinna ;  it  passes  nearly  transversely  from  the  back  of 

the  concha  to  the  prominence  corresponding  to  the  fossa 

of  the  helix. 

(/)  The    obliquus    auris   extends   vertically  from   the    cranial 

aspect  of  the  concha  to  the  convexity  below  it. 
The  arteries  of  the  pinna  are  derived  from  the  posterior  auri- 
cular, and  from  the  auricular  branches  of  the  temporal  and  occipital. 
The  veins  empty  themselves  into  the  temporal  vein.  The  nerves 
are  furnished  by  the  great  auricular  branch  of  the  superficial 
cervical  plexus,  the  auriculo-temporal  branch  of  the  inferior  maxil- 
lary, the  posterior  auricular  branch  of  the  facial,  and  the  auricular 
branch  of  the  pneumogastric. 

MEATUS  AUDI-  This  oval  passage  leads  down  to  the  membrana 

TOBIUS  EXTEBNUS.  tympani,  and  conveys  the  vibrations  of  sound  to 
the  tympanum.  It  is  about  an  inch  and  a  quarter  in  length ;  its 
external  opening  is  longest  in  its  vertical  direction  :  its  termination 
is  broadest  in  its  transverse.  The  canal  inclines  at  first  upwards 

and  forwards,   and   then  curves  a  little    downwards.1     Its    floor, 

'  . 

owing  to  the  oblique  direction  of  the  membrana  tympani,  is  a  little 

longer  than  the  roof.  It  is  not  of  equal  calibre  throughout,  the 
narrowest  part  being  about  the  middle ;  hence  the  difficulty  of 
extracting  foreign  bodies  which  have  passed  to  the  bottom  of  the 
canal.  It  is  formed,  partly  by  a  tubular  continuation  of  the  car- 
tilage of  the  pinna,  partly  by  an  osseous  canal  in  the  temporal  bone. 

The  cartilaginous  portion  is  about  half  an  inch  long,  and  is 
firmly  connected  to  the  osseous  portion.  The  cartilage  is  incom- 
plete at  the  upper  and  back  part,  and  the  interval  is  filled  in  with 
fibrous  tissue. 

The  osseous  portion,  about  three-quarters  of  an  inch  in  length, 
is  narrower  than  the  cartilaginous  portion,  and  is  curved  forwards 
and  inwards.  Its  outer  extremity  is  rough  for  the  attachment  of 
the  cartilage ;  its  inner  presents  a  narrow  groove,  except  at  the 
upper  part,  for  the  insertion  of  the  membrana  tympani.  The 

1  To  obtain  a  correct  knowledge  of  the  length  and  dimensions  of  the  meatus, 
sections  should  be  made  through  it  in  different  directions,  or  a  cast  be  taken  of  it 
in  plaster-of -Paris. 


TYMPANUM.  819 

lower  and  anterior  wall  of  the  osseous  portion  is  formed  by  a  semi- 
circular plate  of  bone,  the  tympanic  plate,  the  outer  border  of  which 
is  thickened  and  is  termed  the  external  auditory  process. 

The  skin  and  the  cuticle  are  continued?  down  the  passage,  and 
becoming  gradually  thinner,  form  a  cul-de-sac  over  the  membrana 
tympani.  The  outer  portion  is  furnished  with  hairs  and  ceru- 
minous  glands,  which  secrete  the  cerumen  or  wax,  and  are  only 
found  over  the  cartilaginous  portion  of  the  canal. 

Its  arteries  are  derived  from  the  posterior  auricular,  the  internal 
maxillary  and  the  temporal,  all  branches  of  the  external  carotid 
artery.  Its  nerves  come  from  the  auriculo-temporal  branch  of  the 
inferior  maxillary  nerve. 

The  tiimpanum,  or  middle  ear,  is  an  irregular 
TYMPANUM.  .    .       .  J   £  „    ,    '  .     ° 

cavity  in  the  petrous  part  ot  the  temporal  bone : 

having  on  its  outer  side  the  membrana  tympani ;  on  its  inner  side 
the  labyrinth ;  behind,  the  mastoid  cells ;  in  front,  the  carotid 
canal ;  below,  the  wall  of  the  jugular  fossa.  It  is  rather  less  than 
half  an  inch  in  its  long  diameter ;  from  -i-th  to  -^-th  of  an  inch 
between  its  outer  and  inner  boundaries  ;  and  a  quarter  of  an  inch 
in  its  vertical  direction.  It  is  lined  with  mucous  membrane  and 
filled  with  air,  which  is  freely  admitted  through  the  Eustachian 
tube ;  so  that  atmospheric  pressure  is  equal  on  both  sides  of  the 
membrane.  A  chain  of  small  bones,  the  ossicles,  retained  in  their 
position  by  ligaments  and  acted  upon  by  muscles,  passes  across  it. 
The  use  of  these  bones  is  to  communicate  the  vibrations  of  the 
membrana  tympani  to  the  labyrinth.  For  this  purpose  one  end 
of  the  chain  is  attached  to  the  membrane,  the  other  to  the  fenestra 
ovalis.  The  tympanum  is  bounded  by  a  floor,  a  roof,  an  outer,  an 
inner,  an  anterior,  and  a  posterior  wall. 

Its  roof  is  formed  by  a  thin  plate  of  bone  corresponding 
with  the  anterior  surface  of  the  pars  petrosa,  which  separates  the 
tympanum  from  the  cranial  cavity. 

The  floor,  which  is  narrow,  is  formed  by  a  thin  plate,  corre- 
sponding to  the  jugular  fossa  beneath  :  it  is  perforated  in  front  by 
a  small  aperture  for  Jacobson's  nerve. 

Its  outer  watt  is  formed  mainly  by  the  membrana  tympani,  and 
by  a  ring  of  bone  which  affords  attachment  to  it;  the  latter  is 

3  Q  2 


820  TYMPANUM. 

pierced  by  the  fissura  Glaseri  (which  gives  passage  to  the  processes 
gracilis  of  the  malleus,  the  laxator  tympani,  and  the  tympanic 
branch  of  the  internal  maxillary  artery),  by  the  foramen  chordse 
posterius,  through  which  the  chorda  tympani  enters  the  tympanum, 
and  by  the  foramen  chordae  anterius,  which  is  the  commencement 
of  the  canal  of  Huguier,  for  the  exit  of  the  chorda  tympani  nerve. 

The  inner  -wall  is  vertical  and  uneven,  and  presents  the  fol- 
lowing objects,  beginning  from  above:  1.  A  horizontal  ridge, 
indicating  the  line  of  the  aqueeductus  Fallopii ;  2.  The  fenestra 
ovalis,  a  reniform  opening,  nearly  horizontal,  which  leads  into  the 
vestibule,  but  is  closed  in  the  recent  state  by  a  membrane,  to 
which  is  attached  the  base  of  the  stapes  ;  3.  Below  and  in  front  of 
the  fenestra  ovalis  is  a  convex  bony  prominence,  the  promontory ; 
it  is  occasioned  by  the  first  turn  of  the  cochlea,  and  is  marked  by 
vertical  grooves,  in  which  lie  the  branches  of  the  tympanic  plexus 
of  nerves  ;  4.  Below  and  behind  this  is  the  fenestra  rotunda,  which 
lies  at  the  bottom  of  a  conical  depression  and  is  overhung  by  a 
projection  of  bone,  so  that  it  cannot  be  seen,  except  when  viewed 
obliquely ;  it  leads  to  the  scala  tympani  of  the  cochlea,  but  is  closed 
in  the  recent  state  by  membrane ;  5.  Immediately  behind  the 
fenestra  ovalis  is  a  small  conical  eminence,  named  the  pyramid, 
in  the  summit  of  which  is  a  small  aperture,  from  which  the  tendon 
of  the  stapedius  emerges  ;  within  the  pyramid  at  its  base  is  a  small 
aperture  which  leads  to  the  aquaeductus  Fallopii,  and  transmits  a 
special  filament  from  the  facial  nerve  to  the  stapedius. 

The  posterior  wall  presents  three  or  four  openings,  one  of  them 
large,  which  lead  to  the  mastoid  cells,  and  convey  air  into  them 
from  the  tympanum.  The  mucous  membrane  of  the  tympanum  is 
continued  into  the  mastoid  cells  through  these  openings. 

The  anterior  ivall  is  pierced  by  an  aperture  for  the  transmission 
of  a  small  artery  from  the  internal  carotid.  Into  this  wall  open  the 
Eustachian  tube,  and  (in  the  dry  bone)  the  canal  for  the  tensor  tym- 
pani, which  are  separated  from  each  other  by  a  bony  septum,  the 
processus  cochleariformis.  The  Eustachian  tube  is  partly  osseous, 
partly  cartilaginous  :  the  cartilaginous  portion  has  been  described, 
p.  236  ;  the  osseous  portion,  about  half  an  inch  in  length,  opens 
into  the  lowest  part  of  the  anterior  wall,  and  is  lined  with  mucous 


MEMBRANA   TYMPANI.  821 

membrane  continuous  behind  with  that  of  the  tympanum  and  in 
front  with  that  of  the  pharynx.  The  canal  for  the  tensor  tympani 
terminates  in  the  anterior  wall  above  the  Eustachian  tube  as  a  conical 
projection,  in  the  apex  of  which  is  a  small  aperture  for  the  tensor 
muscle ;  this  projection  is  frequently  called  the  anterior  pyramid. 

Lastly,  a  nerve  called  the  chorda  tympani  (a  branch  of  the 
facial)  runs  in  an  arched  direction  from  the  back  to  the  front  of 
the  tympanum,  and  is  covered  with  mucous  membrane. 

MEMBRANA  The    membrana  tympani  is  a  thin   semi-trans- 

TYMPANI.  parent    oval    disc,    which    completely   closes   the 

bottom  of  the  meatus  auditorius  externus.  Its  transverse  diameter 
slightly  exceeds  its  vertical,  and  its  circumference  is  set  in  a  bony 
groove,  so  that  it  is  stretched,  somewhat  like  the  parchment  of  a 
drum,  on  the  outer  wall  of  the  tympanum.1  Its  plane  is  not 
vertical,  but  slants  from  above  downwards,  forming,  with  the  floor 
of  the  meatus,  an  angle  of  55°.  It  is  slightly  conical,  the  apex 
being  directed  inwards  towards  the  tympanum,  and  between  its 
layers  is  inserted  the  handle  of  the  malleus  which  runs  downwards 
and  forwards  to  a  little  below  the  centre. 

It  is  composed  of  three  layers  ;  an  outer,  formed 
by  an  extremely  thin  layer  of  true  skin  ;  an  inner, 
by  the  mucous  membrane  of  the  tympanum  ;  and  a  middle  fibrous 
layer ;  most  of  the  fibres  radiate  from  the  attachment  of  the  tip 
of  the  handle  of  the  malleus  in  a  bowed  direction,  so  that  the 
membrane  is  not  a  strict  cone  ;  other  fibres  are  annular,  forming  a 
circumferential  ring  close  to  the  osseous  ring  ;  these  stretch  over  a 
notch  in  the  upper  part  of  the  ring  (notch  of  Rivini)  so  that  the 
membrane  is  here  flaccid  and  takes  the  name  of  the  membrana 
flaccida. 

The  arteries  to  the  membrane  are  supplied  from  the  tympanic 
branch  of  the  internal  maxillary,  the  stylo-mastoid  branch  of  the 
posterior  auricular,  the  Vidian,  and  the  internal  carotid. 

OSSICULA  The  three  small  bones  in  the  tympanum    are 

AUDITUS.  named,  after  their  fancied  resemblance  to  certain 

implements,  the  malleus,  incus,  and  stapes.     They  are  articulated 

1  The  transverse  diameter  of  the  membrane  is  0-37  inch  ;  its  vertical  diameter 


822  OSSICULA   AUDITUS. 

to  each  other  by  perfect  joints,  and  are  so  placed  that  the  chain 
somewhat  resembles  the  letter  Z.     Their  use  is  to  transmit  the 
FIG.  202.  vibrations  iof  the  membrana  tympani  to  the 

membrane  of  the  fenestra  ovalis,  and,  through 
it,  to  the  fluid  contained  within  the  vestibule. 
But  they  have  another  use,  which  would  be 
incompatible  with  a  single  bone — namely,  to 
permit  the  tightening  and  relaxation  of  the 
membrane,  and  thus  adapt  it  either  to  resist 
the  impulse  of  a  very  loud  sound,  or  to 

THE  OSSICLES  OF  THE  EIGHT  » 

TYMPANUM.  favour  a  more  gentle  one. 

A.  Malleus.  B.  incus.  The  malleus  (fig.  202,  A)  or  hammer  bone, 

c.  Stapes.    It  lies  horizontally  •    ,          c  7         7        i  •    i      • 

and  forms  a  right  angle  with  consists  of  an  upper  part  or  head,  which  is 
the  long  process  of  the  incus.  SUSpended  from  the  roof  of  the  tympanum  by 
the  suspensory  ligament,  and  articulates  posteriorly  with  the  incus. 
Below  the  head  is  a  narrow  constriction,  the  neck,  which  is  con- 
tinued on  into  a  long,  somewhat  curved,  tapering  process,  the 
manubrium  or  handle :  it  is  nearly  vertical,  and  is  attached  along 
its  whole  length  to  the  upper  half  of  the  membrana  tympani, 
passing  between  its  inner  and  middle  layers.  The  processiis  gracilis 
projects  at  a  right  angle  below  the  neck,  runs  into  the  Glaserian 
fissure,  and  receives  the  insertion  of  the  laxator  tympani.  The 
processus  brevis  is  a  stunted  projection,  situated  at  the  junction  of 
the  processus  gracilis  and  manubrium,  and  touches  the  membrana 
tympani ;  it  receives  the  insertion  of  the  tensor  tympani. 

The  incus,  or  anvil  bone  (fig.  202,  B),  is  shaped  like  a  tooth,  with 
two  unequal  widely  separated  fangs.  Its  broad  part  or  body  pre- 
sents a  concavo-convex  articulation  in  front  for  the  head  of  the 
malleus ;  its  long  process  runs  nearly  parallel  with  the  handle  of  the 
malleus,  and  articulates  with  the  stapes  through  the  intervention  of 
a  small  bone,  the  os  orbiculare,  which,  in  adult  life,  forms  part  of 
the  long  process,  but  in  foetal  life  is  a  separate  bone ;  its  short 
process  is  directed  horizontally  backwards,  and  its  point  is  fixed  in 
a  small  hollow  at  the  commencement  of  the  mastoid  cells. 

The  stapes,  or  stirrup  bone  (fig.  202,  c),  lies  horizontally.  Its 
head  articulates  with  the  long  process  of  the  incus.  Below  the 
head  is  a  constriction,  the  neck,  which  receives  at  its  posterior  part 


MUSCLES   OF   THE   TYMPANUM.  823 

the  insertion  of  the  stapedius.  Two  diverging  cntra  pass  from  the 
head  to  an  oval  plate  of  bone,  the  base,  which  is  attached  to  the 
membrane  covering  the  fenestra  ovalis. 

The  tympanic  bones  are  maintained  in  their  positions  by 
various  ligaments.  The  anterior  ligament  of  the  malleus  passes 
from  the  head  of  this  bone  to  the  anterior  wall  of  the  tympanum  ; 
the  suspensory  ligament  descends  from  the  roof  of  the  tympanum 
outwards  to  the  head  of  the  malleus,  and  the  posterior  ligament 
of  the  incus  passes  from  the  short  process  to  the  posterior  wall  near 
the  mastoid  cells.  The  ossicles  are  connected  by  an  imperfect 
capsular  ligament,  which  passes  from  the  long  process  of  the 
incus  to  the  head  of  the  stapes;  and  by  another  which  passes 
from  the  head  of  the  malleus  to  the  incus.  The  base  of  the  stapes 
is  attached  to  the  margin  of  the  fenestra  ovalis  by  an  annular 
ligament.  The  surfaces  of  the  bones  forming  these  two  little 
joints  are  covered  with  cartilage.  The  joints  have  also  synovial 
membranes. 

MUSCLES  OF  The  muscles,  by  moving  the  tympanic  bones, 

THE  TYMPANUM.         tighten  or  relax  the  membrana  tympani. 

The  tensor  tympani  runs  in  a  canal  above  and  parallel  to  the 
Eustachian  tube,  from  the  cartilaginous  part  of  which  it  arises, 
as  well  as  from  the  apex  of  the  petrous  portion  of  the  temporal 
bone.  It  passes  backwards,  and  terminates  in  a  round  tendon, 
which  enters  the  front  wall  of  the  tympanum  through  a  special 
bony  canal,  and,  making  a  sharp  bend  outwards,  is  inserted  into 
the  root  of  the  handle  of  the  malleus.  Its  nerve  comes  from  the 
otic  ganglion.  Its  action  is  to  draw  inwards  the  head  of  the 
malleus,  and  thus  render  the  membrane  tense. 

The  laxator  tympani  arises  from  the  spinous  process  of  the 
sphenoid,  and  the  cartilaginous  portion  of  the  Eustachian  tube,  and 
is  inserted  into  the  neck  of  the  malleus  close  to  the  root  of  the 
processus  gracilis.  It  is  supplied  by  a  branch  of  the  facial  nerve.1 
Its  action  is  to  relax  the  membrana  tympani. 

The  stapedius  arises  from  the  hollow  of  the  pyramid,  and  its 

1  This  is  usually  regarded  as  a  muscle,  and  is  described  here  as  such  ;  no  mus- 
cular fibres,  however,  can  be  traced  in  it,  so  that  it  is  probably  only  ligamentous  in 
structure — a  fact  borne  out  in  the  lower  animals. 


824  TYMPANUM. 

tendon,  emerging  through  the  aperture  in  the  apex,  runs  forwards 
to  be  inserted  into  the  neck  of  the  stapes.1  Its  nerve  is  derived 
from  the  facial.  By  its  action  it  increases  the  tension  upon  the 
fluid  in  the  vestibule. 

The  mucous  membrane  of  the  tympanum  is  continuous  with  that 
of  the  pharynx.  It  covers  the  ossicles,  muscles,  and  nerves,  and  is 
prolonged  into  the  mastoid  cells.  The  membrane  is  pale  and  thin, 
and  lined  with  columnar  ciliated  epithelium,  except  on  the  pro- 
montory, the  membrana  tympani,  and  the  ossicles,  where  there  is 
only  a  single  layer  of  flattened  cells. 

A  branch  (chorda  tympani)  of  the  facial  nerve  enters  the  tym- 
panum through  a  foramen,  foramen  chordce  posterius,  at  the  base  of 
the  pyramid ;  it  then  crosses  the  tympanum  beneath  the  handle  of 
the  malleus  and  the  long  process  of  the  incus,  leaves  the  tympanum 
through  a  foramen,  foramen  chordce  anterius,  and  then  traverses  a 
canal  (canal  of  Huguier),  which  runs  close  to  the  Glaserian  fissure. 
It  eventually  joins  the  submaxillary  ganglion  (p.  141). 

The  arteries  supplying  the  tympanum  are :  (1)  the  tympanic 
branch  of  the  internal  maxillary,  which  enters  through  the  fissura 
Glaseri ;  (2)  the  stylo-mastoid  branch  of  the  posterior  auricular  ; 
(3)  small  branches  from  the  ascending  pharyngeal,  which  enter 
with  the  Eustachian  tube  ;  (4)  branches  from  the  interna  Icarotid 
artery ;  and  (5)  the  petrosal  branch  of  the  arteria  meningea  media. 

The  veins  open  into  the  middle  meningeal  and  the  pharyngeal 
veins. 

The  mucous  membrane  is  supplied  with  branches  from  the 
tympanic  plexus,  which  is  formed  by  filaments  from  the  tympanic 
branch  of  the  glosso-pharyngeal  nerve,  from  the  carotid  sympathetic 
plexus,  and  from  the  large  and  small  superficial  petrosal  nerves. 

This,  in  consequence  of  its  complexity,  is  called 

INTEBNAL  EAB.          .        ,          .  *  .  „          .  .  , 

the   labyrinth.     It  consists  or   cavities  excavated 

in  the  most  compact  part  of  the  temporal  bone,  and  it  is  divided 
into  three  parts  :  a  middle  one,  called  the  vestibule,  being  the 
common  cavity  in  which  all  communicate ;  an  anterior,  named, 
from  its  resemblance  to  a  snail's  shell,  the  cochlea ;  and  a  posterior, 

1  There  is  a  little  sheath,  lined  with  synovial  membrane,  to  facilitate  the  play 
of  the  tendon  in  the  pyramid. 


VESTIBULE. 


825 


consisting  of  three  semicircular  canals  ;  it  communicates  externally 
with  the  tympanum  by  means  of  the  fenestra  ovalis  and  rotunda, 
and  internally  with  the  meatus  auditorius  internus.  These  cavities 
are  filled  with  a  clear  fluid,  called  the  endolymph,  and  contain  a 
membranous  expansion,  the  membranous  labyrinth,  upon  which  the 
filaments  of  the  auditory  nerve  are  expanded. 

The  vestibule,  or  central  chamber,  is  an  irregular 
oblong  cavity,  about  one-fifth  of  an  inch  in  its 
widest  part,  which  is  at  its  antero-posterior  and  at  its  vertical 
diameters.  On  its  outer  wall  is  the  fenestra  ovalis,  which  is  closed 
in  the  recent  state  by  the  base  of  the  stapes  ;  on  its  inner  wall,  at 

FIG.  203. 


VESTIBULE. 


1.  The    superior   semicir- 

cular canaL 

2.  The   posterior  semicir- 

cular canal. 

3.  The    external    semicir- 

cular canal. 

4.  Common  opening  of  the 

superior  and  posterior 
semicircular  canals. 


5.  Aquasductus  vestibuli. 

6.  Aquwductus  cochleae. 

7.  Fovea  hemi-elliptica. 

8.  Fovea  hemispherica. 

9.  Scala  tympani. 
1 0.  Scala  vestibuli. 


OSSEOUS   LABYKINTH    OF    THE    EIGHT    SIDE    (S6mmering). 
(Two  and  a  half  times  its  natural  size.) 

the  front  part,  is  a  shallow  round  depression,  the  fovea  hemispherica, 
which  is  perforated  at  its  lower  by  numerous  foramina,  macula 
cribrosa,  for  the  transmission  of  the  filaments  of  the  auditory  nerve. 
Posteriorly,  this  pit  is  bounded  by  a  ridge,  the  crista  vestibuli,  and 
in  some  subjects  there  is  behind  this  eminence  the  opening  of  a 
small  canal,  called  the  aquceductus  vestibuli.  It  leads  to  the  pos- 
terior surface  of  the  pars  petrosa,  and  transmits  a  small  vein.  In 
the  roof  is  a  transverse  oval  depression,  the  fovea  hemi-elliptica, 
which  lodges  the  utricle ;  posteriorly,  the  five  openings  of  the  semi- 
circular canals  open  into  it ;  and,  in  front,  is  a  large  opening  through 
which  it  communicates  with  the  scala  vestibuli  of  the  cochlea. 


826  SEMICIRCULAR   CANALS. 

SEMICIECULAB  The  semicircular  canals,  three  bony  canals,  are 

CANALS.  situated  above  and  rather  behind  the  vestibule. 

Each  canal  forms  about  two-thirds  of  a  circle,  is  compressed 
laterally,  and  is  about  -^th  of  an  inch  in  diameter.  The  canals 
are  not  of  equal  diameter  throughout ;  each  presents  at  one  end 
a  dilatation  termed  the  ampulla,  about  -j^th  of  an  inch  in  diameter. 
This  dilatation  corresponds  to  a  similar  dilatation  of  the  mem- 
branous sac,  upon  which  the  auditory  nerve  expands.  The  canals 
open  at  each  extremity  into  the  vestibule  by  five  openings,  since 
one  of  the  apertures  is  common  to  the  extremities  of  two  canals. 
Each  canal  differs  in  its  direction  ;  they  are  named  accordingly 
superior,  posterior,  and  external. 

The  superior  semicircular  canal  (fig.  203,  i)  is  the  most  anterior 
of  the  three  ;  its  direction  is  vertical,  and  runs  across  the  petrous 
bone.  It  rises  up  higher  than  any  other  portion  of  the  labyrinth, 
and  its  ampulla  is  at  the  outer  and  anterior  extremity,  and  opens 
into  the  upper  part  of  the  vestibule  ;  its  non-ampullated  extremity 
opens  by  a  common  orifice  with  the  posterior  semicircular  canal 
into  the  back  part  of  the  vestibule. 

The  posterior  semicircular  canal  (fig.  203,  2)  is  also  vertical,  and 
runs  parallel  to  the  posterior  surface  of  the  petrous  bone,  conse- 
quently at  right  angles  to  the  preceding.  It  is  the  longest  of  the 
three  canals,  and  its  ampullated  extremity  is  at  the  lower  end, 
opening  into  the  lower  and  back  part  of  the  vestibule.  Its  upper 
non-dilated'  end  joins  with  that  of  the  superior  semicircular  canal. 

The  external  semicircular  canal  (fig.  203,  3),  the  shortest  of  the 
three,  is  horizontal  in  position,  with  the  convexity  of  the  arch 
diverted  backwards  ;  it  opens  by  its  extremities  directly  into  the 
back  of  the  vestibule ;  the  ampulla  is  at  the  outer  end  and  opens 
into  the  vestibule  just  above  the  fenestra  ovalis. 

The  cochlea  is  the  most  anterior  part  of  the 
COCHLEA.  . 

osseous  labyrinth ;  it  very  closely  resembles  a 
common  snail's  shell,  and  is  placed  nearly  horizontally,  so  that  its 
first  coil  is  directed  forwards  and  outwards,  and  corresponds  with 
the  promontory ;  while  its  base  corresponds  to  the  bottom  of  the 
meatus^  auditorius  internus,  and  is  perforated  by  apertures  for  the 
transmission  of  the  cochlear  branches  of  the  auditory  nerve.  The 


COCHLEA.  827 

diameter  of  its  base,  and  also  of  its  height,  is  about  the  same, 
namely,  a  quarter  of  an  inch.  It  consists  of  a  gradually  tapering 
spiral  tube,  which  winds  round  a  central  pillar,  called  the  modiolus 
or  colnmella.  The  spiral  canal  is  divided  into  two  parallel  tubes, 
scalce,  by  a  delicate  lamina,  partly  bony,  partly  membranous,  which 
is  called  the  lamina  spiralis.  In  the  dry  condition  this  parti- 
tion is  only  partial ;  but  in  the  recent  state  it  is  completed  by  a 
membrane. 

The  spiral  canal  (fig.  203,  9,  10)  is  about  an  inch  and  a  half 
long,  and  about  the  -j^th  of  an  inch  in  diameter,  lessening  as  it 
approaches  the  summit.  After  making  two  turns  and  a  half,  it 
terminates  at  the  apex  of  the  cochlea  in  a  rounded  dome — the 
cupola.  The  coil  at  the  base  is  the  widest,  the  second  being  a 

FIG.  204. 


1.  Scala  tympani.  3.  Lamina  spiralis 

2.  Scala  vestibuli.          ^^^^A  Br~*  ossen< 

4.  Modiolus,  or  central 

pillar. 

£J^^^ 

THE    OSSEOUS    COCHLEA.       (MAGNIFIED    FIVE    TIMES.) 

very  small  one.  The  canal  has  in  it  three  openings;  thus  it 
communicates  with  the  vestibule  by  an  oval  opening;  with  the 
tympanum  by  the  fenestra  rotunda,  but  which  in  the  recent  state 
is  closed  by  the  membrana  secundaria ;  and,  lastly,  there  is  the 
aperture  of  the  aquceductus  cochlece,  which  transmits  a  small  vein 
from  the  cochlea  to  the  internal  jugular  vein. 

The  modiolus  or  columella  (fig.  204,  4)  is  the  central  pillar  of 
the  cochlea  around  which  the  spiral  canal  coils,  and  it  passes  from 
the  base  to  the  apex.  It  is  of  considerable  thickness  at  its  base, 
but  gradually  tapers  towards  the  apex,  where  at  the  last  half  coil 
it  terminates  in  a  half  funnel-shaped  curved  lamella,  called  the 
infundibulum.  Here  the  partition  disappears,  and  is  called  the 
helicotrema,  so  that  the  scalge  vestibuli  and  cochleae  communicate 
with  each  other  in  this  situation.  The  interior  of  the  modiolus  is 


828  COCHLEA. 

composed  of  cancellous  bone,  and  is  traversed  by  numerous  canals, 
which  transmit  small  vessels  and  nerves  to  the  lamina  spiralis. 
One  of  these  canals,  larger  than  the  others,  runs  up  the  centre 
of  the  modiolus  nearly  to  the  apex,  and  transmits  a  small  artery, 
the  arteria  centralis  modioli. 

On  making  a  vertical  section  through  the  cochlea,  we  observe 
that  the  spiral  canal  is  divided  into  three  tubes,  termed  scalce ;  the 
lower  and  largest  is  the  scala  tympani  (fig.  205,  s  T)  ;  the  upper  is 
the  scala  vestibuli  (fig.  205,  sv),  which  is  subdivided  by  an  oblique 
membrane  to  form  an  outer  or  third  tube — the  scala  media  or  canalis 
cochlece  (fig.  205,  D  c). 

TheZamma  spiralis  (fig.  204,  3)  is  the  projecting  partition  which 
divides  the  spiral  canal  into  two  tubes  or  scalse  :  is  composed  on  the 
inner  half,  of  bone — lamina  spiralis  ossea — and  on  the  outer  half  of 
membrane — membrana  basilaris.  The  lamina  spiralis  ossea  ends  at 
the  cupola  in  a  hook-like  process — the  Jiamulus.  Winding  round 
the  modiolus,  close  to  the  attachment  of  the  lamina  spiralis  ossea, 
is  a  small  canal — the  canalis  spiralis  modioli— which  is  filled  by  the 
gangliform  swelling  of  the  cochlear  nerve,  called  the  ganglion  spirale. 
The  osseous  lamina  spiralis  is  seen,  on  a  vertical  section,  to  be  com- 
posed of  two  plates,  between  which  the  structure  is  spongy,  and 
presents  a  number  of  small  canals  for  the  passage  of  the  small  fila- 
ments of  the  cochlear  division  of  the  auditory  nerve,  in  their  course 
to  the  membranous  part  of  the  lamina. 

On  examining  the  membranous  continuation  of  the  lamina 
spiralis,  it  is  seen,  not  far  from  its  attachment  to  the  osseous  zone, 
to  be  thickened  into  an  elongated  crest — the  limbus  lamince  spiralis 
(fig.  205,  1 1  s) — which  overhangs  a  groove,  called  the  sulcus  spiralis 
(fig.  205,  s  s)  ;  the  upper  horn  of  the  groove  is  called  the  labium 
vestibulare ;  the  lower,  the  labium  tympanicwn.  From  the  labium 
tympanicum,  the  basilar  membrane  is  continued  outwards  to  be 
attached  to  the  outer  wall  of  the  canal,  and  thus  completes  the 
septum.  At  the  point  of  attachment  of  the  basilar  membrane  with 
the  outer  wall  of  the  cochlea  -may  be  seen  a  triangular  projection, 
which,  formerly  described  as  a  muscle  (coclilearis  muscle),  is  now 
recognised  to  be  a  collection  of  connective-tissue  cells,  and  called 
the  ligamentum  spirale  (fig.  205, 1  sp).  The  structure  of  the  limbus 


COCHLEA.  829 

consists  of  firm  connective  tissue,  on  the  under  part  of  which  are 
found  numerous  cells.  Close  to  the  junction  of  the  limbus  with  the 
basilar  membrane  are  a  series  of  regularly  arranged  apertures,  look- 
ing upwards  to  the  sulcus  spiralis  :  these  are  oVoid  apertures  for  the 
exit  of  branches  of  the  cochlear  nerve. 

The  basilar  membrane  forms,  at  the  base  of  the  cochlea,  but  a 
small  breadth  of  the  septum,  the  broadest  part  being  composed  of 
bone  ;  but  it  gradually  increases  in  breadth  towards  the  cupola, 
where  it  constitutes  nearly  the  entire  septum.  It  consists  of  a, 

FIG.  205. 


DIAGRAMMATIC    SECTION    OF   A   COIL   OF    THE    COCHLEA.       (From  Quaill.) 

8  v.  Scala  vestibuli.  r  c.  Rods  of  Corti. 

D  c.  Ductus  coclilearis.  m  6.  Membrana  basilaris. 

s  T.  Scala  tympani.  I  s  p.  Ligamentum  spirals. 

m  is.  Membrane  of  Reissner.  s  s.  Sulcus  spiralis. 

1 1  s.  Limbus  laminse  spiralis.  g  s.  Ganglion  spirale. 

m  T.  Membrana  tectoria. 

firm,  fibrillated  tissue,  which  is  probably  formed,  at  any  rate  on 
its  upper  surface,  of  a  structure  closely  resembling  the  organ  of 
Corti. 

It  has  been  stated  that  in  the  bony  cochlea  there  is  a  partial 
septum  dividing  the  spiral  tube  into  two  incomplete  scalas.  In 
the  recent  condition  the  basilar  membrane  completes  the  septum 
dividing  the  upper  tube  into  an  upper  canal — the  scala  vestibuli, 
and  a  lower,  the  scala  tympani.  The  upper  scala  is  subdivided  by 
an  oblique  membrane,  membrane  of  Reissner,  into  two  canals — an 


830  COCHLEA. 

inner,  the  scala  vestibuli,  and  an  outer,  the  canalis  cochlece,  the  scala 
media  or  the  ductus  cochlearis  (fig.  205,  D  c).  The  canalis  cochleae 
terminates  at  the  helicotrema  in  a  cul-de-sac  ;  inferiorly,  it  is  con- 
nected with  the  saccule  by  a  long  narrow  duct,  called  the  canalis 
reuniens. 

The  membrane  of  Reissner  (fig.  205,  M  R),  is  the  oblique  mem- 
brane which  separates  the  scala  vestibuli  and  the  canalis  cochleas. 
It  is  a  delicate,  almost  structureless,  layer,  composed  of  connective 
tissue,  continuous  with  the  periosteum  lining  the  upper  surface  of 
the  lamina  spiralis.  It  is  smooth  on  its  vestibular  surface,  and  is 
lined  with  flattened  connective-tissue  cells ;  on  its  cochlear  surface 
it  is  covered  with  squamous  epithelium. 

The  inner  wall  of  the  canalis  cochlese  is  formed  by  the  mem- 
brane of  Keissner  covered  with  pavement  epithelium.  The  outer 
wall,  the  periosteum,  is  thickened  by  a  quantity  of  retiform  con- 
nective tissue  lined  with  columnar  epithelial  cells.  An  increase 
of  this  tissue  is  seen  a  little  above  the  ligamentum  spirale  as  a 
conical  eminence,  in  which  runs  a  small  vessel,  the  vas  spirale; 
midway  between  the  vas  and  the  attachment  of  Reissner's  mem- 
brane is  another  thickening,  consisting  also  of  numerous  blood- 
vessels, stria  vascularis,  which  form  anastomosing  loops.  The 
lower  wall  is  formed  by  the  limbus  spiralis  and  the  basilar  mem- 
brane ;  upon  the  latter  is  placed  the  complex  structure,  called  the 
organ  of  Corti. 

The  organ  of  Corti,  placed  upon  the  upper  surface  of  the  mem- 
brana  basilaris,  presents  a  slight  triangular  elevation  outside  the 
limbus,  and  winds  spirally  throughout  the  cochlea,  from  its  base  to 
its  summit.  The  central  part  of  the  organ  (fig.  206,  T  c)  consists 
of  two  sets,  an  inner  and  an  outer,  of  slanting  rods — rods  of  Corti 
— which  rest  against  each  other  at  their  upper  extremities,  thus 
forming  a  triangular  tunnel,  called  the  unnel  of  Corti,  filled  in  the 
recent  state  with  endolymph.  The  inner  and  the  outer  rods  are 
similar  in  structure,  but  differ  in  shape — the  inner  are  shorter,  less 
oblique,  and  have  the  shape  of  the  human  ulna,  the  outer  resemble 
a  swan's  head,  the  head  being  received  into  the  concavity  of  the 
inner  rod,  the  part  resembling  the  bill  looking  horizontally 
outwards.  Both  have  a  broad  nucleated  base,  and  present  a 


COCHLEA. 


831 


fibrillar  appearance.     The  inner  rods  are  more  numerous  than  the 
outer.1 

On  the  inner  side  of  the  inner  rods  is  a  single  row  of  broad 
epithelial  cells  tipped  with  stiff  ciliated  processes,  called  the  inner 
hair  cells ;  and  on  the  outer  side  of  the  outer  rods,  resting  on  cells 
which  are  placed  on  the  basilar  membrane,  are  four  to  six  rows  of 

FIG.  200. 


VERTICAL    SECTION    OF    THE    FIRST     TURN    OF    THE    COCHLEA,    SHOWING    THE    MEMBRANOUS 
COCHLEA   AND  THE    POSITION  OF    THE  ORGAN    OF    CORTI.     (AFTER  WALDEYER   AND    QUIN.) 

similar  cells,  termed  the  outer  hair  cells  (206,  o  c).  The  bases  of 
the  outer  hair  cells  present  on  one  side  a  rounded  bulge,  while  from 
the  other  are  long  processes  which  pass  downwards  to  be  attached 

1  According  to  Waldeyer,  in  the  proportion  of  6,000  of  the  inner  to  4,500  of  the 
outer  rods. 


832  MEMBRANOUS    LABYRINTH. 

to  the  membrana  basilaris.  The  outer  rods  are  placed  upon  nume- 
rous fusiform  nucleated  cells,  cells  of  Deiters,  whose  bases  rest  upon 
the  basilar  membrane,  and  whose  summits  taper  off  into  fine  long 
cubicular  processes,  phalangeal,  which  pass  between  the  outer  hair 
cells  to  be  connected  to  the  phalanges  of  the  reticular  lamina. 

The  lamina  reticularis  is  the  net-like  membrane  surmounting 
the  summits  of  the  outer  hair  cells.  It  is  an  open  network,  of  a 
fiddle-shape  pattern,  consisting  of  four  rows  of  fiddle-shaped  cells 
termed  phalanges,  through  which  the  ciliated  processes  of  the  hair 
cells  project.  To  these  phalanges,  as  before  stated,  are  attached 
the  phalangeal  processes  of  the  cells  of  Deiters. 

The  tectorial  membrane  (fig.  205,  M  T)  is  the  only  remaining 
membrane  to  be  described,  and  lies  above  and  parallel  to  the  basilar 
membrane,  but  does  not  extend  more  than  half-way  over  it.  It  is 
connected  on  its  inner  side -with  the  limbus  spiralis,  and  is  then 
continued  outwards,  overlying  and  resting  upon  the  rods  of  Corti ; 
at  its  origin  it  is  thin,  subsequently  it  thickens,  and  then  gradually 
tapers  off  to  end  in  a  free  extremity.  It  is  a  strong,  elastic  mem- 
brane, distinctly  fibrous,  especially  upon  its  inner  and  thicker  part. 
MEMBRANOUS  If  the  bony  labyrinth  just  described  be  properly 

LABYRINTH.  understood,  there  will  not  be  much  difficulty  in 

comprehending  the  shape  of  the  membranous  labyrinth  in  its  in- 
terior— a  structure  supporting  the  ultimate  ramifications  of  the 
auditory  nerve.  It  has  the  general  form  and  shape  of  the  vestibule 
and  the  semicircular  canals,  although  smaller,  and  it  is  separated 
from  the  osseous  labyrinth  by  a  quantity  of  fluid  called  peri- 
lymph  or  liquor  Cotunnii,  which  is  secreted  by  the  delicate  serous 
membrane  lying  in  the  bony  labyrinth. 

The  membranous  labyrinth  is  a  sac,  contained  partly  in  the 
vestibule  and  partly  in  the  semicircular  canals  :  that  situated  in 
the  vestibule  is  termed  the  vestibular  portion;  that  in  the  bony 
canals,  the  membranous  semicircular  canals. 

The  sac  in  the  vestibule  is  so  constructed  as  to  form  two  sacs 
of  unequal  size,  which  indirectly  communicate  with  each  other.1 

1  From  the  utricle  there  proceeds  a  small  canal,  which  lies  in  the  aqu^ductus 
vestibuli ;  this  is  joined  close  to  its  commencement  by  a  similar  canal  from  the 
saccule  ;  thus  forming  the  indirect  communication  above  alluded  to. 


MEMBRANOUS   LABYRINTH.  833 

The  utricle  or  common  sinus,  the  larger  of  the  two,  is  oval  and 
compressed  laterally,  and  communicates  with  the  five  openings  of 
the  membranous  semicircular  canals.  It  is  lodged  in  the  fovea 
hemi-elliptica,  and  its  wall  is  thickest  (macula  acustica)  close  to 
the  crista  vestibuli,  where  the  branches  from  the  auditory  nerve  enter 
it.  The  saccule,  the  smaller,  is  globular  and  flattened,  and  lies 
in  the  fovea  hemispherica,  in  front  of  the  utricle.  It  is  connected 
with  the  membranous  canal  of  the  cochlea  by  a  small  short  duct, 
termed  the  canalis  reuniens.  From  the  saccule  there  passes  down- 
wards, along  the  aquaeductus  vestibuli,  a  narrow  prolongation, 
which  terminates  in  a  pyriform  dilatation,  saccus  endolymphaticus ; 
this  canal  is  joined,  at  an  acute  angle,  by  a  short  narrow  canal 
from  the  front  of  the  utricle,  so  that  there  is  a  communica- 
tion existing  throughout  the  entire  length  of  the  membranous 
labyrinth. 

The  utricle  and  the  saccule  contain  on  their  inner  wall  a  minute 
mass  of  calcareous  matter  in  connection  with  nerve-ends,  called  by 
Breschet  the  otoliths  or  otoconia.  They  are  crystals  of  carbonate  of 
lime,  and  are  present  in  the  labyrinth  of  all  mammalia.  From 
their  greater  hardness  and  size  in  aquatic  animals,  there  is  reason 
to  believe  that  they  perform  the  office  of  rendering  the  vibrations 
of  sound  sharper  and  more  distinct.1 

MEMBRANOUS  ^h°  membranous   semicircular   canals   present 

SEMICIRCULAR  the  same  dilatations  or  ampullae  as  the  bony  ones 

CANALS.  at  one  gj^  and  at  this  part  they  nearly  fill  their 

bony  cases ;  but  in  the  rest  of  their  extent  the  diameter  of  the 
membranous  canal  is  not  more  than  one-third  to  one-fifth  that  of 
the  bony.  At  the  ampullated  extremity  the  sac  is  connected  on 
its  outer  aspect  by  blood-vessels  and  nerves  to  the  periosteum, 
forming  on  section  a  transverse  projection,  called  the  septum 
transversum  or  crista  acustica,  which  forms  a  partial  septum. 

The  membranous  semicircular  canals  consist  of  three  layers,  an 

1  For  a  detailed  description  of  the  relation  of  the  otoliths  with  the  hair-like 
processes  of  the  nerve-filaments,  the  student  is  referred  to  an  article  by  Dr.  Urban 
Pritchard  in  the  Quarterly  Journal  of  Microscopic  Science,  October  1876,  entitled 
'  The  Termination  of  the  Nerves  in  the  Vestibule,  and  Semicircular  Canals  of 
Mammals.' 

3  H 


834  AUDITORY   NERVE. 

outer  or  fibrous  layer,  which  is  connected  with  the  periosteum  by 
blood-vessels,  and  contains  irregular  pigment-cells;  a  middle  or 
tunica  propria,  clear  and  structureless ;  and  an  inner  or  epithelial 
layer,  which  lines  the  inner  space  of  the  tunica  propria.  At 
the  ampullae  the  epithelial  layer  is  composed  of  the  columnar 
variety,  upon  which  are  arranged  cells  of  a  spindle  shape,  having 
delicate  ciliated  processes  (auditory  hairs)  projecting  into  the 
endolymph. 

The  membranous  labyrinth  is  protected,  inside  and  out,  by 
fluid.  The  fluid  in  the  interior  is  termed  the  endolymph  or  liquor 
Scarpce,  and  the  thin  layer  between  it  and  the  bone,  the  perilymph 
or  liquor  Cotunnii ;  thus  the  delicate  nervous  membrane  is  placed 
between  two  layers  of  fluid. 

DISTRIBUTION  The  auditory  nerve,  or  the  eighth  cranial  nerve, 

OF  THE  AUDITOKY  passes  down  the  meatus  auditorius  internus,  and, 
NEKVE-  at  the  bottom  of  it,  divides  into  an  anterior  and 

posterior  branch,  which,  after  breaking  up  into  numerous  fasciculi, 
are  distributed  to  the  cochlea  and  to  the  vestibule. 

The  vestibular  nerve  divides  into  five  branches,  which  proceed 
to  the  utricle,  the  saccule,  and  the  three  ampullae  of  the  semi- 
circular canals,  respectively :  those  for  the  utricle,  and  the  superior 
and  external  semicircular  canals  enter  the  vestibule  along  the  crista 
vestibuli ;  that  for  the  saccule  enters  through  the  fovea  hemi- 
spherica,  and  that  for  the  posterior  semicircular  canal  is  continued 
along  a  bony  canal  to  its  termination.  The  nerves  to  the  semi- 
circular canals  enter  the  ampullae  by  a  forked  swelling  which 
corresponds  to  each  septum  transversum. 

The  cochlear  division  of  the  auditory  nerve  is  a  short,  thick 
branch,  which  breaks  up  into  numerous  filaments  at  the  bottom  of  the 
meatus  auditorius  internus.  These  enter  the  canals  in  the  base  of 
the  modiolus,  and  then  arch  outwards  between  the  plates  of  the 
lamina  ossea.  In  their  course  outwards  between  the  plates,  they 
pass  through  the  spirally  arranged  ganglionic  cord,  ganglion  spirale, 
beyond  which  they  form  a  wide  plexus.  They  are  collected  to- 
gether close  to  the  free  border  of  the  osseous  zone,  forming  a  very 
minute  nerve-plexus,  whose  filaments  interlace  freely ;  they  then 


AUDITORY   NERVE.  835 

enter  the  membranous  zone  to  be  connected  with  the  inner  hair-cells 
of  the  organ  of  Corti.1 

The  vessels  which  supply  the  cochlea  are  from  ten  to  twelve  in 
number,  and  are  derived  from  the  auditory  artery ;  they,  like  the 
nerves,  enter  the  bony  canals  of  the  modiolus,  and  then  turn  out- 
wards to  ramify  upon  the  osseous  zone,  supplying  its  periosteum. 
The  plexus  formed  by  these  branches  communicates  with  a  vessel 
known  as  the  vas  spirale,  which  runs  longitudinally  in  the  liga- 
mentum  spirale  to  the  outer  attachment  of  the  membrana  basilaris. 
The  veins  from  the  cochlea  terminate  in  the  superior  petrosal  sinus, 
having  previously  joined  those  of  the  vestibule  and  semicircular 

canals. 

i 

1  Some  anatomists  describe  filaments  as  passing  between  the  rods  of  Corti  to 
end  in  the  outer  hair-cells. 


3  H  2 


DISSECTION  OF   THE  MAMMARY  GLAND. 

THE  form,  size,  position,  and  other  external  characters  of  the 
mammary  gland  in  the  female  vary  more  or  less  in  different  persons. 
The  longest  diameter  of  the  gland  is  in  a  direction  upwards  and 
outwards  towards  the  axilla ;  its  thickest  part  is  at  the  centre,  and 
the  fulness  and  roundness  of  the  gland  depend  upon  the  amount  of 
fat  about  it.  Its  deep  surface  is  flattened  in  adaptation  to  the 
pectoral  muscle,  to  which  it  is  firmly  connected  by  an  abundance 
of  areolar  tissue.  In  its  vertical  direction  the  breast  corresponds 
to  the  space  between  the  third  and  sixth  or  seventh  ribs ;  in  its 
lateral  direction,  to  the  space  between  the  side  of  the  sternum  and 
the  axilla,  while  the  nipple  corresponds  to  the  fourth  rib,  or  a 
little  below  it. 

It  is  enclosed  by  a  fascia,  which  not  only  supports  it  as  a  whole, 
but  penetrates  into  its  interior,  so  as  to  form  a  framework  for  its 
several  lobes  ;  hence  it  is  that,  in  cases  of  mammary  abscess,  the 
matter  is  apt  to  be  circumscribed,  not  diffused. 

The  nipple  (mammilla)  projects  a  little  below  the  centre;  it  is 
surrounded  by  a  coloured  circle,  termed  the  areola ;  this  circle  is  of 
a  rose-pink  colour  in  virgins,  but  in  those  who  have  borne  children 
of  a  dark  brown.  It  begins  to  enlarge  and  grow  darker  about  the 
second  or  third  month  of  pregnancy,  and  these  changes  continue 
till  parturition.  The  areola  is  abundantly  provided  with  papilte, 
and  with  subcutaneous  sebaceous  glands,  to  lubricate  the  surface 
during  lactation ;  the  areola  as  well  as  the  nipple  is  destitute  of 
fat. 

The  gland  itself  consists  of  distinct  lobes  held 

together  by  firm  connective  tissue,  and  provided 

with  separate  lactiferous  ducts.     Each  lobe  divides  and  subdivides 


THE   MAMMARY   GLAND.  837 

into  lobules,  and  the  duct  branches  out  accordingly.1  Traced  to 
their  origin,  we  find  that  the  ducts  commence  in  clusters  of  minute 
cells,  and  that  the  blood-vessels  ramify  minutely  upon  these  cells ; 
altogether,  then,  a  single  lobe  might  be  compared  to  a  bunch  of 
grapes,  of  which  the  stalk  represents  the  main  duct.  The  main 
ducts  (galactophorous  ducts)  from  the  several  lobes,  from  fifteen  to 
twenty  in  number,  converge  towards  the  nipple,  and,  just  before 
they  reach  it,  become  dilated  into  small  sacs  or  ampullce,  two  or 
three  lines  wide  ;  after  this  they  run  up  to  the  apex  of  the  nipple, 
and,  running  parallel,  terminate  in  separate  orifices. 

The  vesicles  and  the  galactophorous  ducts  are  lined  with 
columnar  epithelium,  except  at  their  orifices,  where  it  becomes 
squamous. 

The  arteries  of  the  gland  are  derived  from  the  long  thoracic,  the 
internal  mammary,  and  the  intercostals ;  the  nerves  come  from  the 
anterior  and  lateral  cutaneous  branches  of  the  intercostal  nerves, 
and  from  the  descending  branches  of  the  cervical  plexus.  The 
veins  diverge  from  the  nipple,  and  terminate  in  the  axillary  and 
internal  mammary  veins. 

The  lymphatics  run  chiefly  to  the  axillary  glands,  but  some 
pierce  the  front  of  the  intercostal  spaces  to  join  the  anterior 
mediastinal  glands. 

1  It  is  observed,  in  some  cases,  that  one  or  more  lobules  run  off  to  a  consider- 
able distance  from  the  main  body  of  the  gland,  and  lie  embedded  in  the  subcu- 
taneous tissue.  This  should  be  remembered  when  it  is  necessary  to  remove  the 
entire  gland. 


838 


DISSECTION  OF  THE  SCROTUM  AND   TESTIS. 

THE  scrotum  is  a  pouch  of  skin  for  the  lodgment  of  the  two  testes. 
They  are  originally  developed  in  the  abdomen, 
and  descend  into  the  scrotum  about  the  eighth 
month  of  intra-uterine  life.  In  their  descent  they  push  before 
them  certain  coverings  derived  from  the  strata  of  the  abdominal 
walls,  through  which  they  pass,  and  which  constitute,  with  the 
layers  of  the  scrotum,  the  coverings  of  the  testes.  The  scrotum 
presents  in  the  middle  a  ridge,  the  raphe,  on  each  side  of  which  it 
is  corrugated  into  transverse  folds  or  rucjce.  It  is  divided  by  a  dis- 
tinct septum  into  two  lateral  halves,  of  which  the  left  is  the  longer. 
The  scrotum  consists  of  two  layers,  the  integument  and  the  dartos. 

The  integument  is  of  dark  colour,  thrown  into  transverse  rugas, 
and  provided  with  sebaceous  glands  and  hairs. 

The  dartos  is  a  thin  layer,  consisting  of  muscular  fibres  of  the 
involuntary  kind,  like  those  of  the  bladder  and  intestines.  It  serves 
to  corrugate  the  loose  and  extensible  skin  of  the  scrotum,  and  in 
a  measure  to  support  and  brace  the  testes.  It  is  more  abundant 
in  the  anterior  than  the  posterior  part  of  the  scrotum.  Beneath 
the  dartos,  and  partly  intermingled  with  it,  is  a  large  quantity  of 
loose  connective  tissue,  remarkable  for  the  total  absence  of  fat. 
Together  with  the  dartos  it  forms  a  vertical  partition  between  the 
testes,  termed  the  septum  scroti,  which  passes  from  the  raphe  to  the 
under  aspect  of  the  penis,  as  far  as  its  root.  It  is  not  a  complete 
partition,  since  air  or  fluid  will  pass  from  one  side  to  the  other. 
The  great  abundance  and  looseness  of  this  tissue  explains  the 
enormous  swelling  of  the  scrotum  in  cases  of  anasarca,  and  in  cases 
where  urine  is  extravasated  into  it  in  consequence  of  rupture  or 
ulcer ation  of  the  urethra. 

The  coverings  of  the  testes,  in  addition  to  these  two  layers  of  the 


THE   SCROTUM   AND   TESTES.  839 

scrotum,  are  the  intercolumnar  or  spermatic  fascia,  derived  from 
the  pillars  of  the  external  abdominal  ring,  the  cremasteric  fascia, 
derived  from  the  lower  border  of  the  internal  oblique  of  the  abdo- 
men, the  infundibuliform  fascia,  derived  from  the  fascia  transver- 
salis ;  and,  lastly,  the  tunica  vaginalis,  derived  from  the  parietal 
layer  of  the  peritoneum. 

The  spermatic  fascia,  cremaster  muscle,  and  the  infundibuli- 
form fascia  have  been  described  (pp.  427,  429,  436). 

Each  of  these  coverings  cannot  be  demonstrated  under  ordinary 
circumstances,  because  they  are  so  blended  together  :  but  they 
can  be  shown  when  hypertrophied  in  the  case  of  old  and  large 
herniae. 

The  arteries  supplying  the  tissues  of  the  testis  are  the  cremas- 
teric branch  of  the  deep  epigastric  artery,  the  superficial  and  deep 
external  pudic  branches  of  the  common  femoral  artery,  and  the 
superficial  perineal  branch  of  the  internal  pudic  artery. 

The  nerves  are  derived  from  the  ilio-inguinal,  the  genital 
branch  of  the  genito-crural,  the  superficial  perineal  nerves,  and  the 
inferior  pudendal  branch  of  the  lesser  sciatic  nerve. 

The  lymphatics  pass  to  the  inguinal  glands. 

The  testis  is  a  gland  of  an  oval  shape  with 
flattened  sides,  suspended  obliquely  in  the  scrotum 
by  the  spermatic  cord,  so  that  its  upper  end  is  directed  forwards 
and  outwards,  its  lower  end  in  the  reverse  direction.  The  left  is 
generally  a  little  lower  of  the  two.  Each  testis  is  from  an  inch 
and  a  half  to  two  inches  in  length,  an  inch  in  breadth,  and  an  inch 
and  a  quarter  from  behind  forwards.  Its  weight  is  from  six  to 
eight  drachms,  but  few  organs  present  greater  variations  in  size 
and  weight,  even  in  men  of  the  same  age ;  generally  speaking,  the 
left  is  the  larger.  The  front  and  sides  of  the  testis  are  convex  and 
smooth,  and  are  covered  with  the  visceral  layer  of  the  tunica 
vaginalis ;  but  the  posterior  surface  is  only  partially  invested,  as 
there  is  here  placed  a  long  narrow  body,  termed  the  epididymis ; * 
this  is  not  a  part  of  the  testis,  but  an  appendage  to  it,  formed  by 
the  convolutions  of  its  long  excretory  duct. 

The  epididymis  consists  of  a  larger  upper  end  called  the  globv* 
1  From  SiSv/j.os,  a  testicle. 


840 


THE    TESTIS. 


major  (fig.  207,  5)  and  of  a  lower  smaller  end,  the  globus  minor 
(fig.  207,  6),  the  two  being  connected  together  by  the  body.  The 
globus  major  is  connected  with  the  testicle  by  radiating  efferent 
ducts ;  the  globus  minor  is  only  connected  with  the  organ  by  con- 
nective tissue  and  the  tunica  vaginalis.  The  upper  and  lower  ends 
and  the  outer  surface  of  the  epididymis  are  covered  with  serous 
membrane,  as  is  also  the  body,  except  at  its  anterior  border,  where 
the  vessels  enter  and  emerge.  Situated  between  the  globus  major 
and  the  body  of  the  testis  are  one  or  two  small  pedunculated 
bodies,  called  the  hydatids  of  Morgagni  •  they  are  formed  by  pouch- 

FIG.  207. 


1.  Mediastinum  testis,  con- 

taining the  rete  testis. 

2,  2.  Trabeculse. 

3.  One  of  the  lobules. 

4,  4.  Vasa  recta. 


5.  Coni  vasculosi,  forming  the 

'  globus  major '  of  the  epi- 
didymis. 

6.  Globus  minor,  or  lower  end 

of  epididymis. 

7.  Vasdeferens. 


DIAGRAM   OF   A   VERTICAL   SECTION   THROUGH    THE    TESTICLE. 

ings  of  the  tunica  vaginalis,  and  are  filled  with  blood-vessels  bound 
together  by  connective  tissue.1 

A  considerable  quantity  of  unstriped  muscular  tissue  exists  at 
the  posterior  part  of  the  epididymis  and  testis  beneath  the  infundi- 
buliform  fascia,  and  has  been  described  by  Kolliker  as  the  inner 
muscular  tissue. 

COVERINGS  OP  The  testicle  is  invested  by  three  coverings,  which 

THE  TESTICLE.          are__i  ^    A   serous  membrane,   called   the    tunica 
vaginalis,  to  facilitate  its  movements.     2.  A  strong  fibrous  mem- 

1  The  largest,  which  lies  upon  the  top  of  the  testis,  is  stated  to  be  the  vestige 
of  the  Miillerian  duct. 


THE   TESTIS.  841 

brane,  called  the  tunica  albuginea,  to  support  the  glandular  struc- 
ture within.  3.  A  delicate  vascular  stratum,  termed  the  tunica 
vasculosa,  which  consists  of  a  layer  of  minute  blood-vessels. 

The  tunica  vaginalis  is  a  closed  serous  sac,  one  part  of  which, 
tunica  vaginalis  propria,  adheres  closely  to  the  testis  ;  the  other, 
tunica  vaginalis  reflexa,  is  the  reflected  portion,  adherent  to  the 
inner  surface  of  the  infundibuliform  fascia,  and  loosely  surrounds 
the  testicle.  On  opening  the  sac,  it  will  be  seen  that  the  visceral 
layer  completely  covers  the  testicle,  except  behind,  where  the 
vessels  and  duct  are  situated  (fig.  207)  ;  and  that  it  covers  the 
outer  part  of  the  epididymis  in  front  and  behind,  forming  here  a 
pouch  called  the  digital  fossa.  The  parietal  layer  extends  upwards 
for  a  variable  distance  upon  the  cord  and  below  the  testicle.  The 
interior  of  the  sac  is  smooth  and  polished,  like  all  other  serous 
membranes,  and  lubricated  by  a  little  fluid.  An  excess  of  this 
fluid  gives  rise  to  the  disease  termed  hydrocele. 

The  portion  of  the  process  of  peritoneum  between  the  internal 
abdominal  ring  and  the  upper  part  of  the  tunica  vaginalis  testis 
(the  spermatic  portion  of  the  tunica  vaginalis)  becomes,  in  the 
process  of  development,  converted  into  a  fibrous  cord,  which  may 
usually  be  recognised,  but  which  is  sometimes  so  atrophied  as  not 
to  be  recognised. 

The  tunica  vaginalis  testis  was  originally  derived  from  the 
peritoneum.  In  some  subjects  it  still  communicates  with  that 
cavity  by  a  narrow  canal,  and  is  therefore  liable  to  become  the  sac 
of  a  hernia  (see  diagram,  p.  444).  Such  hernige  are  called  con- 
genital—a misleading  term,  since  they  do  not  necessarily  take 
place  at  birth,  but  may  occur  at  any  period  of  life,  even  in  very 
old  age.1  Sometimes  the  communication  continues  through  a  very 
contracted  canal,  open  to  the  passage  of  fluid  alone  ;  or  the  com- 
munication may  be  only  partially  obliterated,  and  then  one  or 
more  isolated  serous  sacs  are  left  along  the  cord.  Such  a  one, 
when  distended  with  fluid,  gives  rise  to  hydrocele  of  the  cord. 

The  tunica  albuginea  is  a  dense,  white,  inelastic  membrane, 

1  It  would  be  a  better  term  to  call  this  lesion  a  hernia  in  the  tunica  vaginalis, 
denoting  thereby  its  anatomical  position ;  at  the  same  time  implying  a  congenital 
arrest  in  development,  and  without  limiting  its  occurrence  to  any  age  of  life. 


842 


THE   TESTIS. 


composed  of  white  fibrous  tissue,  interlacing  in  every  direction ; 
analogous  to  the  sclerotic  coat  of  the  eye.  It  completely  invests 
the  testis,  but  not  the  epididymis.  It  is  covered  by  the  visceral 
layer  of  the  tunica  vaginalis,  except  behind  and  at  the  attachments 
of  the  epididymis.  At  the  posterior  part  of  the  gland  it  penetrates 
into  its  substance  for  a  short  distance,  and  forms  an  incomplete 
vertical  septum,  termed,  after  the  anatomist  who  first  discovered 
it,  corpus  Highmorianum,  and  subsequently  by  Sir  A.  Cooper, 
mediastinum  testis  (fig.  208,  5). 

The   mediastinum   testis   transmits   the    blood-vessels    of  the 
organ,  and  contains  also  the  network  of  seminal  ducts,  called  the 

FIG.  208. 


1.  Spermatic  artery. 

2.  Vas  deferens. 

3.  Deferential  artery. 


4.  Epididymis. 

5.  Mediastinum  testis. 

6.  6.  Cavity  of  tunica 

vaginalis. 


TRANSVERSE    SECTION    THROUGH    THE    LEFT    TESTICLE. 

(The  dots  show  the  reflections  of  the  tunica  vaginalis.) 

rete  testis,  shown  in  the  diagram  (fig.  207).  This  septum  gives 
off  from  its  front  and  sides  a  number  of  diverging  slender 
fibrous  cords,  trabeculce  testis,1  which  traverse  the  interior  of  the 
gland,  and  are  attached  to  the  inside  of  the  tunica  albuginea. 
They  serve  to  maintain  the  general  shape  of  the  testicle,  to 
support  the  numerous  lobules  of  which  its  glandular  substance 
is  composed,  and  to  convey  the  blood-vessels  into  it.  These 
septa,  as  well  as  the  mediastinum  from  which  they  proceed,  are 
readily  seen  on  making  a  transverse  section  through  the  gland 
(fig.  208). 

1  Kolliker  has  demonstrated  unstriped  muscular  fibres  upon  the  septa  as  well 
as  the  mediastinum. 


THE    TESTIS.  843 

The  tunica  vasculosa  (pia  mater  testis)  consists  of  a  multitude  of 
minute  blood-vessels,  formed  by  the  ramifications  of  the  spermatic 
artery,  and  held  together  by  delicate  areolar  tissue.  It  covers  the 
inner  surface  of  the  tunica  albuginea,  and  gives  off  branches,  which 
ran  with  the  fibrous  septa  into  the  interior  of  the  gland. 

Minute  structure. — When  the  testis  is  cut  into,  its  surfaces 
become  convex,  and  present  a  dirty  fawn  colour.  The  section  is 
soft  and  pulpy,  and  is  seen  to  consist  of  numerous  lobules,  between 
two  hundred  and  fifty  and  four  hundred  in  number,1  of  various 
sizes,  the  central  being  the  larger,  and  contained  in  the  compart- 
ments formed  by  the  fibrous  septa  proceeding  from  the  mediastinum 
testis.  A  few  only  of  these  lobules  are  shown  in  the  diagram. 
These  lobules  are  conical  in  shape,  their  bases  being  anterior  and 
their  apices  at  the  mediastinum,  and  are  bounded  by  the  septa  which 
pass  from  the  mediastinum.  They  contain  two  or  more  minute  con- 
voluted tubes,  tubuli  seminiferi,  which  may  be  easily  unravelled,  in 
consequence  of  their  tough  walls.  Their  number  has  been  estimated 
to  be  between  800  and  900,  and  each  has  a  length  of  about  two 
feet  and  a  diameter  averaging  y-^th  of  an  inch.  They  commence 
either  by  communications  with  other  tubes  or  by  caecal  extremities, 
and  they  frequently  exhibit  small  bulgings  in  their  course  back- 
wards. The  walls  of  the  tubuli  consist  of  a  membrana  propria, 
composed  of  several  layers  of  flattened  cells,  and  the  walls  are 
lined  with  several  irregular  layers  of  cells,  between  which  may, 
under  the  microscope,  be  distinguished  seminal  filaments  in  various 
stages  of  development.  The  tubuli  seminiferi  are  connected  to- 
gether by  a  delicate  interstitial  tissue,  the  laminas  of  which  are 
surrounded  by  flattened  epithelioid  cells,  and  between  them  are 
lymph-spaces  in  direct  communication  with  the  lymphatics  of  the 
testicle.  In  this  intertubular  tissue  ramify  the  minute  branches 
of  the  spermatic  artery  which  surround  the  tubules. 

After  pursuing  a  convoluted  course,  the  tubules  unite  in  front 
of  the  mediastinum  into  from  thirty  to  fifty  straight  vessels,  vasa 
recta,  which  penetrate  the  mediastinum  testis,  and  these  form  an 
anastomosing  plexus  of  seminal  tubes,  called  the  rete  testis  (fig.  207). 
This  lies  along  the  back  of  the  gland.  From  the  upper  part  of  the 
1  The  larger  estimate  is  that  by  Krause  ;  the  smaller,  that  by  Berres. 


844  THE   TESTIS. 

rete,  its  tubes  converge  to  form  twelve  to  fifteen  tubes,  termed  vasa 
efferentia,  which  perforate  the  tunica  albuginea,  and  convey  the 
seminal  secretion  to  the  upper  part  of  the  epididymis.  The  vasa 
efferentia  are  at  first  straight,  but  ultimately  form,  a  number  of 
coils  termed  coni  vasculosi,  which  collectively  constitute  the  globus 
major  of  the  epididymis.  The  coni  vasculosi  are  about  -g^th  of  an 
inch  in  diameter,  and  about  six  to  eight  lines  long ;  when  unravelled 
they  attain  a  length  of  six  to  eight  inches. 

At  the  globus  major  the  smaller  tubes  terminate  in  a  single 
duct,  the  canal  of  the  epididymis,  which  in  its  descent  describes  an 
extremely  tortuous  coil,  constituting  the  body  and  globus  minor 
of  the  epididymis.  The  length  of  the  canal  of  the  epididymis  is, 
in  its  natural  condition,  about  three  inches,  but  when  unravelled 
it  is  nearly  twenty  feet  in  length.  The  diameter  of  the  canal  at 
its  commencement  is  about  ^"th  of  an  inch  ;  at  the  globus  minor 
about  -^th  of  an  inch,  after  which  it  again  increases  in  diameter. 
It  is  lined  with  columnar  ciliated  epithelium. 

The  vas  deferens  begins  at  the  lower  part  of  the 
globus  minor ;  at  first  it  is  somewhat  convoluted, 
but,  as  it  ascends  behind  the  epididymis,  it  becomes  subsequently 
straight,  and  joins  the  other  component  parts  of  the  cord.  After 
passing  through  the  inguinal  canal,  it  enters  the  abdomen  through 
the  internal  ring.  It  then  winds  round  the  outer  side  of  the  deep 
epigastric  artery,  and,  after  crossing  over  the  external  iliac  artery 
and  vein,  it  enters  the  pelvis,  curves  round  the  side  and  lower  part 
of  the  bladder,  and  empties  itself  into  the  prostatic  part  of  the 
urethra,  after  running  a  course  of  about  two  feet.  Its  course  in 
the  abdomen  has  been  previously  described  (p.  535). 

In  connection  with  the  anterior  aspect  of  the  cord,  just  above 
the  epididymis,  are  two  or  three  small  masses  of  convoluted  tubes, 
which  are  known  as  the  organ  of  Gir  aides,  or  the  par  epididymis. 
They  are  lined  with  squamous  epithelium,  and  are  probably  the 
remains  of  part  of  the  Wolffian  body. 

The  vas  aberrans  is  a  small  convoluted  tubule,  with  a  cascal 
extremity,  found  between  the  epididymis  and  the  cord,  and  com- 
municating usually-with  the  canal  of  the  epididymis.  It  is  about 
an  inch  in  length,  but,  when  frayed  out,  varies  from  two  to  twelve 


SPERMATIC   CORD.  845 

inches  in  length.  It,  like  the  organ  of  Giraldes,  is  connected  with 
a  foetal  structure — the  Wolffian  body. 

The  vas  deferens  consists  of  an  external  or  connective-tissue 
coat ;  a  middle  or  muscular  coat,  composed  of  longitudinal  and 
circular  fibres  intermingled  with  elastic  tissue ;  and  an  internal  or 
mucous  coat,  arranged  in  longitudinal  folds,  and  lined  with  columnar 
epithelium.  It  can  always  be  recognised  from  the  other  constituents 
of  the  spermatic  cord  by  its  hard  whipcord-like  feel. 

SPEKMATIC  The  spermatic  cord  begins  at  the  internal  ring, 

CORD.  traverses  the  inguinal  canal,  and  extends  to  the 

testis,  where  its  component  parts  pass  to  their  respective  desti- 
nations. It  is  composed  of  the  spermatic  vessels,  nerves,  and 
lymphatics  ;  of  the  vas  deferens,  with  the  deferential  artery,  a 
branch  of  the  superior  vesical ;  of  the  cremaster  muscle,  and  the 
cremasteric  artery,  a  branch  of  the  deep  epigastric.  The  coverings 
of  the  cord  have  been  described  with  the  anatomy  of  the  parts 
concerned  in  inguinal  hernia  (p.  439). 

The  spermatic  artery  in  its  course  along  the  cord  becomes 
remarkably  tortuous ;  it  enters  the  back  part  of  the  testicle,  and 
breaks  up  into  a  number  of  fine  ramifications,  which  spread  out  on 
the  inner  surface  of  the  tunica  albuginea. 

The  spermatic  veins  leave  the  testis  at  its  back  part,  and,  as 
they  ascend  along  the  cord,  become  extremely  tortuous  and  form  a 
plexus,  termed  the  pampiniform  plexus.  They  lie  in  front  of  the 
vas  deferens  and  unite  to  form  a  single  vein,  which  on  the  right 
side  opens  into  the  inferior  vena  cava,  and  on  the  left  side  into  the 
left  renal  vein.  It  is  usually  stated  that  these  veins  are  destitute 
of  valves ;  and  this  fact  is  adduced  as  one  of  the  reasons  for  the 
occurrence  of  varicocele.  It  is,  however,  certain  that  the  larger 
veins  do  contain  valves. 

The  lymphatics  of  the  testis  pass  through  the  lumbar  glands  ; 
hence  these  glands,  and  not  the  inguinal,  become  affected  in  malig- 
nant disease  of  the  testis. 

The  nerves  of  the  testicle  are  derived  from  the  sympathetic. 
They  descend  from  the  abdomen  with  the  spermatic  arteries,  and 
come  from  the  aortic  and  renal  plexuses,  with  a  few  filaments  from 
the  hypogastric  plexus,  which  surround  the  deferential  artery 


846  DESCENT   OF   THE   TESTIS. 

(p.  540).  This  accounts  for  the  ready  sympathy  of  the  stomach 
and  intestines  with  the  testicle,  and  for  the  constitutional  effects  of 
an  injury  to  it. 

DESCENT  OF  The  testicle  is  originally  developed  in  the  lumbar 

THE  TESTIS.  region,  immediately  below  the  kidney,  and  is  loosely 

attached  to  the  back  of  the  abdomen  by  a  fold  of  peritoneum, 
termed  the  mesorchium,  along  which  its  vessels  and  nerves  run  up 
to  it,  as  to  any  other  abdominal  viscus.  From  the  lower  end  of 
the  gland  a  fibrous  cord,  termed  the  gubernaculum  testis,1  pro- 
ceeds to  the  bottom  of  the  scrotum.  There  is  no  evidence  to 
warrant  the  assumption  that  the  gradual  contraction  of  the  guber- 
naculum effects  the  descent  of  the  testis.  The  organ  begins  to 
descend  from  the  lumbar  region  about  the  fifth  month  of  foetal  life, 
reaches  the  internal  ring  about  the  seventh,  and  about  the  ninth 
has  entered  the  scrotum.  Its  original  peritoneal  coat  is  retained 
throughout;  but  as  it  enters  the  inguinal  canal,  the  peritoneal 
lining  of  the  abdomen  is  pouched  out  before  it,  and  eventually 
becomes  the  tunica  vaginalis  reflexa.  Immediately  after  the 
descent  of  the  testis,  its  serous  bag  communicates  with  the 
abdomen,  and  in  the  lower  animals  continues  to  do  so  throughout 
life.2  But  in  the  human  subject  the  canal  of  communication  soon 
begins  to  close.  It  closes  at  the  upper  extremity  first,3  and  the 
closure  is  generally  complete  in  a  child  born  at  its  full  time.4 
This  provides  against  the  occurrence  of  ruptures,  to  which  man, 

1  Mr.  Curling  considers  the  gubernaculum  testis  to  be  a  muscular  cord.     See 
his  Observations  on  the  Structure  of  the  Gubernaculum,  and  on  the  Descent  of  the 
Testis  in  the  Foetus  :  Medical  Gazette,  April  10,  1841.     This  is  denied  by  Cleland, 
see  Meclwnism  of  the  Gubernaculum  Testis,  1856. 

2  According  to  Professor  Owen,  the  African  orang-outang  (Simia  troglodytes]  is 
the  only  exception  to  this  rule.     In  this  animal  it  is  interesting  to  observe  that  the 
lower  extremities  are  more  fully  developed  as  organs  of  support,  and  there  is  a 
ligamentum  teres  in  the  hip- joint. 

8  The  frequency  of  hernia  in  the  funicular  portion  of  the  vaginal  process  of  the 
peritoneum  hardly  bears  this  out. 

4  Camper  has  shown  that  the  canal  on  the  right  side  is  nearly  always  open  at 
birth,  whereas  that  on  the  left  is  usually  closed.  This  explains  the  greater  fre- 
quency of  hernia  on  the  right  side  in  children  under  one  year  old.  Thus  out  of 
3,014  cases  of  inguinal  hernia  seen  at  the  City  of  London  Truss  Society  under  one 
year,  2,269  occurred  on  the  right  side,  and  745  on  the  left ;  or  in  the  proportion  of 
3tol. 


DESCENT    OF   THE    TESTIS.  847 

owing  to  his  erect  position,  is  more  exposed  than  animals.  At  the 
end  of  the  first  month  after  birth,  the  canal  is  entirely  obliterated 
from  the  internal  ring  to  the  testis.  Sometimes,  however,  this 
obliteration  fails,  or  is  only  partial ;  hence  may  arise  congenital 
hernia,  or  hydrocele.  The  possible  existence  of  a  communication 
between  the  tunica  vaginalis  and  the  peritoneal  cavity  of  the 
abdomen,  is  one  reason,  among  many,  why  caution  should  be 
observed  in  treating  hydroceles  in  children  with  stimulating 
injections. 


INDEX. 


ABD 

Abdomen,  dissection  of,  419 

parts  exposed  on  opening,  448 

regions  of,  419 

superficial  fascia  of,  421 

surface  marking  of,  419 
Abdominal  muscles,  functions  of,  433 

ring,  external,  427 
internal,  436 

walls,  arteries  of,  436 
nerves  of,  434 

Abducens,  nerve,  19,  60,  750 
Accelerator  urinte,  511 
Acervulus  cerebri,  769 
Achillis,  tendo,  675 
Adami,  pomum,  240 
Adductor  brevis,  631 

longus,  629 

magnus,  632 
Ala  cinerea,  773 

Alimentary     canal,    anastomoses     on, 
606 

length  of,  454 
Ampulla  of  semicircular  canals,  826 

of  rectum,  531 
Amygdala  cerebelli,  776 
Anal  glands,  506 

fascia,  528 

Anastomoses,  alimentary  canal,  606 
Angular  artery,  40 

vein,  41 
Ani,  sphincter,  508 

levator,  538 
Ankle-joint,  ligaments  of,  707 

movements  of,  709 
Annular  ligament  of  hand,  358 

posterior  ligament  of  forearm,  389 

ligament  of  ankle,  646 
Annulus  ovalis,  200 
Ansa  hypoglossi,  85,  110 
Antitragus,  816 


ART 

Antihelix,  816 

fossa  of,  816 
Aorta,  abdominal,  481 

arch,  course  of,  174 

descending  thoracic,  182 
great  sinus  of,  176 
relations  of,  175 
ascending  part  of,  176 
descending  part  of,  177 
transverse  part  of,  176 
Aponeurosis,  epicranial,  2 

gluteal,  616 

lumbar,  373 

pharyngeal,  226,  230 

supra-hyoid,  93 

vertebral,  279,  373 
Apparatus  ligamentosus  colli,  29& 
Aquseductus  cochleas,  827 

Fallopii,  268 

Sylvii,  771 

vestibuli,  825 
Arachnoid  membrane  of  brain,  715 

cavity  of,  8 

of  spinal  cord,  783 
Arantius,  corpus  of,  204 

nodules  of,  204 
Arbor  vit£e  of  cerebellum,  778 

uterus,  569 
Arch,  crural,  426,  619 

parts  passing  under,  620 

deep,  622 
Arm,  upper,  cutaneous  nerves  of,  325 

musculo-cutaneous  nerve  of,  337 

surface  marking  of,  324 
Arnold's  ganglion,  146 

nerve,  6,  147 
Arteries : 

acromial  thoracic,  310 

alar  thoracic,  317 

alveolar,  136 

3l 


850 


INDEX. 


ART 

Arteries  (continued) 

anastomotica  magna  of  brachial,  335 
femoral,  641 
angular,  40 
anterior  cerebral,  717 
ciliary,  804 
communicating,  718 
perforating,  of  foot,  689 
peroneal,  682 
spinal,  719 

superior  cerebellar,  720 
tibial,  649 
aorta,  174 

abdominal,  481 

branches  of.  464 
arch  of,  175 

ascending,  176 
descending,  177 
transverse,  176 
descending  thoracic,  182 
articular,  of  knee,  668 
auditory,  720,  835 
auricular  anterior,  128 

posterior,  4 
axillary,  315 
azygos,  677 
back,  291 
fcasilar,  719 

transverse  of,  720 
bicipital,  178 
brachial,  332 
brachio-cephalic,  178 
of  brain,  717 
bronchial,  194,  224 
buccal,  136 
bulb,  519 

calcanean  internal,  682,  688 
capsular,  581 
carotid,  common,  81,  179 
external,  95 

internal,  23,  144,  270,  717 
carpal  of  radial,  anterior,  347 
posterior,  347 
ulnar,  anterior,  349 

posterior,  349,  397 
centralis  modioli,  828 

retinae,  58,  812 

cerebellar,  anterior  superior,  720 
posterior  inferior,  720 

superior,  720 
cerebral  anterior,  717 
middle,  718 
posterior,  720 
cervical  ascending,  120 
superficial,  121,  376 


ART 

Arteries  (continued) 

transverse,  121 
cervicis  princeps,  107 

profunda,  123  » 

choroid  anterior,  719 

posterior,  720 
ciliary  anterior,  58 

long,  58 

short,  58 

circle  of  Willis,  719,  720 
eirculus  major,  804 

minor,  804 
circumflex  of  arm,  anterior,  319 

posterior,  318,  381 

thigh,  external,  639 

internal,  639 
circumflexa  ilii,  deep,  438,  492 

superficial,  423,  611 
coccygeal,  663 
coeliac  axis,  466 
colica  dextra,  472 

media,  472 

sinistra,  473 
comes  nervi  ischiatici,  663 

mediani,  352 

phrenici,  159 

'communicating  anterior,  of  tibial, 
682,  718 

posterior  of  tibial,  719 
coronaria  ventriculi,  466 
coronary,  207 
coronary,  of  lip,  inferior,  40 

superior,  40 

corpus  cavernosum,  519 
cremasteric,  437 
crico-thyroid,  96 
cystic,  468 
deep  cervical,  123 

external  pudic,  613 

palmar  arch,  365 

temporal,  135 
deferential,  540 
dental  anterior,  136 

inferior,  135 

superior,  136 
digital,  of  hand,  357 

toes,  688 

dorsalis  hallucis,  651 
indicis,  398 

linguae,  106 

pedis,  650 

pollicis,  398 
scapulae,  385 

dorsal  interosseous  of  hand,  397 
of  foot,  651 


INDEX. 


851 


ART 

Arteries  (continued) 

dorsal,  of  penis,  519 
epigastric,  deep,  437 

superficial,  423 
ethmoidal  anterior,  58 

posterior,  58 
facial,  38,  98 
femoral,  630 

superficial,  631 

deep,  638 
frontal,  4,  59 
gastric,  466 
gastro-duodenalis,  468 
gastro-epiploica  dextra,  468 

sinistra,  468 
gluteal,  540,  657 

inferior,  663 
helicine,  561 
hffimorrhoidal  external,  508 

middle,  541 

superior,  473 
hepatic,  467,  580 
hyoid  inferior,  96 

superior,  106 
hypogastric,  540 
ileo-colic,  472 
iliac  common,  490 

external,  492 

internal,  539 
ilio-lumbar,  539 
inferior  labial,  39 
infraorbital,  48,  136 
infraspinous,  121,  376 
innominate,  178 
intercostal,  190,  436 

anterior,  159 

collateral,  191 

dorsal  of,  191 

superior,  122 
interlobular,  581 
interosseous,  anterior,  352 

common,  of  forearm,  349 

of  hand,  366 

posterior,  395 

recurrent,  395 
intestini  tenuis,  472 
labial  inferior,  39 

superior,  40 
lachrymal,-  58 
laryngeal,  superior,  96 
lateral,  of  nose,  40 

sacral,  540 

spinal,  719 
lingual,  105 
long  ciliary,  804 


ART 

Arteries  (continued) 
lumbar,  485 
malleolar,  650 
mammary,     internal,     122,     159, 

436 

masseteric,  135 
mastoid,  108 
maxillary,  external,  38 

internal,  133 
mediastinal,  159 
meningea  media,  134 

parva,  16,  135 
meningeal,  16 

anterior,  16 

middle,  16 

posterior,  16,  107,  719 
mental,  49 
mesenteric,  inferior,  473 

superior,  472 
metatarsal,  651 
middle  cerebral,  718 

hffimorrhoidal,  541 

sacral,  543 

temporal,  128 

vesical,  540 
muscular,  to  eye,  59 
musculo-phrenic,  159,  437 
mylo-hyoid,  135 
nasal,  59,  136 
nutrient,  of  femur,  640 

humerus,  335 
obturator,  541,  643 

pubic  branch  of,  541 
occipital,  4,  107 
cesophageal,  194 

of  gastric,  466 
omental,  469 
ophthalmic,  57 
orbital,  134 
ovarian,  485 
palatine,  ascending,  98,  143 

descending,  136 
palmar  arch,  deep,  365 

superficial,  355 

interosseous,  366 
palmaris  profunda,  365 
palpebral,  inferior,  59 

superior,  59 
pancreatic,  468 
pancreatico-duodenal,  inferior,  472 

superior,  468 
perforating,  of  hand,  366 

foot,  689 

thigh,  640 

intercostal,  159 

3  i  2 


852 


INDEX. 


ART 

Arteries  (continued) 
pericardiac,  159 
perineal,  superficial,  510 

transverse,  511 
plantar,  external,  688 

internal,  687 
peroneal,  681 

anterior,  682 
petrosal,  16,  134 
pharyngeal,  ascending,  109,  145 
meningeal  of,  109 
pharyngeal,  branches  of,  145 
phrenic,  482 
popliteal,  667,  676 

articular  branches  of,  677 
branches  of,  667 
posterior  communicating,  719 
profunda  inferior,  333 
superior,  333,  387 
princeps  pollicis,  365 
pterygoid,  136 
pterygo-palatine,  136 
pubic,  of  deep  epigastric,  437 

'obturator,  541 
pudic,  internal,  517,  542,  663 
deep  external,  613 
superficial  external,  423,  611 
pulmonary,  194,  223 
pyloric,  468 
radial,  346 

in  palm,  365 
at  back  of  wrist,  397 
recurrent,  347 
radialis  indicis,  365 
ranine,  106 
receptaculi,  23 
rectum  of,  532 
renal,  484,  593 

branches  of,  594 
sacral,  lateral,  540 

middle,  486,  548 
scalp,  of,  4 
scapulas  dorsalis,  318 
scapular,  posterior,  121,r376 

supra-,  121,  375 
sciatic,  542,  662 
septum  of  the,  40,  136 
sigmoid,  473 
spermatic,  484,  845 
spheno-palatine,  136 
spinal,  anterior,  719 
lateral,  120 
posterior,  719 
splenic,  468,  587 
sternal,  159 


ART 

Arteries  (continued) 

sterno-mastoid,  inferior,  121,  375- 
middle,  96 

superior,  107 
stylo-mastoid,  108 
subclavian,  left,  115,  179 

right,  113 
sublingual,  106 
submaxillary,  98 
submental,  98 
subscapular,  317 
superficialis  volse,  347 
supra-acromial,  121,  375 
supra-orbital  4,  58 
supra-renal,  484 
supra-scapular,  121,  375 

subscapular  of,  121 
sural,  678 
tarsal,  651 
temporal,  127 

deep,  135 

superficial,  4 
testis,  of,  839 
thoracica-acromialis,  310 

alaris,  317 

longa,  317 

superior,  310 
thymic,  159 
thyroid  axis,  120 

inferior,  120 

superior,  96 
tibial,  anterior,  649 

posterior,  681 

recurrent,  650 
tonsillar,  98 
transverse  cervical,  121 

facial,  41 

transversalis  perinei,  511 
tympanum,  of,  824 
ulnar,  348 

anterior  recurrent,  349 

posterior  recurrent,  349 
ulnaris,  profunda,  357 
uterine  566 
vaginal,  567,  581 
vasa  brevia,  468 
vertebral,  119,  719 

lateral  spinal  of,  120,  719 

posterior  meningeal  of,  719 
vesical,  inferior,  540 

middle,  540 

superior,  540 
Vidian,  136 

Articulations,  acromio-clavicular,  403 
ankle,  707 


INDEX. 


853 


ART 

Articulations  (continued) 

astragalo-calcanean,  709 

astragalo-scaphoid,  710 

atlo-axoid,  300 

calcaneo-cuboid,  711 

calcaneo-scaphoid,  710 

carpal,  413 

carpo-metacarpal,  415 

costo-sternal,  302 

elbow,  408 

hip,  696 

interphalangeal,  418,  714 

metacarpal,  416 

metacarpo-phalangeal,  417 

metatarsal,  713 

metatarso-phalangeal,  714 

occipito-atlantal,  298 

pubic,  696 

radio-carpal,  412 

radio-ulnar,  inferior,  411 
superior,  409 

sacro-coccygeal,  694 

sacro-iliac,  694 

sacro-vertebral,  693 

scapulo-clavicular,  403 

shoulder,  405 

sterno-clavicular,  401 

tarsal,  711 

tarso-metarsal,  713 

temporo-maxillary,  303 

tibio-fibular,  inferior,  707 
superior,  706 

trapezium  and  thumb,  415 

wrist,  412 
Aryteno-epiglottideus,  249 

inferior,  251 

superior,  251 

Aryteno-epiglottidean  folds,  244 
Arytenoid  cartilages,  242 
Arytenoideus,  249 
Atrium  of  auricle,  199 
Auditory  meatus,  external,  818 

nerve,  19,  751,  834 
Auerbach's  plexus,  604 
Aurem  attollens,  3 

attrahens,  3 

retrahens,  3 
Auricle  of  ear,  816 
Auricle  of  heart,  right,  199 

left,  205 

muscular  fibres  of,  210 
Auricular  appendix,  199 

artery,  anterior,  128 
posterior,  108 

great,  nerve,  68 


BRA 


Auricular  nerve,  147 

posterior,  6,  108 

nerve  of  pneumogastric,  6 

vein,  4,  108 

Auriculo-temporal  nerve,  6,  128,  139 
Axilla,  dissection  of,  312 
Axillary  artery,  315 

ligature  of,  311 

fascia,  312 

plexus  of  nerves,  320 

vein,  319 
Axis  cosliac,  466 

thyroid,  120 
Azygos  artery,  677 

veins,  182,  183 

Back,  arteries  of,  291 

cutaneous  nerves  of,  367 

muscles  of,  278 

nerves  of,  289 
Band,  ilio-tibial,  615 
Bartholin,  duct  of,  104 

glands  of,  523 
Basilic  vein,  327 
Bell,  nerve  of,  324 
Bertini,  columns  of,  590 
Bichat,  fissure  of,  762 
Biliary  ducts,  581 
Biceps  of  arm,  329,  406 

thigh,  669 
Bladder,  532 

arteries  of,  551 

female,  563 

ligaments  of,  503,  526,  529 

nerves  of,  551 

position  of,  532 

sphincter  of,  548 

structure  of,  548 

trigone  of,  550 

uvula  of,  550 

veins  of,  551 

Bochdalek,  ganglion  of,  260 
Brachial  artery,  332 

plexus  of  nerves,  320 
Brachialis  anticus,  331 
Braehio-cephalic  artery,  178 

veins,  172 
Brain,  715 

annectent  gyri,  738,  739 

arteries  of,  717  ' 

central  fissure  of,  735 

cornua  of,  758 

membranes  of,  8,  715 

removal  of,  12 

division  of,  721 


854 


INDEX. 


BRA 

Brain  (continued) 

fissures  of,  734,  735 
peculiarities  of  circulation  in,  721 
weight  of,  722 
Breasts,  836 
Bronchi,  217 
Bronchial  arteries,  194,  224 

lymphatic  glands,  195 
Bruch,  membrane  of,  801 
Brunner's  glands,  603 
Buccal  fascia,  37 

glands,  38 
Buccinator,  36 
Bucco-pharyngeal  fascia,  38 
Burns'  ligament,  618 
Bursse,  biceps,  near  tendon  of,  406 
of  carpus,  387 
over  knuckles,  387 
olecranon,  387 
patella,  636 

under  coraco-acromial  ligament,  381 
coraco-brachialis,  331 
deltoid,  381 
gastrocnemius,  674 
gluteus  maximus,  656 

medius,  656 
gracilis,  629 
latissimus  dorsi,  372 
ligamentum  patellte,  701 
obturator  internus,  659 
popliteus,  679 
Sartorius,  627 
semi-membranosus,  670 
subscapularis,  384 
teres  major,  383 
triceps,  386 
tuberosity  of  ischium,  507 


Crccum,  453 

meso-Cfficum,  463 
Calamus  scriptorius,  772 
Canal,  crural,  623 

femoral,  623 

of  Huguier,  824 

Hunter,  637 

inguinal,  438 

of  Niick,  505 

Petit,  814 

Schlemm,  799 

Stilling,  813 

Wirsung,  584 
Canaliculus,  30,  33 
Canalis  reuniens,  833 

spiralis  modioli,  828 


CER 

Canals,  semicircular,  8 

Canthi,  30 

Capsule,  Glisson's,  579 

of  Tenon,  51,  62,  794 
Capsules,  supra-renal,  595 
Caput  gallinaginis,  552 
Cardiac  nerves,  of  pneumogastric,  148r 
187 

sympathetic,  151 

plexus,  deep,  196 

superficial,  195 

Carotid  artery,  common,  81,  179 
ligature  of,  82 
difference  of  left,  83 
external,  95 

branches  of,  96 

internal,  144,  270,  717 
curves  of,  23 

plexus,  23,  151 

triangles,  76,  77 
Carpal  arteries,  397 
Carpus,  bursal  sac  of,  364 
Cartilages,  arytenoid,  242 

cornicula  laryngis,  242 

cricoid,  241 

cuneiform,  242 

epiglottis,  242 

of  larynx,  240 

of  nose,  271 

of  pinna,  816 

of  trachea,  267 

of  Wrisberg,  242 

tarsal,  32 

thyroid,  240 
Cartilago  triticea,  240 
Caruncula  lachrymalis,  30 
Carunculse  myrtiformes,  523 
Cava,  vena,  inferior,  486 

superior,  173 
Cavernous  plexus,  23,  152 

sinus,  14,  21 

structures    passing    through, 

21 
Centrum  ovale  majus,  754 

minus,  753 

Cephalic  vein,  311,  327 
Cerebelli,  falx,  9 

tentorium,  9 
Cerebellum,  774 

inferior  peduncles  of,  772 

middle  peduncles  of,  777 

superior  peduncles  of,  770 

structure  of,  777 

inferior  vermiform  process,  776 

superior  vermiform  process,  775 


INDEX. 


855 


CEB 

Cerebral    circulation,    peculiarities  of, 

721 

Cerebri,  falx,  9 
Cerebro-spinal  fluid,  716 

of  cord,  784 
Cerebrum,  732 

base  of,  742 

crura  of,  745 

development  of,  778 

hemispheres  of,  733 

labium  of,  742 

longitudinal  fibres  of,  774 

peduncular  fibres  of,  774 

structure  of,  773 

transverse  fibres  of,  774 

ventricles  of,  756,  760,  767,  771 
Cervicalis  ascendens  artery,  120,  283 

profunda,  123 

superficialis,  121 
Cervical  fascia,  64 

deep,  65,  69 

glands,  88 

plexus  of  nerves,  68 
Cervicis  princeps  artery,  107 
Cervical  plexus,  deep,  109 
superficial,  67 
Cervico-facial  nerve,  46 
Chambers  of  the  eye,  812,  813 
Check  ligaments,  299 
Chest,  surface  marking  of,  305 
Chorda  tympani  nerve,  141 
ChordtE  tendineas  of  ventricles,  203 

vocales,  246 

Willisii,  12 
Choroid  arteries,  719,  720 

coat  of  eye,  800 

plexus,  765 

Chyli  receptaculum,  184 
Cilia,  31 

Ciliary  arteries,  anterior,  58 
long,  58 
short,  58 

muscle,  802 

nerves,  long,  56 

processes,  801 
Circular  sinus,  14 
Circulation,  foetal,  213 
Circulus  major  and  minor,  804 
Circumflex  artery,  anterior,  319 
t         posterior,  318,  381 

nerve,  322,  381 
Circumflex,  external,  639 

iliac  artery,  deep,  438 
superficial,  611 

internal,  639 


COR 

Clitoris,  521 

erector  of,  521 

glans  of,  522 

prepuce  of,  522 
Coccygeal  gland,  486 
Coccygeus,  538 
Cochlea,  826 

canal  of,  828 

columella  of,  827 

modiolus,  827 

spiral  canal,  827 

Collateral  circulation  after  ligature  of 
axillary  artery,  319 

carotid,  83 

iliac,  external,  493 
common,  491 

innominate,  179 

femoral,  common,  641 
superficial,  641 

subclavian,  123 
Colon,  ascending,  454 

descending,  454 

transverse,  454 
Columns  of  Bertini,  590 
Columns,  carneas,  202 

rugarum,  564 
Complexus,  285 

Communicantes  noni  nerves,  110 
Commissure,  anterior,  767 

great  transverse,  754 

middle,  767 

of  cord,  787 

of  labium,  521 

optic,  749 

posterior,  768 

simplex,  776 

Coni  vasculosi  testis,  844 
Concha  of  ear,  806 
Conjunctiva,  30,  793 
Constrictors  of  pharynx,  228 
Conus  arteriosus,  202 

medullaris,  786 
Convolutions,  dentate,  742 

frontal,  737 

occipital,  739 

parietal,  738 

temporo-sphenoidal,  740 

uncinate  or  hippocampal,  742 
Cord,  spermatic,  439,  845 
Cornea,  796 
Cornicula  laryngis,  242 
Coronary  arteries  of  heart,  207 
inferior,  40 
superior,  40 

plexuses,  196 


856 


INDEX. 


COR 

Coronary  sinus,  201,  208 
Corpora  albicantia,  745 

quadrigemina,  769 
Corpus,  Arantii,  204 

callosum,  754 

ventricle  of,  754 

cavernosum  penis,  559 

dentatum  cerebelli,  778 

fimbriatum,  762 

geniculatum,  766 

Highmorianum,  842 

luteum  of  ovary,  574 

spongiosum,  561 

striatum,  762 
Corti,  organ  of,  830 

rods  of,  830 

tunnel  of,  830 

Costo-coracoid  membrane,  309 
Cotunnii  liquor,  832 
Cotunnius,  nerve  of,  262 
Cotyloid  ligament,  699 
Cowper's  glands,  517 

structure  of,  555 

Cranial    nerves,   dissection   to   expose, 
16 

exit  of,  16 

origin  of,  746 
Cremaster  muscle,  429 
Cribriform  fascia,  618 
Cricoid  cartilage,  241 

ligaments  of,  241 
Crista,  acustica,  833 

vestibuli,  825 
Crucial  anastomosis,  639 

ligaments,  703 
Crural  arch,  619 
deep,  622 

canal,  623 

nerve,  anterior,  498,  641 
Crusta  of  crus  cerebri,  748 
Crystalline  lens,  814 
Cuneiform  cartilages,  242 
Cuneus,  741 
Cupola  of  cochlea,  827 
Cuvier,  duct  of,  170 
Cystic  duct,  470 


Dartos  scroti,  838 
Deglutition,  mechanism  of,  237 
Deiters,  cells  of,  832 
Deltoid  muscle,  379 

parts  covered  by,  380 
Demours,  membrane  of,  799 


CIS 

Dental  artery,  inferior,  135 
superior,  136 

nerve,  inferior,  140 
Descemet,  membrane  of,  799 
Descent  of  testis,  846 
Diaphragm,  477 

arteries  of,  480 

central  tendon  of,  479 

crura  of,  478 

functions  of,  480 

nerves  of,  480 

openings  in,  479 
Digastric  muscle,  92 

triangle  and  contents,  91 
Diogenes,  cup  of,  354 
Dissection  of  the : 

abdomen,  419 

abdominal  viscera,  575 

axilla,  312 

back,  278 

muscles    of,    connected    with 
arm,  366 

brain,  715 

to  remove,  12 

cavernous  sinus,  21 

cranial  cavity,  8 

digastric  triangle,  91 

epicranial  region,  1 

eye,  792 

extremity,  lower,  609 
upper,  305 

face,  24 

femoral  hernia,  619 

foot,  sole  of,  683 

forearm,  back,  387 
front,  339 

gluteal  region,  653 

hand,  353 

hearing,  organ  of,  816 

heart,  198 

inguinal  hernia,  440 

larynx,  238 

leg,  back  of,  672 
front  of,  643 

mammary  gland,  836 

maxillary  nerve,  superior,  258 

neck,  63 

nose,  271 

orbit,  49 

pelvis,  side  view  of,  525 
viscera  of,  499 
female,  562 

perineum,  male,  505 
female,  521 

pharynx,  224 


INDEX. 


857 


DIS 

Dissection  (continued)  of  the  : 

pterygoid  region,  131 

scrotum,  838 

shoulder  muscles,  378 

spinal  cord,  780 

submaxillary  triangle,  91 

supra-clavicular  region,  75 

temporal  region,  127 

testis,  838 

thorax,  155 

tongue,  253 
Dorsal  nerves,  192 
Douglas,  semilunar  fold  of,  429 

pouch  of,  460 
Ducts,  or  duct,  of — - 

Bartholin,  104 

biliary,  581 

common  bile,  470 
hepatic,  581 

Cowper's  gland,  517 

Cuvier,  170 

cystic,  470,  583 

galactophorous,  837 

hepatic,  470 

nasal,  275 

pancreatic,  476,  585 

parotid  gland,  43 
.  prostate,  552 

Eivinus,  104 

Stenson's,  43 

sublingual  gland,  104 

thoracic,  184 

Wharton's,  140 

Wirsung,  583 
Ductus  arteriosus,  195 

communis  choledochus,  470,  583 
ejaculatorius,  535 

venosus,  fissure  of,  576 
Duodenum,  course  of,  450 

relations  of,  474 
Dura  mater,  8 

nerves  of,  9 

processes  of,  9 

sinuses  of,  10 

spinal  cord,  782 
Duverney's  glands,  523 


Ear,  816 

muscles,  3 

intrinsic,  817 

Eighth  pair  of  nerves,  19,  146,  751 
Ejaculatory  ducts,  535 
Elbow-joint,  408 

synovial  membrane  of,  409 


FAS 

Elbow-joint  (continued) 

triangle,  342 

veins  in  front  of,  327 
Eleventh  nerve,  20,  149,  752 
Eminence,  hypothenar,  353 

thenar,  353 
Eminentia  cinerea,  773 

collaterals,  765 
Endocardium,  210 
Endolymph  of  labyrinth,  825,  834 
Ependyma  ventriculorum,  756 
Epicardium,  210 
Epicranial  aponeurosis,  2 
Epididymis,  839 
Epiglottis,  242 

cushion  of,  245 

ligaments  of,  248 

mucous  folds  of,  243 
Eustachian  tube,  236,  820 

valve,  201 
Eye,  797 

lashes,  31 

lids,  30 
Exit  of  the  cranial  nerves,  16 


Face,  dissection  of,  24 

motor  nerves  of,  25 

sensory  nerves  of,  23,  47  • 
Facial  artery,  38,  98 

nerve,  19,  69,  267,  750 
on  face,  44 

transverse  artery,  41 

vein,  40,  94 
Fallopian  tubes,  571 

fimbriffi  of,  572 
Fallopii  aquasductus,  45 
Falx  cerebelli,  9 

cerebri,  9 
Fascia,  anal,  528 

arm,  328 

forearm,  341 

back  of  forearm,  388 

axillary,  312 

buccal,  37 

bucco-pharyngeal,  38 

cervical,  deep,  69 

costo-coracoid,  309 

cremasteric,  429 

cribriform,  618 

iliac,  487 

infundibuliform,  436 

intercolumnar,  427 

intermuscular  of  arm,  329 


853 


INDEX. 


FAS 

Fascia  (continued) 

ischio-rectal,  528 

lata  of  thigh,  615 

lumbar,  279 

metacarpus,  389 

muscular  of  arm,  328 

obturator,  528 

orbit,  51 

palmar,  354 

pelvic,  527 

perineal,  deep,  515 
superficial,  509 

pharyngeal,  226 

plantar,  684 

prevertebral,  70 

psoas,  487 

recto-vesical,  529 

semilunar  of  biceps,  330 

spermatic,  427 

temporal,  130 

transversalis,  435 
Fasciculi  graciles,  726 

teretes,  773 
Faucium  isthmus,  232 
Femoral  artery,  630 
in  canal,  637 

sheath  of,  621 

ring,  623 
Fenestra  ovalis,  820 

rotunda,  820 

Ferrein,  pyramids  of,  591 
Fibro-cartilages,    interarticular,    lower 
jaw,  303 

scapulo-clavicular,  404 

semilunar  of  knee,  703 

sterno-clavicular,  402 

wrist,  411 

Fifth  cranial  nerve,  18,  137,  258,  749 
Filum  terminale,  785 
Fimbriae  of  Fallopian  tube,  572 
Fissures,  Bichat,  762 

calcarine  of  brain,  740 

calloso-marginal  of  brain,  740 

horizontal,  775 

longitudinal,  753 

palpebral,  30 

parieto-occipital,  737 

praecentral,  734 

primary  of  brain,  734 

Eolando,  736 

Santorini,  817 

sphenoidal,  nerves  in,  21 

Sylvius,  734 

triradiate,  738 
Flocculus,  776 


GAN 

Foetal  circulation,  213 

changes  at  birth,  215 
Folds,  ary-epiglottic,  244 

glosso-epiglottic,  244,  254 

Houston's,  606 

hepato-renal,  459 

rectal,  606 

Follicles,  Graafian,  574 
Fontana,  spaces  of,  799 
Foot,  cutaneous  nerve  of  sole,  684 
Forearm,  cutaneous  nerves  of,  340 
back  of,  388 

deep  fascia  of,  341 

fascia  on  back  of,  388 
Foramen  chordae  anterius,  824 
posterius,  824 

caecum  of  medulla,  723 

Magendie,  716,  771 

Monro,  761 

ovale  of  heart,  200 

quadratum,  480 

Thebesius,  202 

Winslow,  462 
Fornix,  761 

conjunctive,  30,  793 

crura  of,  761 
Fossa,  ischio-rectal,  507 

Mohrenheim's,  64 

navicularis  of  labia,  521 

of  urethra,  557 

ovalis,  200 

scaphoidea  of  ear,  816 
Fourchette,  521 
Fourth  cranial  nerve,  17,  53,  749 

ventricle,  772 
Fovea  centralis  of  eye,  806 

hemi-elliptica,  825 

hemispherica,  825 

inferior,  773 

superior,  773 
Frsenuluin,  770 

labiorum,  521 
Frontal  artery,  4,  59 

•nerve,  52 


Galactophorous  ducts,  837 

Galen,  veins  of,  14,  765 

Gall-bladder,  582 
duct  of,  583 
fissure  for,  576 
relations  of,  455 
structure  of,  583 

Ganglion  of  Andersch,  144 


INDEX. 


859 


GAN 

Ganglion  (continued) 

Arnold,  146,  263 

Bochdalek,  260 

cardiac,  196 

cervical  inferior,  154 
middle,  153 
superior,  151 

diaphragmatic,  480 

Gasserian,  18 

geniculate  of  facial,  268 

impar,  150,  547 

jugular,  144,  265 

lenticular,  59 

Meckel's,  260 

ophthalmic,  59 

otic,  263 

petrous,  144,  265 

pneumogastric,  root  of,  146,  267 
trunk, 267 

semilunar,  477 

spheno-palatine,  260 

spirale,  828 

submaxillary,  105 

Wrisberg,  196 
Gasserian  ganglion,  18 
Gastrocnemius,  674 
Genito-crural  nerve,  497 
Gimbernat's  ligament,  427,  619 
Giraldes,  organ  of,  844 
Glands,  agminate,  603 

anal,  506 

Bartholin,  523 

Brunner's,  603 

buccal,  38 

coccygeal,  486 

Cowper's,  517 
•    Duverney's,  523 

Havers',  699 

lachrymal,  53 

Lieberkiihn,  603 

lingual,  256 

Littre,  537  . 

Luschka,  486 

Meibomian,  33 

molar,  38 

parotid,  41 

pineal,  769 

pituitary,  744 

prostate,  536 

sublingual,  104 

submaxillary,  94 

thyroid,  85 

tracheal,  218 

Tyson,  558 

uterine,  571 


IIEA 

Glands,  lymphatic  axillary,  314 

bronchial,  195 

elbow,  at,  328 

femoral,  611 

inguinal,  422,  611 

intercostal,  193 

lumbar,  481 

mediastinal,  anterior,  160 

neck,  deep,  89 

superficial,  67 

popliteal,  668 

submaxillary,  99 
Glandula  socia  parotidis,  43 
Glandule  concatenatas,  89 

Pacchionii,  10 
Glans  clitoridis,  522 

penis,  561 

Glisson's  capsule,  579 
Globus  major,  840 

minor,  840 

Glosso-epiglottic  folds,  244 
Glosso-pharyngeal  nerve,  143,  265,  752 
Glottidis  rima,  245 
Glottis,  245 

muscles  acting  on,  250 
Gluteal  region,  654 
Gluteus  maximus,  parts  seen  under,  655 

nerve,  inferior,  662 

superior,  546,  657 
Graafian  follicles,  574 
Groin,  dissection  of,  610 
Gubernaculum  testis,  846 
Gyri  operti,  742 
Gyrus  fornicatus,  741 


Hamstring  muscles,  671 
Hamulus  of  cochlea,  828 
Hand,  dissection  of  palm,  353 

surface  marking,  353 
Hasner,  valve  of,  275 
Havers,  gland  of,  699 
Heart  auricle,  left,  205 

right,  199 

cavities,  thickness  of,  212 
chordae  tendineas,  203 
endocardium,  200 
fibrous  rings  of,  209 
lymphatics  of,  208 
muscular  fibres  of,  211 
musculi  papillares,  203 
nerves  of,  195 
openings,  size  of,  207 


860 


INDEX. 


HBA 

Heart  (continued) 

position  of,  167,  198 
valves  of,  203 
veins  of,  208 
ventricles,  left,  206 

right,  202 
weight  of,  198 
Helicotrema,  827 
Helix,  816 

Henle,  looped  tubes  of,  in  kidney,  592 
Hepatic  artery,  467 

duct,  470 

Hernia,  congenital,  444 
encysted,  445 
femoral,  619 

coverings  of,  624 
seat  of  stricture,  625 
funicular,  445 
infantile,  445 
inguinal,  anatomy  of,  440 
changes  in  old,  446 
direct,  443 
oblique,  442 
position  of  cord  in,  446 
seat  of  stricture,  446 
tunica  vaginalis,  445 
lumbar,  447 
of  ovary,  521 
umbilical,  446 
ventral,  447 

Herophili,  torcular,  15,  721 
Hesselbach's  triangle,  443 
Hey's  ligament,  618 
Highmorianum,  corpus,  842 
Hilton's  muscle,  251 
Hip-joint,  movements  at,  700 
Hippocampus,  major,  764 

minor,  764 

Houston,  valves  of,  606 
Huguier,  canal  of,  824 
Humour,  aqueous,  812 

vitreous,  813 
Hunter's  canal,  637 
Hyaloid  membrane,  813 
Hydatids  of  Morgagni,  840 
Hymen,  522 

varieties  of,  522 
Hypogastric  plexus,  495 
Hypoglossi  ansa,  85,  110 
Hypoglossal  nerve,  20,  103,  150,  753 
HyoideS  os,  239 
basi-hyal,  239 
cerato-hyals,  239 
ligaments  of,  239 
thyro-hyals,  239 


IRI 

Ileo-csecal  valve,  605 

artery,  472 
Ileum,  course  of,  450 
Iliac  artery 

common,  490 

external,  492 

internal,  539 

ligature  of,  493 

fascia,  487 

veins,  543 
Iliacus,  489 
Ilio-costalis,  282 

lumbar  artery,  539 

tibial  band,  615 
Impressio  colica,  577 

renalis,  577 
Incisura  cerebelli  anterior,  776 

posterior,  776 
Incus,  822 

Infra-clavicular  triangle,  309 
Infundibuliform  fascia,  436 
Infundibulum  of  brain,  774 

cochlea,  827 

heart,  202 
Inguinal  region,  438 

glands,  611 

hernia,  440 

nerves,  423 
Infra-orbital  artery,  48,  136 

nerve,  47 
Innominate  artery,  178 

veins,  172 
Interarticular  nbro-cartilages 

(See  Fibro-cartilages) 
Intercarotic  ganglion,  486 
Intercolumnar  fascia,  427 
Intercostal  arteries,  190 
anterior,  159 
collateral,  191 
dorsal,  191 
superior,  122 

glands,  193 

muscles,  189 

nerves,  192 

Intercosto-humeral  nerves,  325 
Internal  ear,  824 
Interpleural  space,  162 
Intervertebral  fibre-cartilages,  296 
Intestine,  large,  course  of,  450 
relations  of,  453 
structure  of,  604 

small,  course  of,  450 
structure  of,  601 
Intumescentia  gangliformis,  268 
Iris,  802 


IXDEX. 


861 


IRI 

Iris  (continued) 

arteries  of,  804 

nerves  of,  805 

structure  of,  803 
Ischio-rectal  fascia,  528 

fossa,  507 

boundaries  of,  520 

Iter  a  tertio  ad  quartum  ventriculum, 
771 

ad  infundibulum  768 


Jacob's  membrane,  810 
Jacobson,  nerve  of,  266 
Jaw,  lower  ligaments  of,  142 
Jejunum,  course  of,  450 
Joints  (See  Articulations) 
Jugular  ganglion,  265 
vein,  anterior,  67 

external,  66 

internal,  84 

posterior  external,  67 


Kerkring,  valves  of,  601 
Kidneys,  589 

arteries  of,  484,  593 

capsule  of,  589 

cortical  structure  of,  589 

lymphatics  of,  595 

medullary  structure  of,  590 

nerves  of,  593 

pyramids  of,  590 

situation  of,  457 

tubuli  uriniferi,  592 

veins  of,  484,  595 
Knee-joint,  arteries  of,  677 

ligaments  of,  701 

movements  of  705 

nerves  of,  653 


Labia  majora,  521 

minora,  422 
Labial  arteries,  39 

nerves,  48 
Labium  cerebri,  754 

tympanicum,  828 

vestibulare,  828 
Labyrinth  of  ear,  824 
Lachrymal  gland,  54 

nerve,  53 

sac,  33,  274 

Lacunas  of  urethra,  557 
Lacus  lachrymalis,  30 


LIG 

Lamina,  anterior,  of  cornea,  798 
posterior  of  cornea,  799 
cinerea,  743 
cribrosa,  796 
fusca,  796 
spiralis,  828 

ossea,  828 

supra-choroidea,  800 
Laminated  tubercle  of  cerebellum,  776 
Lancisi,  nerves  of,  755 
Larynx,  238 

arteries,  251 
cartilages,  240 
male  and  female,  252 
mucous  membrane  of,  243 
muscles,  247 
nerves,  251 
situation  of,  238 
upper  opening  of,  244 
ventricle  of,  247 
Laryngotomy,  90 
Lateral  sinuses,  13 
ventricles,  756 
Latissimus  dorsi,  322,  370 
Lawrence  on  femoral  hernia,  624 
Leg,  dissection  of,  back,  672 

front,  643 

Lens,  crystalline,  814 
capsule  of,  814 
structure  of,  815 
suspensory  ligament  of,  814 
Lenticular  ganglion  59 
Lieberkuhn's  glands,  603,  605 
Ligamenta  alaria,  705 
annularia,  363 
vaginalia,  363 
Ligaments  of : 

accessory  of  shoulder,  406 
acromio-clavicular,  inferior,  404 

superior,  403 
ankle,  anterior,  707 

lateral  external,  708 

internal,  707 

annular  anterior  of  ankle,  646 
external  of  ankle,  646 
internal  of  ankle,  646 
carpus  anterior,  358 
radius,  409 
posterior  of  wrist,  389 
anterior  carpal,  413 
common,  295 
elbow,  409 
wrist,  413 

arcuate,  external,  478 
internal,  478 


862 


INDEX. 


LIG 

Ligaments  (continued) 

astragalo-scaphoid,  710 
atlo-axoid,  anterior,  300 

posterior,  300 
bladder,  false,  503,  526 

true,  529 
Burns',  618 
calcaneo-astragaloid,  external,  709 

interosseous,  709 

posterior,  709 
calcaneo-cuboid,  long,  711 

short,  711 

internal,  711 

superior,  711 
•carpo-metacarpal,  415 

dorsal,  415 

palmar,  415 

interosseous,  415 
carpus,  413 
central  of  cord,  785 
check,  299 
ciliary  of  eye,  802 
common,  anterior  vertebral,  295 

posterior  vertebral,  295 
conoid,  404 
coraco-acromial,  405 

clavicular,  404 
.    humeral,  406 
coracoid,  405 
coronary  of  knee,  704 

liver,  576 
costo-clavicular,  402 

sternal,  302 

transverse,  301 

vertebral,  300 
cotyloid,  699 
crico-arytenoid,  242 
crico-thyroid,  241 
crucial  of  knee,  703 
cruciata,  363 
cruciform,  300 
deltoid  of  ankle,  707 
elbow,  anterior  and  posterior,  409 

lateral  external,  409 

internal,  409 
falciform  o'f  Burns,  618 

liver,  455 

sacro-sciatic,  695 
femoral  (Key's),  618 
gastro-phrenic,  459 
•  Gimbernat's,  427,  619 
glenoid,  407 

of  fingers,  417 
Hey's,  618 
hip,  696 


LIG 

Ligaments  (contimied) 
hyo-epiglottic,  243 
hyoid  bone,  239 
ilio-femoral,  697 

lumbar,  693 
incus,  823 

interarticular  of  ribs,  301 
intercarpal,  414 
interclavicular,  401 
intermetatarsal,  713 
interosseous  of  cuneiform  bones,  712 
interosseous  of  forearm,  410 

leg,  707 

tarsus,  709 
interspinous,  295 
intertransverse,  298 
jaw,  303 
knee,  701 

latum  pulmonis,  160 
long  calcaneo-cuboid,  711 
lumbo-sacral,  693 
metacarpal,  416 
metacarpo-phalangeal,  417 
metatarsal,  713 
metatarso-phalangeal,  714 
mucosum  of  knee,  705 
malleus,  823 
nuchae,  297 
oblique  of  radius,  410 

sacro-iliac,  695 
occipito-atloid,  298 
occipito-axial,  299 
odontoid,  299 
orbicular  of  radius,  409 
ovary,  572 
palpebral,  32 
palmar,  363 
patella,  635 
phalangeal  of  hand,  418 

foot,  714 

plantar,  long,  711 
posterior,  common,  295 

of  Winslow,  670,  702 
Poupart's,  426,  619 
pterygo-maxillary,  36 
pubic,  696 

sub-pubic,  696 
pubo-femoral,  697 

prostatic,  529 
radio-carpal,  413 

ulnar,  711 
rhomboid,  402 
round,  of  hip,  698 

liver,  455 

radius,  410 


INDEX. 


863 


LIG 

Ligaments  (continued) 

uterus,  439,  504 
sacro-coccygeal,  694 
sacro-iliac  anterior,  694 

posterior,  695 

oblique,  695 
sacro-sciatic,  great,  695 

lesser,  696 
sacro-vertebral,  693 
scapulo-clavicular,  403 
shoulder-joint,  405 
stellate,  300 
sterno-clavicular,  401 
stylo-hyoid,  143 
stylo-maxillary,  70,  100 
subpubic,  696 
subflava,  296 
supraspinous,  296 
suspensory  of  lens,  814 

liver,  455 
penis,  558 

iarso-metatarsal,  713 
tarsus,  709 

temporo-maxillary,  303 
teres  of  hip,  698 
thyro-arytenoid  inferior,  246 

superior,  245 
thyro-epiglottic,  243 
thyro-hyoid,  239 
tibio-fibular  inferior,  707 

superior,  706 
transverse,  of  fingers,  355 

hip,  690 

knee,  704 

metacarpal,  398 

metatarsal,  713 
trapezoid,  404 
triangular  of  abdomen,  427 

perineum,  515 
uterus,  503 
Winslow,  670,  702 
wrist,  412 
Zinn,  61 

Ligamenta  subflava,  296 
Ligamentum  denticulatum,  785 
mucosum,  705 
nuchas,  297 
patellae,  701 
pectinatum  iridis,  799 
posticum  Winslowii,  702 
spirale,  828 
suspensorium,  300 
Ligula,  772 
Limbus  spiralis,  828 
Linea  alba,  432 


LUX 

Linea  (continued) 

semilunaris,  429 

splendens,  785 

transverse  of  fourth  ventricle,  772 

rectus,  431 
Lingua  frasnum,  253 

dorsalis  artery,  106 
Lingual  artery,  108 

glands,  256 

nerve,  104 
Lithotomy,  parts  divided  in,  516 

parts  to  be  avoided  in,  516 
Littre,  glands  of,  557 
Liver,  situation  of,  455 

arteries  of,  580 

cells  of,  581 

coats  of,  578 

ducts  of,  581 

fissures  of,  576 

functions  of,  582 

ligaments  of,  578 

lobes  of,  577 

lobules  of,  578 

lymphatics  of,  581 

nerves  of,  582 

plexus  of,  579 

structure  of,  578 

veins  of,  579 
Lobule  of  the  ear,  816 

paracentral,  737 
Lobulus  caudatus,  578 

centralis,  775 

quadratus,  578 

Spigelii,  577 
Locus  cteruleus,  773 

niger,  745 

perforates  anticus,  744 

posticus,  745 
Longitudinal  sinus,  inferior,  14 

superior,  11 
Lumbar  aponeurosis,  373 

arteries,  485 

fascia,  279 

hernia,  447 

plexus  of  nerves,  496 
Lumbricales  of  hand,  364 

foot,  687 
Lungs,  219 

air-cells  of,  223 

arteries  of,  224 

infundibula  of,  222 

lobes  of,  166 

lymphatics  of,  224 

nerves  of,  224 

position  and  form  of,  166 


864 


INDEX. 


LUX 

Lungs  (continued) 

root  of,  constituents,  197 

shape  of,  219 

structure  of,  216 

veins  of,  224 
Lunulas  of  valves,  205 
Luschka,  gland  of,  486 
Lymphatics,  heart,  208 

kidney,  595 

liver,  581 

lung,  224 

pancreas,  585 

parotid  gland,  43 

scalp,  8 

spleen,  588 

testis,  845 

uterus,  567 
Lymphatic  glands,  cervical  deep,  88 

superficial,  67 
Lyra  of  fornix,  762 


Macula  acustica,  833 

cribrosa,  825 

lutea,  806 

Magendie,  foramen  of,  716,  771 
Malleus,  822 

ligaments  of,  823 
Malpighi,  pyramids  of,  590 
Malpighian  bodies  of  kidney,  594 

'spleen,  587 
Mammary  gland,  836 

arteries  of,  837 

lymphatics  of,  837 

internal  artery,  122,  159 
Mammilla,  836 
Marginal  convolution,  742 
Marshall,  vestigial  fold  of,  201 
Maxillary  artery,  external,  38 

internal,  133 

nerve,  inferior,  19,  137 
superior,  19,  259 

vein,  137 
Meatus  auditorius  externus,  818 

of  the  nose,  273 

urinarius,  female,  523 
Meckel's  ganglion,  260 
Median  artery,  350 

nerve,  336 

in  palm,  361 

vein,  340 
Mediastinum,  162 

anterior,  163 

middle,  164 

posterior,  163,  181 


MES 

Mediastinum  (continued) 

superior,  164 
Medulla  oblongata,  722 
anterior  pyramid,  723 
fissures  of,  723 
lateral  tracts  of,  724 
nuclei  of,  728,  730 
olivary  bodies,  724 
fasciculus,  727 
posterior  pyramids,  726 
restiform  bodies,  725 
septum  of,  729 
Medulli-spinal  veins,  782 
Meibomian  glands,  33 
Meissner's  plexus  of  nerves,  604 
Membrana  basilaris,  828 
fusca,  796 

limitans  of  retina,  811 
nictitans,  30 
pupillaris,  803 
sacciformis,  412 
tectoria,  832 
tympani,  821 

arteries  of,  821 
flaccida,  821 
secundaria,  827 

Membrane,  of  aqueous  humour,  812 
arachnoid  of  brain,  715 

spinal  cord,  783 
Bruch,  801 
choroid,  800 
Corti,  830 
costo-coracoid,  309 
crico-thyroid,  241 
Demours,  799 
Descemet,  799 
hyaloid,  813 
interosseous  of  forearm,  410 

leg,  706 
Jacob's,  810 
Eeissner,  829 
thyro-hyoid,  239 
Schneiderian,  275 
Membranes  of  brain,  8,  715 

spinal  cord,  783 
Membranous  labyrinth,  832 
semicircular  canals,  832 
Meningeal  arteries,  16 
anterior,  16 
middle,  16,  134 
parva,  16 
posterior,  16,  107 
small,  135 
Mesenteric  artery,  inferior,  473 
superior,  472 


INDEX. 


865 


MES 

Mesenteric  veins,  inferior,  474 

superior,  470 
Mesentery,  462 
Meso-colon,  ascending,  463- 
descending,  463 
transverse,  462 
sigmoid,  463 
rectum,  463,  531 
Mesorchium,  848 
Metencephalon,  778 
Mitral  valves,  206 
Modiolus  of  cochlea,  827 
Mohrenheim's  fossa,  64 
Molar  glands,  38 
Monro,  foramen  of,  761 
Mons  Veneris,  521 
Monticulus  cerebelli,  775 
Morgagni,  sinus  of,  229 

hydatids  of,  840 
Morsus  diaboli,  572 
Motor  oculi  nerve,  60,  749 
Mouth,  muscles  of,  25 
Movements  of  spine,  298 
Miiller,  fibres  of,  806 
Multifidus  spinae,  286 
Muscles ': — 

abdominal  functions  of,  433 

nerves  of,  434 
abductor  hallucis,  685 

indicis,  399 
minimi  digiti  manus,  360 

pedis,  685 
pollicis,  358 
accelerator  urinre,  511 
accessorius      ad     sacro-lumbalem, 

283 

flexor,  686 

adductor  brevis  femoris,  631 
hallucis,  690 
longus,  629 
magnus,  632 
pollicis,  359 
anconeus,  393 
antitragicus,  817 
aryteno-epiglottideus,  249 
inferior,  251 
superior,  251 
arytenoideus,  249 
attollens  aurem,  3 
attrahens  aurem,  3 
azygos  uvulae,  235 
back  of,  278 
biceps  of  arm,  329 

thigh,  669 
bi venter  cervicis,  285 


MUS 

Muscles  (continued) 

brachialis  antieus,  331 
buccinator,  36 
cervicalis  ascendens,  283 
ciliary,  802 
coccygeus,  538 
eoehlearis,  828 
eomplexus,  285 
compressor  naris,  34 

sacculi  laryngis,  251 

urethrffi,  517 

in  the  female,  524 
coraeo-brachialis,  331 
corrugator  supercilii,  30 
eremaster,  429 
crico-arytenoideus  lateralis,  249 

posticus,  248 
crico-thyroideus,  247 
crureus,  634 
dartos,  838 
deltoid,  379 
depressor  alee  nasi,  35 

anguli  oris,  27 

labii  inferioris,  27 
diaphragm,  477 
digastricus,  92 
dilatator  naris  anterior,  35 

posterior,  35 
ejaculator  urinae,  511 
erector  clitoridis,  521 

penis,  512 

spins,  281 

external  sphincter  ani,  508 
extensor  brevis  digitorum,  650 

carpi  radialis  brevior,  390 
longior,  390 

carpi  ulnaris,  392 

communis  digitorum,  391 

indicis,  394 

longus  digitorum  pedis,  647 

minimi  digiti,  392 

ossis  met.  pollicis,  393 

primi  internodii  pollicis,  394 

secundi  internodii  pollicis,  394 

proprius  hallucis,  649 
flexor  accessorius,  686 

brevis  digitorum,  685 
hallucis,  690 
minimi  digiti  manus,  360 

pedis,  691 
pollicis,  359 

carpi  radialis,  342 
ulnaris,  344 

longus  digitorum  pedis,  669 

pollicis,  351 

3K 


866 


INDEX. 


MUS 

Muscles  (continued) 

profundus  digitorum,  351 

proprius  hallucis,  679 

sublimis  digitorum,  344 
gastrocnemius,  674 
gemellus  inferior,  659 

superior,  659 
genio-hyoglossus,  102 

hyoideus,  101 
gluteus  maximus,  655 

medius,  656 

minimus,  657 
gracilis,  629 
helicis  major,  817 

minor,  817 
hyoglossus,  101 
iliacus,  489 
ilio-costalis,  282 
indicator,  394 
inferior    constrictor     of    pharynx, 

228 

infra-spinatus,  382 
intercostal,  external,  189 

internal,  190 
interosseous  of  foot,  692 

of  hand,  399 
interspinales,  287 
intertransversales,  287 
ischio-cavernosus,  512 
kerato-cricoid,  248 
latissimus  dorsi,  322,  370 
laxator  tympani,  823 
levator  anguli  oris,  36 
scapulae,  374 

ani,  538 
female,  563 

labii  inferioris,  27 

superioris  alaeque  nasi,  35 
proprius,  35 

menti,  27 

palati,  234 

palpebrse,  32,  54 

prostatse,  538 
levatores  costarum,  287 
lingualis,  inferior,  257 

superficial,  257 
longissimus  dorsi,  283 
longus  colli,  293 
lumbricales  manus,  364 

pedis,  687 
masseter,  129 
of  mastication,  129 
middle  constrictor  of  pharynx,  228 
„  mouth,  25 
multindus  spiase,  286 


MUS 

Muscles  (continued) 
mylo-hyoideus,  99 
nose,  of  the,  34 
obliquus  auris,  818 

externus  abdoniinis,  425 

inferior  oculi,  62 
capitis,  289 

internus  abdominis,  428 

superior  oculi,  55 

capitis,  289 
obturator  externus,  660 

internus,  658 
occipito-frontalis,  2 
opponens  digiti  manus,  360 

pollicis,  359 
orbicularis  oris,  25 

palpebrarum,  28 
omo-hyoid,  79,  375 
palato-glossus,  235 

pharyngeus,  235 
palmaris  brevis,  354 

longus,  344 
pectineus,  629 
pectoralis  major,  308 

minor,  314 
peroneus  brevis,  652 

longus,  651,  693 

tertius,  648 
plantaris,  674 
platysnia  myoides,  64 
popliteus,  678 
prevertebral,  293 
pronator  quadratus,  352 

radii  teres,  342 
psoas  magnus,  488 

parvus,  489 
pterygoideus  externus,  131 

internus,  132 
pyramidalis,  432 

nasi,  34 
pyriformis,  658 
quadratus  femoris,  659 

lumborum,  490 

menti,  27 

quadriceps  femoris,  633 
recti  of  the  eye,  61 
rectus  abdominis,  431 

capitis  anticus  major,  294 
minor,  294 

lateralis,  289 

posticus  major,  288 
minor,  289 

externus  oculi,  61 

femoris,  633 

internus  oculi,  61 


INDEX. 


8G7 


MUS 

Muscles  (continued) 

rectus  inferior  oculi,  61 

sternalis,  307 

superior  oculi,  55 
retrahens  aurem,  3 
rhomboideus  major,  374 

minor,  374 
risorius,  25 
rotatores  spins,  286 
sacro-lumbalis,  282 
sartorius,  626 
scalenus  anticus,  111 

medius,  111 

posticus,  111 
serni-mernbranosus,  670 
semi-spinalis  colli,  286 

dorsi,  285 

semi-tendinosus,  669 
serratus  magnus,  323,  377 

posticus  inferior,  278 

superior,  278 
soleus,  675 
sphincter  ani  internus,  531 

iridis,  804 

vaginae,  525 

vesicle,  548 
spinalis  dorsi,  284 
splenius  capitis,  281 

colli,  281 
stapedius,  823 
sterno-cleido  mastoideus,  71 

hyoid,  77 

thyroid,  77 
stylo-glossus,  103,  142 

hyoideus,  93 

pharyngeus,  142 
subanconeus,  386 
subclavius,  310 
subcostal,  190 
subcrureus,  635 
sublimis  digitorum,  344 
subscapularis,  323,  383 
superior   constrictor    of    pharynx, 

228 
supinator  radii  brevis,  395 

longus,  345 
supra-spinales,  287 
supra-spinatus,  383 
temporal,  130 
tensor  fascias  femoris,  632 

palati,  234 

tarsi,  34 

tympani,  823 
teres  major,  323,  382 

minor,  382 


NER 

Muscles  (continued) 

thyro-arytenoideus,  250 

epiglottideus,  251 

hyoid,  79 
tibialis  anticus,  647 

posticus,  680,  693 
trachelo-mastoid,  283 
tragicus  of  ear,  817 
transversalis  abdominis,  430 

colli,  283 

pedis,  692 

transverso-spinalis,  285 
transversus  anriculaa,  818 

perinei,  512 

deep,  513 
trapezius,  368 
triangularis  sterni,  158 
triceps  extensor  cubiti,  338,  385 

femoris,  634 
of  ureters,  551 
uvulae  azygos,  235 
vastus  externus,  634 

internus,  634 
zygomaticus  major,  28 

minor,  28 
Musculi  papillares,  203,  207 

pectinati,  200 
Musculo-spiral  nerve,  338 
Mylo-hyoid  artery,  135 

nerve,  99,  140 


Nabothi  ovula,  569 
Nasal  fossae,  posterior  openings,  232 
duct,  275 
muscles,  34 

Naso-lobular  nerve,  35,  56 
Nates  of  brain,  770 
Neck,  central  line  of,  89 
cutaneous  nerves  of,  67 
dissection  of,  63 
lymphatics  of,  67 
surface  marking  of,  64 
triangles  of,  72 
anterior,  76 
carotid  inferior,  76 
superior,  77 
digastric,  91 
posterior,  76 
submaxillary,  91 
supra-clavicular,  75 
Nerves : 

abducens  oculi,  60,  750 
accessory  obturator,  643 
acromial,  69,  307 


868 


INDEX. 


NER 

Nerves  (continued) 

anterior  crural,  498,  641 

cutaneous  of  abdomen,  423 
tibial,  653 
Arnold's,  147 
auditory,  751,  834 
auriculo-parotidean,  68 

temporal,  6,  128,  139 
auricular  branch  of  pneumogastric, 
147 

posterior,  6,  108 
axillary,  plexus  of,  320 
back,  cutaneous  of,  289 
Bell,  nerve  of,  126,  324 
brachial  plexus,  124,  320 
buccal  branch  of  facial,  47 
inferior  maxillary,  138 
calcaneo-plantar,  682 
cardiac  branch  of  pneumogastric, 

148,  187 

inferior,  154 

middle,  154 

superior,  153 

carotid  of  glosso-pharyngeal,  263 

spheno-palatine  ganglion,  263 
cervical,   acromial   branch   of,  69, 

307 

posterior  branches  of,  367 
superficial,  68 
plexus,  deep,  109 
cervico-facial,  46 
chorda-tympani,  141,  269,  824 
ciliary,  long,  56 
short,  60 

circumflex,  322,  381 
clavicular,  69,  307 
cochlear,  834 
coccygeal,  544 

posterior  branch  of,  368 
communicans  noni,  84,  110 
communicans  peronei,  653,  666 
cornea,  nerves  of,  799 
coronary  anterior,  196 
posterior,  196 
cranial,  exit  of,  16 

at  base  of  skull,  265 
origin  of,  746 

crural  branch  of  genito-crural,  615 
cutaneous  of  chest,  306 
forearm,  340 
neck,  67 
thigh,  614,  668 
external,  614 
internal,  614 
middle,  614 


NER 

Nerves  (continued) 

dental,  anterior,  260 
inferior,  140 
posterior,  259 
descendens  noni,  84 
dorsal,  192,  367 
penis,  520 

twelfth  cranial,  423,  434,  753 
dura  mater,  9 
eighth  cranial,  19 

origin  of,  751 

eleventh  cranial,  20,  149,  752 
external    cutaneous,   of    musculo- 
spiral,  385 

of  peroneal,  645 

of  thigh,  498,  614 
laryngeal,  98 
plantar,  689 
popliteal,  652 

respiratory,  of  Bell,  126,  324 
saphenous,  667,  673 
superficial  petrosal,  24,  269 
facial,  6,  44 

cervical  branch  of,  69 

in  skull,  267 

origin  of,  750 
fifth  cranial,  18 

origin  of,  749 

sacral,  544 
first  cranial,  277,  747 

origin  of,  747 

lumbar,  496 
fourth  cranial,  17,  53 

pair,  origin  of,  749 

sacral,  544 
frontal,  5,  52 
genital   branch   of   genito  -  crural, 

497,  615 
genito-crural,  497 

crural  branch  of,  497,  615 
glosso-pharyngeal,  143,  265 

carotid  branches  of,  144 

lingual  branches  of,  144 

origin  of,  752 

pharyngeal  branches  of,  144 

tonsillar,  114 
gluteal,  inferior,  546,  657,  662 

superficial,  657 

superior,  657 
great  sciatic,  661,  665,  672 

occipital,  6,  290 
gustatory,  104,  140 
hypoglossal,  20,  103,  150 

origin  of,  753 
ilio-hypogastric,  414,  434,  496 


INDEX. 


869 


NER 

Nerves  (continued) 

ilio-inguinal,  424,  434,  496 

inguinal  branch  of,  G15 
incisor,  140 
inferior  dental,  140 

htumorrhoidal,  520 

laryngeal  or  recurrent,  187 

.maxillary,  19,  187 

pudendal,  509,  611 
infra-maxillary  of  facial,  47 

orbital  of  facial,  46 

of  superior  maxillary,  47 

trochlear,  56 
intercostal,  192 

abdominal,  193 

anterior  cutaneous   branches, 

307 
intercosto-humeral,  313,  325 

lateral  cutaneous  of,  307 

pectoral,  193 

internal  cutaneous,  of  arm,  325 
thigh,  614 

plantar,  G89 

popliteal,  666 

branches  of,  667 
interosseous  anterior,  353 
posterior,  396 
iris,  805 

Jacobson's  or  tympanic,  266 
labial,  48 
lachrymal,  53 
Lancisi,  755 
kidney,  595 
laryngoal,  external,  98,  148 

inferior,  148,  186,  252 

inferior  or  recurrent,  148,  187 

internal,  98,  148 

recurrent,  148,  187 

superior,  98,  148,  251 
lateral  cutaneous  of  abdomen,  423 
lesser  cutaneous  of  arm,  326 
lingual,  104,  140 

of  glosso-pharyngeal,  144 
long  or  inferior  pudendal,  509 
long  saphenous,  642 
liver,  582 
lumbar,  plexus  of,  496 

posterior  branches  of,  368 

sympathetic,  494 
lumbo-sacral,  544 
malar  branch  of  superior  maxillary, 

49,63 

malar  of  facial,  46 
maxillary  inferior,  137 
superior,  258 


NER 

Nerves  (continued) 
median,  336,  350 

cutaneous  branch  of,  351 

digital  branches  of,  361 

in  the  palm,  361 
mental,  49,  140 
masseteric,  138 
motor  oculi,  60 

origin  of,  749 

musculo-cutaneous,  of  arm,  337 
foot,  653 

spiral,  338,  341 
mylo-hyoid,  140 

hyoidean,  99 
nasal,  48,  56 

septal  branch  of,  66 

superior,  262 

upper,  262 
naso-lobular,  35,  49,  56 

palatine,  262 
neck,  cutaneous  of,  67 
nervi  molles,  40 
ninth  cranial,  20,  143 

origin  of,  752 

noni  communicantes,  84,  110 
obturator,  498,  642 

accessory,  498 

internus,  545 
occipital,  great,  6,  290 
small,  6,  68 
olfactory,  17,  277 

origin  of,  747 
ophthalmic,  19 
optic,  17,  67 

origin  of,  748 

orbital  branch  of  superior  maxillary, 
49,  63 

malar  branch  of,  49,  63 
palatine,  anterior,  262 

external,  262 

nasal  branches  of,  262 

naso-,  262 

posteiior,  262 
palpebral,  48 
palmar  branch  of  median,  354 

of  ulnar,  354 
pancreas,  585 
pars  intermedia,  751 
perinea!,  520 
peroneal,  652,  665 

external  cutaneous  branch  of, 

645 

pea  anserinus,  46 
petrosal,  external,  269 

great,  263 


870 


INDEX. 


NER 

Nerves  (continued) 

petrosal,  small  superficial,  266 
pharyngeal    of    glosso-pharyngeal, 
144 

of  pneumogastric,  147 
phrenic,  110,  112 

in  chest,  180 
plantar,  external,  688 

internal,  687 
pneumogastric,  20,  146,  186,  266 

auricular  branch  of,  6 

in  the  chest,  186 

course  of,  186 

origin  of,  752 
popliteal,  external,  652 

internal,  666 
portio  dura,  44 
posterior  auricular,  6,  45 

branches  of  spinal,  289 

interosseous,  396 

scapular,  375 

tibial,  682 

thoracic,  126,  324 
pterygoid,  138 

pudendal,  inferior  or  long,  509 
pudic,  520,  546 

pulmonary  branches    of    pneumo- 
gastric, 187 
radial,  347 
recurrent  or  inferior  laryngeal,  148, 

187 

rhomboid,  126 
sacral,  544 

fourth,  508 

plexus,  branches  of,  545 

posterior  branches  of,  368 
saphenous,  long,  642,  645 
scalp,  of,  4 
second  cranial,  17,  57 

origin  of,  748 

cervical,  271 
seventh  cranial,  6,  44,  267 

origin  of,  750 

shoulder,  cutaneous  of,  379 
sixth  cranial,  19,  60 

origin  of,  750 
small  occipital,  6,  68 

sciatic,  546,  662 

superficial  petrosal,  23 
in  sphenoidal  fissure,  22 
spheno-ethmoidal,  58 
spinal  accessory,  74,  140,  373 

origin  of,  752 

spinal,  posterior  branches  of,  367 
splanchnic,  great,  189 


NOS 

Nerves  (continued) 

splanchnic,  lesser,  189 

smallest,  189 
spleen,  588 
sternal,  68,  307 
subclavius,  125 
suboccipital,  271 

cutaneous  branch  of,  7 
subscapular,  321 
superior  gluteal,  546,  657 

maxillary,  19,  258 
supra-clavicular,  68,  306 

maxillary  branch  of  facial,  47 

orbital,  5,  47,  53 

scapular,  126,  376 

trochlear,  5,  47,  52 
sympathetic,  abdomen,  494 

cervical,  150 

in  the  chest,  188 

in  the  pelvis,  546 

temporal  branch  of  superior  max- 
illary, 6,  63 

deep  anterior,  138 
posterior,  138 

branches  of  facial,  6,  45 
temporo-facial,  6,  45 

malar,  6,  63 

tenth  cranial  nerve,  20,  146,  186, 
266 

origin  of,  752 
testis,  845 
third  cranial  nerve,  17,  60 

origin  of,  749 
thoracic  anterior,  311 

posterior,  126,  324 
tonsillar  of  glosso-pharyngeal,  144 
trifacial,  47,  138,  258 
trigeminal,  origin  of,  749 
trochlear,  of  orbit,  52,  56 
tympanic,  266,  269 
twelfth  cranial,  20,  103,  150 

origin  of,  753 
ulnar,  337,  349 

deep  palmar  branch  of,  366 

dorsal,  cutaneous  of,  350 

in  the  palm,  357 

deep,  366 
uterus,  567 
vestibular,  834 
Vidian,  263 
Wrisberg,  313,  326 
Nervi  molles,  40 
Nodule  of  cerebellum,  776 
Nose,  arteries  of,  40,  273,  276 
cartilages  of,  271 


INDEX. 


871 


NOS 

Nose  (continued) 

dissection  of,  271 

interior  of,  273 

meatus  of,  273 

mucous  membrane  of,  275 

muscles  of,  34 

nerves  of,  273,  277 

septum  of,  272 

veins  of,  276 
Niick,  canal  of,  505 
Nymphse,  522 


Obex,  772 

Obturator  artery,  541,  643 

abnormal,  541 
externus,  660 
fascia,  528 
internus,  658 
nerve,  498,  642 

accessory,  498,  643 
Obliquus  externus,  425 
inferior,  62,  289 
internus,  428 
superior,  55,  289 
Occipital  artery,  4,  107 
sinus,  15 
nerve,  great,  6,  290 

small,  6,  68 
vein,  4,  108 

Occipito-atloid  ligaments,  298 
axial  ligaments,  299 
frontalis,  2 

Odontoid  ligaments,  299 
Oculi  tendo,  28 

tutamina,  30 
CEsophageal  arteries,  194 

plexus,  187 
(Esophagus,  185 

structure  of,  186 
Olfactory  bulb,  17 

origin  of,  747 
nerves,  277 

Omentum,  gastro-colic,  463 
hepatic,  464 
splenic,  464 
great,  463 

cavity  of,  460 

lesser,  464  , 

Openings  for  aorta  in  diaphragm,  479 
cava,  vena,  in  diaphragm,  480 
cesophageal  in  diaphragm,  479 
of  heart,  207 
upper,  of  thorax,  157 
Operculum,  735 


PAN 

Ophthalmic  artery,  57 

ganglion,  59 

nerve,  19 

veins,  59 

Optic  nerve,  17,  57,  748 
Ora  serrata,  805 

structure  of,  812 
Orbit,  dissection  of,  49 

contents  of,  51 

fascia  of,  51 

nerves  at  back  of,  22 

periosteum  of,  50 
Organ  of  Corti,  830 

Giraldes,  844 
Kosenmuller,  575 
Ossicula  auditus,  821 

ligaments  of,  823 
Ostium  abdominale,  572 

externmm  of  uterus,  568 

internum  of  uterus,  568 

internum      of      Fallopian      tube, 

571 
Otic  ganglion,  263 

branches  of,  265 
Otoliths,  833 
Ovaries,  572 

arteries  of,  485 

position  of,  573 

structure  of,  573 
Oviducts,  571 
Ovula  of  Naboth,  569 
Ovum,  574 


Pacchionian  bodies,  10 
Palate,  glands  of,  237 

hard,  237 

pillars  of,  233 

soft,  232 

muscles  of,  234 
Palati  circumflexus,  234 

levator,  234 

tensor,  234 

velum  pendulum,  232 
Palatine  artery,  ascending,  98 

descending,  136 
Palmar  arch,  deep,  365 
superficial,  355 

profunda  artery,  365 
Palpebra,  30 

cartilages  of,  32 

conjunctiva  of,  30 
Pampiniform  plexus,  845 
Pancreas,  584 

duct  of,  585 


872 


INDEX. 


PAN 

Pancreas  (continued) 

functions  of,  585 

lesser,  584 

lymphatics  of,  585 

position  of,  457 

relations  of,  475 

structure  of,  585 

vessels  of,  585 
Papilla  lachrymalis,  30 
Papillas  circumvallatas,  254 

filiformes,  255 

fungiformes,  255 
Parepididymis,  844 
•JParotid  gland,  41 
dnct,  43 
relations  of,  42 
structure  of,  44 
structures  in,  42 
Parotidis  glandula  socia,  43 
Parovarium,  575 
Pars  ciliaris  retime,  806 
Pecquet,  cistern  of,  184 
Pectiniforme,  septum,  559 
Pedis  dorsal  artery,  650 
Pelvic  fascia,.  527 

female  viscera,  562 

male  viscera,  529 
Pelvis,  contents  of  female,  503 
male,  500 

side  view  of  female,  499 

male,  525 
Penis,  558 

bulb  of,  561 

artery  of,  519 

cervix  of,  558 

corona  glandis,  558 

corpus  eavernosum,  559 

artery  of,  519 
spongiosum,  561 

eras,  559 

dorsal  artery  of,  519 

erector,  512 

glans,  561 

glanclulse  Tysonii,  558 

helicine  arteries  of,  561 

lymphatics  of,  562 

nerves  of,  520,  562 

vessels  of,  562 

Perforating  arteries  of  thigh,  640 
Pericardium,  168 

objects  seen  on  opening,  170 

structure  of,  169 

vestigial  fold  of,  170 
Perilymph,  832 
Perineum,  female,  521 


PLA 

Perineum  (continued) 
male,  505 
boundaries  of,  505 
cutaneous  nerves  of,  508 
raphe  of,  506 
tendinous  centre  of,  509 
triangular  ligament  of,  515 
parts  between,  516 
surgery  of,  515 

Permeal  arteries,  superficial,  510 
fascia,  deep,  515 

superficial,  509 
transverse  muscle,  512 

deep  muscle,  513 
Peritoneum,  458 
course  of,  458 
lesser  cavity  of,  460 
parts  covered  by,  460 

partially  by,  460 
jmcovered  by,  460 
Peroneal  artery,  681 

anterior,  682 
nerve,  652,  665 
Pes  anserinus,  45 
Petit,  canal  of,  814 
Petrosal  ganglion,  265- 
nerve  lesser,  23,  263 

superficial  external,  24 
small,  266 
great,  23,  263 
sinuses,  inferior,  14 

superior,  14 
Peyer's  glands,  603 
Pharyngeal  aponeurosis,  226,  230 
artery,  ascending,  109,  145 
fascia,  226 
veins,  109 
venous  plexus,  227 
Pharynx,  224 

constrictors  of,  228 
mucous  membrane  of,  231 
openings  into,  230 
Phrenic  nerve,  110,  112 
in  chest,  180 
differences  of,  180 
Pia  mater  of  brain,  717 

spinal  cord,  784 
Pineal  body,  769 

peduncles  of,  769 
Pinna  of  ear,  816 

ligaments  of,  817 
structure  of,  816 
muscles  of,  817 
Pituitary  body,  744 
Plantar  artery,  external,  688 


INDEX. 


873 


PLA 

Plantar  artery,  internal,  687 

nerve,  external,  689 
internal,  689 

fascia,  684 
Plantaris,  674 
Platysma  myoides,  64 
Plexus  of  nerves,  Auerbach's,  604 

brachial,  124 

cardiac,  deep,  196 
superficial,  195 

carotid,  23,  151 

cavernous,  23,  152 

cervical,  superficial,  68 
deep,  110 

coeliac,  495 

coronary,  anterior,  196 
posterior,  196 

diaphragmatic,  494 

gastric,  495 

guise,  186 

hffimorrhoidal,  547 

hepatic,  495 

hypogastric,  495 

lumbar,  496 

Meissner's,  604 

mesenteric,  604 
inferior,  495 
superior,  495 

cesophageal,  187 

ovarian,  495 

patellar,  645 

pelvic,  546 

prostatic,  547 

renal,  495 

sacral,  544 

spermatic,  495 

splenic,  495 

superficial  cardiac,  195 

supra-renal,  495 

sympathetic  of  abdomen,  494 

uterine,  547 

vesical,  547 
of  veins,  interlobular,  579 

pampiniform,  845 

pterygoid,  137 

vaginal,  563 

vesico-prostatic,  529 
Pleura,  160 

outlines  of,  165 

cavity  of,  160 
Plica  semilunaris,  30 
Pneumogastric  nerve,  20,  146,  266,  752 
in  chest,  186 

ganglia  of,  267 

auricular  branch  of,  6 


PYR 

Pomum  Adami,  240 
Pons  hepatis,  576 

Tarini,  745 

Varolii,  731 
Popliteal  artery,  667,  676 

nerve,  external,  652 
internal,  666 

space,  664 

vein,  668,  678 
Popliteus,  678 
Porus  opticus,  796,  806 
Portal  fissure,  576 
Portio  dura,  44,  750 

mollis,  751 
Pouch  of  Douglas,  505 

recto -vaginal,  505 

vesical,  501 

Pouches,  laryngeal,  247 
Poupart's  ligament,  426,  619 
Precordial  region,  167 
Prepuce,  558 
Prevertebral  muscles,  293 

fascia,  70 

Processus  cochleariformis,  820 
Promontory  of  tympanum,  820 
Prosencephalon,  778 
Prostate,  536 

arteries  of,  554 

lobes  of,  551 

lymphatics  of,  554 

nerves  of,  554 

position  of,  536 

relations  of,  536 

sinus  of,  552 

structure  of,  553 

veins  of,  554 
Psoas  fascia,  487 

magnus,  488 

parvus,  489 
Pterygo-palatine  artery,  136 

maxillary  ligament,  36 

region,  131 

Pudendal,  inferior,  nerve,  509,  511 
Pudenda,  521 
Pudic  artery,  internal,  517,  542,  663 

nerve,  520,  546 
Pulmonary  artery,  194,  223 

nerves  of  pneurnogastric,  187 

valves,  204 
Pulmonis  hilum,  166 
Puncta  lachrymalia,  30,  33 
Pupil,  803 
Pylorus,  598 
Pyramid,     anterior,     of     tympanum, 

821 


874 


INDEX. 


PYR 


Pyramid  (continued) 

posterior,  of  tympanum,  820 
cerebellum,  776 


Quadratus  lumborum,  490 


Kadial  artery,  346 

at  back  of  wrist,  397 
in  palm  of  hand,  365 

nerve,  347 

vein,  340 
Ranine  artery,  106 

vein,  106 
Ranula,  142 

Eeceptaculum  chyli,  184,  481 
Recess,  lateral  of  fourth  ventricle,  772 
Recto-vaginal  pouch,  505 
Recto-vesical  fascia,  529 

pouch,  501 
Rectum,  604 

ampulla  of,  531 

arteries  of,  532 

course  of,  501 

digital  examination  of,  532 

folds  in,  606 

relations  of,  531 
Rectus  femoris,  633 
Region,  precordial,  167 
Regions  of  abdomen,  419 
Reil,  fillet  of,  727 

island  of,  735 

Reissner,  membrane  of,  830 
Restiform  bodies,  725 
Rete  testis,  842 
Retina,  805 

arteria  centralis  of,  58 

cones  and  rods  of,  810 

structure  of,  806 
Ribs,  movements  of,  303 
Rima  glottidis,  245 
Ring,  abdominal  external,  427 
internal,  436 

femoral,  623 

fibrous  of  heart,  209 
Rivini,  notch  of,  821 
Rivinus,  ducts  of,  104 
Rolando,  arciform  fibres  of,  726 

fissure  of,  735 

funiculus  of,  726 

tubercle  of,  726 
Rosenmiiller,  organ  of,  575 
Rugae  of  vagina,  564 
Ruyschiana  tunica,  801 


SEP 

Sac,  lachrymal,  33,  274 

of  omentum,  463 
Saccule  of  vestibule,  833 
Sacculus  laryngis,  247 
Sacro-lumbalis,  282 

iliac  articulation,  694 
Santorini,  cartilages  of,  242 

fissures  of,  817 
Saphena,  external  vein,  673 

internal  vein,  613 
Saphenous,  external  nerve,  667 

opening,  617 

posterior  vein,  673 
Scala  media,  828 

tympani,  828 

vestibuli,  828 
Scalp,  dissection  of,  1 

arteries  of,  4 

lymphatics  of,  8 

nerves  of,  4 

veins  of,  4 
Scaleni  muscles,  111 
Scapula  artery,  dorsalis,  318 
Scapular  artery,  posterior,  121,  376 
supra,  121,  384 

vein,  posterior,  121 
Scarpa,  liquor  of,  834 

triangle  of,  627 
Schlemm,  canal  of,  799 
Schneiderian  membrane,  275 
Sciatic  artery,  542,  662 

nerve,  great,  661,  665,  672 

small,  546,  662 
Sclerotic  coat  of  eye,  795 
structure  of,  796 
Scrotum,  838 

dartos  of,  838 

lymphatics  of,  839 

septum  of,  838 

vessels  of,  839 
Semicircular  canals,  826 
Semilunar  cartilages  of  knee,  703 

ganglia,  477 

valves,  204 

Semimembranosus,  670 
Semispinalis  colli,  826 

dorsi,  825 

Semitendinosus,  669 
Septum,  artery  of  nasal,  40 

auricularum,  200 

lucidum,  759 

pectiniforme,  559 

scroti,  838 

tongue,  258 

transversum,  833 


INDEX. 


875 


SEP 

Septum  (continued) 

ventriculorum,  202 
Serratus  magnus,  323,  377 

posticus  inferior,  278 

superior,  278 

Seventh  cranial  nerve,  19,  267,  750 
Sheath,  axillary  vessels,  309 

femoral  vessels,  621 

rectus  muscle,  432 
Sheaths  for  extensor,  tendons  of  hand, 

389 
Sheaths   for  flexor  tendons    of   hand, 

362 
Shoulder,  cutaneous  nerves  of,  378 

joint,  405 

movements  of,  407 

muscles  in  relation  with,  407 

synovial  membrane  of,  407 
Sigmoid  flexure  of  colon,  454 
Sinus  circularis  iridis,  799 

coronary,  208 

Morgagni,  229 

pocularis,  552 
.  prostaticus,  552 
Sinus  venous,  cavernous,  14,  21 

circular,  14 

coronary  of  heart,  201 

dura  mater,  10 

lateral,  13 

longitudinal,  inferior,  14 
superior,  11 

occipital,  15 

petrosal,  inferior,  14 
superior,  14 

straight,  14 

transverse,  15 

venosus,  199 
Sinuses,  great,  of  aorta,  176 

Valsalva,  176 

Sixth  cranial  nerve,  19,  60,  750 
Small  intestines,  601 
Socia  parotidis,  glandula,  43 
Scemmering,  foramen  of,  806 
Solar  plexus,  494 
Soleus,  675 
Space,  interpleural,  162 

popliteal,  664 

subdural,  8 
Spaces  of  Fontana,  799 

subarachnoid,  716 
Spermatic  cord,  439,  845 

arteries  of,  439,  484 

lymphatics  of,  439 

nerves  of,  439 

veins  of,  439 


STY 

Sphenoidal  fissure,  structures   passing 

through,  21 
Spheno-palatine  artery,  136 

ganglion,  260 

branches  of,  262 
Spigelii  lobulus,  577 
Spinse  rotatores,  286 
Spinal-accessory  nerve,  20,  74, 149,  373, 

752 
Spinal  cord,  786 

arteries  of,  791 

central  canal  of,  789 

fissures  of,  787 

functions  of,  791 

membranes  of,  783 

structure  of,  788 

Spinal  lateral  artery  from  vertebral,  120 
Spinal  nerves,  origin  of,  789 
Spine,  ligaments  of,  295 

movements  of,  298 
Splanchnic  nerves,  189 

great,  189 

lesser,  189 

smallest,  189 
Spleen,  585 

artery  of,  468,  587 

functions  of,  588 

lymphatics  of,  588 

Malpighian  corpuscles  of,  587 

nerves  of,  588 

omenta  of,  586 

pulp  of,  586 

relations  of,  456 

tunics  of,  586 

veins  of,  469,  588 
Splenium  of  corpus  callosum,  756 
Splenius  capitis,  281 

colli,  281 
Stapedius,  823 
Stapes,  822 
Stenson's  duct,  43 
Sterno-mastoid  muscle,  71 

artery,  middle,  96 
superior,  107 

parts  beneath,  80 
Stilling,  canal  of,  813 
Stomach,  596 

relations  of,  449 

structure  of,  599 
Straight  sinus,  14 
Striae  acusticse,  772 

laterales,  755 

longitudinales,  772 

medullares,  772 
Stylo-glossus,  103,  142 


876 


INDEX. 


STY 

Stylo-hyoid  ligament,  143 

muscle,  93 

Stylo-maxillary  ligament,  70,  100 
Subarachnoid  fluid  of  brain,  716 
of  spinal  cord,  784 

spaces  of,  716 
Subclavian  artery,  left,  115,  179 

right,  113 

ligature  of,  116 

vein,  123 
Subdural  space,  8 
Sublingual  artery,  106 

gland,  104 
Suboccipital  nerve,  7,  271 

triangle,  289 
Submaxillary  ganglion,  105 

gland,  94 

triangle,  91 
Subperitoneal  fat,  438 
Subscapular  artery,  317 

nerves,  321 

Subscapularis,  323,  383 
Sulci  of  brain,  733 
Sulcus  spiralis,  828 
Supercilii  corrugator,  329 
Supra-clavicular  nerves,  68 

triangle,  75 
Supra-renal  capsules,  595 

arteries  of,  596 

nerves  of,  596 

relations  of,  457 

structure  of,  596 
Supra-orbital  artery,  4,  58 

nerve,  5,  47,  53 
Supra-scapular  artery,  121,  375 

nerve,  126,  376 

vein,  121 

Supra-trochlear  nerve,  5,  47,  52 
Supra-spinales,  287 
Supra-spinous  ligament,  296 
Sylvius,  aqueduct  of,  771 

fissure  of,  734 
Sympathetic  nerves : 

cervical,  150,  153,  154 

cranial,  151 

lumbar,  494 

nervi  molles,  40 

pelvic,  546 

thoracic,  188 
Symphysis  pubis,  696 

sacro-iliac,  694 


Taenia,  fourth  ventricle,  772 
hippocampi,  762 


THY 

Tsenia  semicircularis,  764 

Tarsal  cartilages  and  ligaments,  32 

Tarsi,  tensor,  34 

Tarsus,  synovial  membranes  of,  712 

Tectorial  membrane,  832 

Tegmentum,  745 

Temporal  artery,  127 

superficial,  4 

deep,  128,  135 

fascia,  130     . 

muscle,  130 

nerves,  deep,  138 

veins,  128 

superficial,  4 
Temporo-facial  nerve,  45 
Temporo-maxillary  ligaments,  303 
Tendo  Achillis,  675 

palpebrarum,  28 
Tenon,  capsule  of,  51,  62,  794 
Tenth    cranial    nerve,    20,    146,    186, 

752 

Tentorium  cerebelli,  9 
Teres  major,  323,  382 

minor,  382 
Testes  cerebri,  770 

muliebres,  572 
Testis,  839 

arteries  of,  839 

coverings  of,  840 

descent  of,  846 

gubernaculum,  846 

lymphatics  of,  845 

mediastinum,  842 

nerves  of,  845 

structure  of,  843 
Thalamencephalon,  778 
Thalami  optici,  766 
Thebesii  foramina,  202 

valve,  201,  208 

veins  of,  208 
Theca  vertebralis,  783 
Third  cranial  nerve,  17,  60,  749 
Thoracic  aorta,  175 
Thoracic  artery,  alar,  317 
long,  317 
superior,  310 

nerves,  anterior,  311 

posterior,  126,  324 
Thoracic  duct,  184,  481 
Thoracico-acromialis  artery,  310 
Thorax,  base  of,  157 

dissection  of,  155 

osseous  measurements,  155 

upper  opening  of,  157 
Thymus  gland,  157 


INDEX. 


877 


THY 

Thyro-arytenoideus,  250 
Thyro-epiglottideus,  251 
Thyro-hyoid,  79 
Thyroid  artery,  superior,  96 
inferior,  120 

vein,  98 

cartilage,  240 

gland,  85 

arteries  of,  87 

lymphatics  of,  87 

nerves  of,  87 

structure  of,  87 

veins  of,  87 

Tibial  artery,  anterior,  649 
posterior,  681 

nerve,  anterior,  653 

posterior,  682 
Tibialis  anticus,  647 

posticus,  680 
Tomentum  cerebri,  717 
Tongue,  253 

arteries  of,  258 

foramen,  cfflcum  of,  253 

glands  beneath,  256 

mucous  membrane  of,  253 

muscular  fibres  of,  257 

nerves  of,  258 

papillae  of,  254 

raphe  of,  253 

septum  of,  258 
Tonsillar  artery,  98 
Tonsils,  235 
Torcular  Herophili,  15 
Trachea,  216 

cartilages  of,  217 

glands  of,  218 

mucous  membrane  of,  218 

muscular  fibres  of,  218 

relations  of,  216 
Tragus,  816 
Transversalis  fascia,  435 

abdominis,  430 

Trapezium  of  pons  Varolii,  732 
Trapezius,  368 
Triangle,  carotid  inferior,  76 
superior,  77 

digastric,  91 

elbow,  342 

Hesselbach's,  443 

infraclavicular,  309 

neck,  anterior,  76 
posterior,  73 

occipital,  73 

Scarpa's,  627 

subclavian,  75 


URE 

Triangle  (continued) 

submaxillary,  91 

suboccipital,  289 

supraclavicular,  75 
Triangular     ligament,     of     abdomen, 

427 

perineum,  515 
Triangularis  sterni,  158 
Triceps  extensor  cubiti,  338,  385 

femoris,  634 
Tricuspid  valves,  203 
Trifacial  nerve,  18,  749 
Trigonum  vesicse,  550 
Trochlea  of  orbit,  55 
Trochlearis  nerve,  17,  749 
Tube,  Eustachian,  236 

Fallopian,  571 
Tuber  annulare,  731 

cinereum,  744 

Tubercula  quadrigemina,  769 
Tuberculum  acusticum,  773 
Tubes,  bronchial,  217 
Tunica  albuginea,  841 

Euyschiana,  801 

vaginalis,  841 

vasculosa,  842 
Tutamina  oculi,  30 
Twelfth  cranial  nerve,  20,  103,  753 
Tympani  laxator,  823 

membrana,  821 

tensor,  823 
Tympanic  nerve  of  facial,  269 

glosso-pharyngeal,  266 
Tympanum,  819 

arteries  of,  824 
Tyson's  glands,  558 


Ulnar  artery,  348 
nerve,  337,  349 
in  palm,  357 
deep,  in  hand,  366 
veins,  340 

Umbilical  hernia,  446 
Umbilicus,  432 
Urachus,  447 
Ureter,  535 

course  of,  535 
muscles  of,  551 
orifices  of,  551 
Urethra,  female,  523 
male,  555 

bulbous  portion  of,  557 
fossa  navicularis  of,  557 
lacuna  of,  557 


878 


INDEX. 


URE 

Urethra  (continued] 

male,  membranous  part  of,  537 
spongy  part  of,  557 
structure  of,  557 
Uterus,  565 

arbor  vitro  of,  569 

arteries  of,  566 

cervix  of,  568 

glands  of,  571 

lymphatics  of,  567 

masculinus,  552 

nerves  of,  567 

os  of,  568 

position  of,  503 

round  ligament  of,  504 

structure  of,  567 

veins  of,  567 
Utricle  of  vestibule,  833 
Utriculus,  552 
Uvea,  803 
Uvula  of  bladder,  550 

cerebellum,  776 

palate,  233 
Uvula  azygos,  235 


Vagina,  525,  564 

arteries  of,  567 

bulb  of,  525 

structure  of,  564 

venous  plexus  of,  563 
Vagus  nerve,  20,  146,  186,  752 
Vallecula  of  cerebellum,  776 
Vallum  of  tongue,  254 
Valsalva,  sinuses  of,  176 
Valve,  coronary,  201 

Eustachian,  201 

Hasner,  275 

ileo-csecal,  606 

Kerkring,  601 

Thebesius,  201,  208 

Vieussens,  770 
Valves,  cardiac,  position  of,  171 

aortic,  207 

mitral,  206 

pulmonary,  204 

semilunar,  204 

tricuspid,  203 
Valvulse  conniventes,  601 
Varolii  pons,  731 
Vas  aberrans,  844 

deferens,  439,  535,  844 

spirale,  835 
Vastus  externus,  634 

internus,  634 


VEI 

Veins : 

angular,  41 
auricular,  108 
axillary,  319 
azygos,  left  upper,  183 

major,  182 

minor,  183 
basilic,  327 

median,  327 
basi-vertebral,  781 
brachial,  335 
brachio-cephalic,  172 
bronchial,  224 
capsular,  580 
cardiac,  anterior,  208 

great,  208 

posterior,  208 
cava,  inferior,  486 

superior,  173 
cephalic,  311,  327 

median,  327 
circumflex  iliac,  438 
coronary,  of  heart,  208 

of  stomach,  469 
dorsal  of  penis,  519 
dorsi-spinal,  781 
elbow  in  front  of,  327 
epigastric,  437 
facial.  40,  94 
femoral,  628 
frontal,  4 
of  Galen,  14,  765 
gastric,  469 

haemorrhoidal,  474,  529 
hepatic,  469,  580 
iliac,  common,  491 
external,  492 
internal,  529 
inferior  cava,  486 
innominate,  172 
intercostal,  superior,  183 
interlobular,  579 
intralobular,  579 
jugular  anterior,  67 

external,  66 

internal,  84 

posterior  external,  67 
kidney  of,  484 
lumbar,  486 
mammary  internal,  160 
maxillary  internal,  137 
median,  340 

deep,  340 

medulli-spinal,  782 
meningeal,  16 


INDEX. 


879 


VEI 

Veins  (continued) 

meningo-rachidian,  782 
mesenteric  inferior,  474 
superior,  473 
oblique,  of  Marshall,  201 
occipital,  4,  108 
ophthalmic,  59 
pharyngeal,  109 
phrenic,  484 
popliteal,  668,  678 
portal,  580 

profunda  femoris,  639 
pudic,  external,  613 

internal,  543 
pulmonary,  224 
radial,  346 
ranine,  106 
rectum,  532 
renal,  484,  595 
sacra  media,  486 
salvatella,  340 
saphenous  external,  673 
internal,  613 
scalp  of,  4 
scapular  posterior,  121 

supra,  121 
spermatic,  487,  845 
spinal  longitudinal  anterior,  781 
posterior,  782 
posterior  external,  780 
splenic,  469,  588 
subclavian,  123 
sublobular,  579 
supra-orbital,  4 

renal,  484 

scapular,  121 
temporal,  128 

superficial,  4 
Thebesii,  208 
thyroid  superior,  98 
tibial  posterior,  682 
tympanum  of,  824 
ulnar  anterior,  340 

posterior,  340 
umbilical,  213,  215 
uterine,  567 
vaginal,  567 

of  liver,  580 
vertebral,  120 
Velum  interpositum,  765 
medullary  anterior,  770 


ZYG 

Velum  (continued) 

medullary  posterior,  776 
pendulum  palati,  232 
Venae  vorticosse,  801 
Ventral  hernia,  447 
Ventricle  of  brain,  fifth,  760 
fourth,  771 
lateral,  756 
third,  767 
Ventricle  of  heart,  left,  206 

right,  202 

muscular  fibres  of,  211 
Ventricle  of  larynx,  247 
Vermiform  process,  inferior,  776 

superior,  775 
Vertebral  aponeurosis,  279,  373 

artery,  119,  719   ' 
Vincula  tendinum,  364 
Verumontanum,  552 
Vesico-prostatic  plexus,  529 
Vesicula  seminalis,  536 
structure  of,  554 
vessels  of,  554 
Vestibule  of  ear,  825 

vagina,  523 

Vestigial  fold  of  pericardium,  170 
Vibrissffi,  276 
Vidian  artery,  136 
nerve,  263 

Vieussens,  valve  of,  770 
Vitreous  body,  813 
Vocal  cords,  inferior  or  true,  246 
superior  or  false,  245 

Wharton's  duct,  141 
Willis,  circle  of,  720 

cords  of,  12 
Winslow,  foramen  of,  462 

posterior  ligament  of,  670 
Wirsung,  canal  of,  476,  585 
Wrisberg,  cartilages  of,  242 

ganglion  of,  196 

nerve  of,  326 
Wrist-joint,  synovial  membranes  of,  416 

triangular  fibro-cartilage  of,  411 

Zinn,  ligament  of,  61 

zone  of,  814 
Zygomaticus  major,  28 
minor,  28 


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FROM  PROF.  J.  M.  DACOSTA. 

"  1  find  it  an  excellent  work,  doing  credit  to  the  learning  an  i  discrimination  of  the  author." 

A  NEW  MEDICAL  DICTIONARY. 

A  compact,  concise  Vocabulary,  including 
all  the  Words  and  Phrases  used  in  medicine, 
with  their  proper  Pronunciation  and  Defini- 
tions. 

BASED  ON  RECENT  MEDICAL 
LITERATURE. 

BY 

GEORGE  M.  GOULD,  A.B.,  M.D., 

Ophthalmic  Surgeon  to  the  Philadelphia  Hospital,  Clinical 
Chief  Ophthtilmological  Dept.   German  Hos- 
pital, Philadelphia. 

It  is  not  a  mere  compilation  from  other 
dictionaries.  The  definitions  have  been 
made  by  the  aid  of  the  most  recent  stan- 
dard text-books  in  the  various  branches  of 

Plain  Dark  Leather,  without  Thumb  Index,    3.25    medicine.       It  includes 


Small   8vo,  Half  Morocco,  as  above,  with 

Thumb  Index, $4.25 


SEVERAL  THOUSAND  NEW  WORDS  NOT  CONTAINED  IN 
ANY  SIMILAR  WORK. 

IT  CONTAINS  TABLES  of  the  ABBREVIATIONS  used  in  Medicine,  of  the 
ARTERIES,  of  the  BACILLI,  giving  the  Name,  Habitat,  Character, sties,  etc.;  of  GAN- 
GLIA, LEUCOMAINES,  MICROCOCCI,  MUSCLES,  NERVES,  PLEXUSES, 
PTOMAINES,  with  the  Name,  Formula,  Physiological  Action,  etc.;  and  the  COMPARI- 
SON OF  THERMOMETERS,  of  all  the  most  used  WEIGHTS  AND  MEASURES 
of  the  world,  of  the  MINERAL  SPRINGS  OF  THE  U.  S.,  VITAL  STATISTICS, 
etc.  Much  of  the  material  thus  classified  is  not  obtainable  by  English  readers  in  any  other  work. 

OPINIONS  OF  PROMINENT  MEDICAL  TEACHERS. 


'•The  compact  size  of  this  dictionary,  its 
clear  type,  and  its  accuracy  are  unfailing 
pointers  to  its  coming  popularity." — John  B. 
Hamilton^  Supervising  Surgeon- General  U. 
S.  Marine  Hospital  Service,  Washington. 

"  It  is  certainly  as  convenient  and  as  useful  a 
volume  as  can  be  found,  regarding  contents  as 
well  as  arrangement." — Julius  Pohlman,  Prof, 
of  Physiology,  Medical  Dept.,  Univ.  of  Buffalo. 

"  I  have  examined  it  with  considerable  care, 
and  am  very  much  pleased  with  it.  It  is  a 
handy  book  for  reference,  and  so  far  as  I  have 
examined  it,  it  is  accurate  in  every  particular." 
— E.  H.  Bartley,  Prof,  of  Chemistry,  Long 
Island  College  Hospital,  Brooklyn. 

V I  consider  this  the  dictionary  of  all  others 
for  the  medical  student,  and  shall  see  that  it  is 
placed  on  our  list  of  text-books." — A.  R. 
Thomas,  M.D.,  Dean  Hahnemann  Medl.  Col., 
Philadelphia. 


"It  will  be  recommended  among  our  text- 
books in  our  new  catalogue."' — S.  £..  Chaille, 
M.D.,  Dean  Medl.  Dept.,  Tulane  Univ.,  New 
Orleans. 

"  Compact,  exact,  up  to  date,  and  the  tables 
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Cleveland, 

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reference  for  medical  students." — J.  W.  Hoi 
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Diagnosis,  Prognosis,  Surgery,  Therapeutics,  Toxicology,  Detection  of  Poisons 
by  their  appropriate  tests,  Hygiene,  etc.  By  GEORGE  ARMATAGE,  M.R.C.V.S. 
Second  Edition,  321110.  Boards,  $1.25 

BALLOT!.  Veterinary  Anatomy  and  Physiology.  By  WM.  R.  BALLOU,  M.D., 
Prof,  of  Equine  Anatomy,  New  York  College  of  Veterinary  Surgeons,  Physician 
to  Bellevue  Dispensary,  and  Lecturer  on  Genito-Urinary  Surgery,  New  York 
Poly  clinic,  etc.  With  29  Graphic  Illustrations.  I2mo.  No.  12  ?  Quis-Compend 
Series,  f  Cloth,  $1.00.  Interleaved,  for  the  addition  of  notes,  $1.25 

BAR.  Antiseptic  Midwifery.  The  Principles  of  Antiseptic  Methods  Applied  to 
Obstetric  Practice.  By  Dr.  PAUL  BAR,  Obstetrician  to,  formerly  Interne  in,  the 
Maternity  Hospital,  Paris.  Authorized  Translation  by  HENRY  D.  FRY,  M.D. 
with  an  Appendix  by  the  author.  Octavo.  Cloth,  $1.75 

BARNES.  Lectures  on  Obstetric  Operations,  including  the  Treatment  of  Hemor- 
rhage, and  forming  a  Guide  to  Difficult  Labor.  By  ROBERT  BARNES,  M.D. 
F.R.C.P.  Fourth  Edition.  Illustrated.  8vo.  Cloth,  $3.75 

BARRETT.  Dental  Surgery  for  General  Practitioners  and  Students  of  Medicine 
and  Dentistry.  Extraction  of  Teeth,  etc.  By  A.  W.  BARRETT,  M.D.  Second 
Edition.  Illustrated  Practical  Series.  {See  page  19 ^\  Cloth,  $1.25 

5 


6  P.  BLAKISTON,  SON  <S-  CO.'S 

BARTLEY.  Medical  Chemistry.  Second  Edition.  A  Text-book  for  Medical  and 
Pharmaceutical  Students.  By  E.  H.  BARTLEY,  M.D.,  Professor  of  Chemistry  and 
Toxicology  at  the  Long  Island  College  Hospital ;  President  of  the  American 
Society  of  Public  Analysts  ;  Chief  Chemist,  Board  of  Health,  of  Brooklyn.  N.Y. 
Revised  and  enlarged.  With  62  Illustrations.  Glossary  and  Complete  Index. 
423  pages.  I2mo.  Cloth,  $2.50 

BEALE.  On  Slight  Ailments ;  their  Nature  and  Treatment.  By  LIONEL  S.  BEALE, 
M.D.,  F.R.S.,  Professor  of  Practice,  King's  Medical  College,  London.  Second 
Edition.  Enlarged  and  Illustrated.  8vo.  Cloth,  $1.25 

Urinary  and  Renal  Diseases  and  Calculous  Disorders.    Hints  on  Diagnosis 
and  Treatment.     Demi-8vo.     356  pages.  Cloth,  $1.75 

The  Use  of  the  Microscope  in  Practical  Medicine.    For  Students  and 
Practitioners,  with  full  directions  for  examining  the  various  secretions,  etc., 
in   the  Microscope.     Fourth  Edition.     500  Illustrations.     8vo.     Cloth,  $7.50 
How  to  Work  with  the  Microscope.    A  Complete  Manual  of  Microscopical 
Manipulation,   containing   a  full   description   of  many   new   processes    of 
investigation,   with    directions    for    examining  objects   under  the    highest 
powers,  and  for  taking  photographs  of  microscopic  objects.     Fifth  Edition. 
Containing  over  400  Illustrations,  many  of  them  colored.     8vo.    Cloth,  $7.50 
One  Hundred  Urinary  Deposits,  on  eight  sheets,  for  the  Hospital,  Labora- 
tory, or  Surgery.     New  Edition.     4to.  Paper,  $2.00 
BEASLEY'S  Book  of  Prescriptions.     Containing  over  3100  Prescriptions,  collected 
from  the   Practice   of  the   most  Eminent  Physicians  and   Surgeons — English, 
French  and  American  ;  a  Compendious  History  of  the  Materia  Medica,  Lists  of 
the  Doses  of  all  Officinal  and  Established  Preparations,  and  an  Index  of  Diseases 
and  their  Remedies.     By  HENRY  BEASLEY.     Sixth  Edition.  Cloth,  $2.25 
Druggists'  General  Receipt  Book.     Comprising  a  copious  Veterinary  Formu- 
lary ;  Recipes  in  Patent  and  Proprietary  Medicines,  Druggists'  Nostrums, 
etc.;    Perfumery  and  Cosmetics  ;  Beverages,   Dietetic  Articles  and  Condi- 
ments ;  Trade  Chemicals,  Scientific  Processes,  and  an  Appendix  of  Useful 
Tables.     Ninth  Edition.     Revised.  Cloth,  $2.25 
Pocket  Formulary  and  Synopsis  of  the  British  and  Foreign  Pharmacopoeias. 
Comprising  Standard  and  Approved  Formulae  for  the   Preparations   and 
Compounds  Employed  in  Medical  Practice.    Eleventh  Edition.    Cloth,  $2.25 

BIDDLE'S  Materia  Medica  and  Therapeutics.  Eleventh  Edition.  For  the  Use  of 
Students  and  Physicians.  By  Prof.  JOHN  B.  BIDDLE,  M.D.,  Professor  of  Materia 
Medica  in  Jefferson  Medical  College,  Philadelphia.  The  Eleventh  Edition,  thor- 
oughly revised,  and  in  many  parts  rewritten,  by  his  son,  CLEMENT  BIDDLE,  M.D., 
Assistant  Surgeon,  U.  S.  Navy,  and  HENRY  MORRIS,  M.D.,  Demonstrator  of 
Obstetrics  in  Jefferson  Medical  College,  Fellow  of  the  College  of  Physicians,  of 
Philadelphia,  etc.  Cloth,  $4.25;  Sheep,  $5.00 

BLACK.  Micro-Organisms.  The  Formation  of  Poisons  by  Micro-Organisms.  A 
Biological  study  of  the  Germ  Theory  of  Disease.  By  G.  V.  BLACK,  M.D.,  D.D.S. 

Cloth,  £1.50 

BLODGETT'S  Dental  Pathology.  By  ALBERT  N.  BLODGETT,  M.D.,  Late  Profes- 
sor of  Pathology  and  Therapeutics,  Boston  Dental  College.  33  Illustrations. 
I2mo.  Cloth,  $1.75 

BLOXAM.  Chemistry,  Inorganic  and  Organic.  With  Experiments.  By 
CHARLES  L.  BLOXAM.  Edited  by  J.  M.  THOMPSON,  Professor  of  Chemistry  in 
King's  College,  London,  and  A.  G.  BLOXAM,  Dem.  of  Chem.,  Royal  Agricultural 
College,  Cirencester.  Seventh  Edition.  Revised  and  Enlarged.  With  330 
Engravings.  8vo.  Cloth,  $4.50;  Leather,  $5.50 

BOWLBY.    Injuries  and  Diseases  of  the  Nerves,  and  their  surgical  treatment. 

By  ANTHONY  A.  BOWLBY,   F.R.C.S.,  Surgical  Registrar  and   Demonstrator  of 

Practical  Surgery  at  St.  Bartholomew's  Hospital.     Illustrated  by  4  Colored  and 

20  other  full-page  plates.     8vo.  Cloth,  $4.50 

Surgical  Pathology  and  Morbid  Anatomy.     135  Illustrations.  Cloth,  $2.00 


MEDICAL  AND  SCIENTIFIC  PUBLICATIONS.  7 

BOWMAN.  Practical  Chemistry,  including  analysis,  with  about  100  Illustrations. 
By  Prof.  JOHN  E.  BOWMAN.  Eighth  English  Edition.  Revised  by  Prof.  BLOXAM, 
Professor  of  Chemistry,  King's  College,  London.  Cloth,  $2.00 

BRUBAKER.  Physiology.  A  Compend  of  Physiology,  specially  adapted  for  the 
use  of  Students  and  Physicians.  By  A.  P.  BRUBAKER,  M.D.,  Demonstrator  of 
Physiology  at  Jefferson  Medical  College,  Prof,  of  Physiology,  Penn'a  College  of 
Dental  Surgery,  Philadelphia.  Fifth  Edition.  Revised,  Enlarged  and  Illus- 
trated. No.  4,  f  Quiz- Compend  Series?  i2mo.  Cloth,  $1.00 

Interleaved  for  the  addition  of  notes,  $1.25 

BUCKNILL  AND  TUKE'S  Manual  of  Psychological  Medicine :  containing 
the  Lunacy  Laws,  the  Nosology,  Etiology,  Statistics,  Description,  Diagnosis, 
Pathology  (including  morbid  Histology)  and  Treatment  of  Insanity.  By  JOHN 
CHARLES  BUCKNILL,  M.D.,  F.R.S.,  and  DANIEL  HACK  TUKE,  M.D.,  F.R.C.T. 
Fourth  Edition.  Numerous  illustrations.  8vo.  Cloth,  $8.00 

BULKLEY.  The  Skin  in  Health  and  Disease.  By  L.  DUNCAN  BULKLEY,  M.D., 
Attending  Physician  at  the  New  York  Hospital.  Illustrated.  Cloth,  .50 

BTJXTON.  On  Anesthetics.  A  Manual.  By  DUDLEY  WILMOT  BUXTON,  M.R.C.S., 
M.R.C.P.,  Asst.  to  Prof,  of  Med.,  and  Administrator  of  Anaesthetics,  University 
College  Hospital,  London.  Practical  Series.  \_Seepage  IQ.~]  Cloth,  $1.25 

BURNETT.  Hearing,  and  How  to  Keep  It.  By  CHAS.  H.  BURNETT,  M.D.,  Prof, 
of  Diseases  of  the  Ear,  at  the  Philadelphia  Polyclinic.  Illustrated.  Cloth.  .50 

BYFORD.  Diseases  of  Women.  The  Practice  of  Medicine  and  Surgery,  as 
applied  to  the  Diseases  and  Accidents  Incident  to  Women.  By  W.  H.  BYFORD, 
A.M.,  M.D.,  Professor  of  Gynaecology  in  Rush  Medical  College  and  of  Obstetrics 
in  the  Woman's  Medical  College ;  Surgeon  to  the  Woman's  Hospital ;  Ex-Presi- 
dent American  Gynaecological  Society,  etc.,  and  HENRY  T.  BYFORD,  M.D.,  Sur- 
geon to  the  Woman's  Hospital  of  Chicago ;  Gynaecologist  to  St.  Luke's  Hos- 
pital ;  President  Chicago  Gynaecological  Society,  etc.  Fourth  Edition.  Revised, 
Rewritten  and  Enlarged.  With  306  Illustrations,  over  100  of  which  are  original. 
Octavo.  832  pages.  Cloth,  $5.00;  Leather,  $6.00 

On  the. Uterus.  Chronic  Inflammation  and  Displacement.  Cloth,  $1.25 

CAIRD  and  CATHCART.  Surgical  Handbook  for  the  use  of  Practitioners  and 
Students.  By  F.  MITCHELL  CAIRO,  M.B.,  F.R.C.S.,  and  C.  WALKER  CATHCART, 
M.B.,  F.R.C.S.,  Asst.  Surgeons  Royal  Infirmary.  With  over  200  Illustrations. 
32010.  400  pages.  Pocket  size.  Leather  covers,  $2.50 

CAMERON.  Oils  and  Varnishes.  A  Practical  Handbook,  by  JAMES  CAMERON, 
F.I.C.  With  Illustrations,  Formulas,  Tables,  etc.  I2mo.  Cloth,  $2.50 

Soap  and  Candles.  A  New  Handbook  for  Manufacturers,  Chemists,  Ana- 
lysts, etc.  Compiled  from  all  reliable  and  recent  sources.  54  Illustrations. 
I2mo.  Cloth,  $2.25 

CARPENTER.  The  Microscope  and  Its  Revelations.  By  W.  B.  CARPENTER, 
M.D.,  F.R.S.  Seventh  Edition.  Revised  and  Enlarged,  with  over  500  Illustra- 
tions and  Lithographs.  New  Edition  in  Prest. 

CAZEAUX  and  TARNIER'S  Midwifery.  With  Appendix,  by  Munde.  Eighth 
Revised  and  Enlarged  Edition.  With  Colored  Plates  and  numerous  other 
Illustrations.  The  Theory  and  Practice  of  Obstetrics  ;  including  the  Diseases 
of  Pregnancy  and  Parturition,  Obstetrical  Operations,  etc.  By  P.  CAZEAUX, 
Member  of  the  Imperial  Academy  of  Medicine,  Adjunct  Professor  in  the  Faculty 
of  Medicine  in  Paris.  Remodeled  and  rearranged,  with  revisions  and  additions, 
by  S.  TARNIER,  M.D.,  Professor  of  Obstetrics  and  Diseases  of  Women  and 
Children  in  the  Faculty  of  Medicine  of  Paris.  Eighth  American,  from  the 
Eighth  French  and  First  Italian  Edition.  Edited  and  Enlarged  by  ROBERT 
J.  HESS,  M.D.,  Physician  to  the  Northern  Dispensary,  Phila.,  etc.,  with  an  Ap- 
pendix by  PAUL  F.  MUNDE,  M.D.,  Professor  of  Gynaecology  at  the  New  York 
Polyclinic,  and  at  Dartmouth  College ;  Vice-President  American  Gynaecological 
Society,  etc.  Illustrated  by  Chromo-Lithographs,  Lithographs,  and  other  Full- 
page  Plates,  seven  of  which  are  beautifully  colored,  and  numerous  Wood  En- 
gravings. Students'  Edition.  One  Vol.,  8vo.  Cloth,  #5.00;  Full  Leather,  $6.00 


P.  BLAKISTON,  SON  &-  CO.'S 


CHAVASSE.    The  Mental  Culture  and  Training  of  Children.         Cloth,  $1.00 

CHURCHILL.  Face  and  Foot  Deformities.  By  FRED.  CHURCHILL,  M.D., 
Ass't  Surgeon  to  the  Victoria  Hospital  for  Sick  Children,  London.  Six  Plain 
and  Two  Colored  Lithographs.  8vo.  Cloth,  $3.50 

CLEVELAND'S  Pocket  Dictionary.  A  Pronouncing  Medical  Lexicon,  containing 
correct  Pronunciation  and  Definition  of  terms  used  in  medicine  and  the  col- 
lateral sciences,  abbreviations  used  in  prescriptions,  list  of  poisons,  their  anti- 
dotes, etc.  By  C.  H.  CLEVELAND,  M.D.  Thirty-third  Edition.  Very  small 
pocket  size.  Cloth,  .75;  Tucks  with  Pocket,  $1.00 

COHEN  on  Inhalation,  its  Therapeutics  and  Practice,  including  a  Description  of 

the  Apparatus  Employed,  etc.     By  J.  SOLIS-COHEN,  M.D.  Cl.,  $1.25 

The  Throat  and  Voice.    Illustrated.    i2mo.  Cloth,  .50 

COLLIE,  On  Fevers.  A  Practical  Treatise  on  Fevers,  Their  History,  Etiology, 
Diagnosis,  Prognosis  and  Treatment.  By  ALEXANDER  COLLIE,  M.D.,  M.R.C.P., 
Lond.  With  Colored  Plates.  Practical  Series.  See  Page  ig.  Cloth,  $2.50 

COOPER  on  Syphilis  and  Pseudo-Syphilis.  By  ALFRED  COOPER,  F.R.C.S.,  Sur- 
geon to  West  London  Hospital.  Octavo.  Cloth,  $3.50 

CROOKSHANK.  History  and  Pathology  of  Vaccination.  In  two  volumes. 
Vol.  I,  a  Critical  Inquiry.  Vol.  II  (Edited),  Selected  Essays.  By  EDGAR  M. 
CROOKSHANK,  M.B.,  Professor  of  Comparative  Pathology  and  Bacteriology  in 
King's  College,  London  ;  Author  of  a  "  Manual  of  Bacteriology,"  etc.  With  22 
Colored  Plates,  Fac-simile  Letters,  etc.,  and  other  Illustrations.  Royal  8vo. 
Over  noo  pages.  Handsome  Cloth,  Gilt  Top,  $8.50 

CROCKER.  Diseases  of  the  Skin.  Their  Description,  Pathology,  Diagnosis  and 
Treatment.  By  H.  RADCLIFFE  CROCKER,  M.D.,  Physician  to  the  Dept.  of  Skin 
Dis.  University  College  Hospital,  London.  With  Illustrations.  Cloth,  $5.50 

CULLINGWORTH.   A  Manual  of  Nursing,  Medical  and  Surgical.    By  CHARLES 

J.  CULLINGWORTH,   M.D.,   Physician  to  St.  Thomas'  Hospital,  London.     Third 

Revised  Edition.     With  18  Illustrations.     I2mo.  Cloth,  .75 

A  Manual  for  Monthly  Nurses.    Third  Edition.    321110.  Cloth,  .50 

DAVIS.  Biology.  An  Elementary  Treatise.  By  J.  R.  AINSWORTH  DAVIS,  of 
University  College,  Aberystwyth,  Wales.  Thoroughly  Illustrated.  I2mo.  #4.00 

DAVIS.    Clinical  Obstetrical  Chart.    Designed  by  ED.  P.  DAVIS,  M.D.,  and  J.  P. 
CROZER  GRIFFITH,  M.D.   Sample  copies  free.     Put  up  in  loose  packages  of  50,  .50 
Price  to  Hospitals,  500  copies,  $4.00;  1000  copies,  $7.50.     With  name  of  Hos- 
pital printed  on,  50  cents  extra. 

DAY.     Diseases  of  Children.    A  Practical  and  Systematic  Treatise  for  Practitioners 

and  Students.     By  WM.  H.  DAY,  M.D.     Second  Edition.     Rewritten  and  very 

much  Enlarged.     8vo.     752  pp.     Price  reduced.  Cloth,  $3.00 ;  Sheep,  $4.00 

On  Headaches.     The  Nature,  Causes  and  Treatment  of  Headaches.     Fourth 

Edition.     Illustrated.     8vo.  Paper,  .75;  Cloth,  $1.25 

DERMATOLOGY,  Journal  of.  Edited  by  MALCOLM  MORRIS,  M.R.C.S.  London, 
and  D.  G.  BROOKE,  M.R.C.S.  Manchester,  Eng.  Monthly.  Per  Annum,  $3.00 

DILLNBERGER.  On  Women  and  Children.  The  Treatment  of  the  Diseases  Pecu- 
liar to  Women  and  Children.  By  Dr.  EMIL  DILLNBERGER.  i2mo.  Cloth,  $1.50 

DOMVILLE.  Manual  for  Nurses  and  others  engaged  in  attending  to  the  sick.  By 
ED.  J.  DOMVILLE,  M.D.  Sixth  Ed.  With  Becipes  for  Sick-room  Cookery,  etc. 

Cloth,  .75 

DORAN.  Gynaecological  Operations.  A  Handbook.  By  ALBAN  DORAN,  F.R.C.S., 
Asst.  Surg.  to  the  Samaritan  Free  Hospital  for  Women  and  Children,  London. 
166  Illustrations.  8vo.  Cloth,  $4.50 

DUCKWORTH.  On  Gout.  Illustrated.  A  treatise  on  Gout.  By  SIR  DYCE 
DUCKWORTH,  M.D.  (Edin.),  F.R.C.P.,  Physician  to,  and  Lecturer  on  Clinical 
Medicine  at,  St.  Bartholomew's  Hospital,  London.  With  Chromo-lithographs 
and  Engravings.  Octavo.  Cloth,  $7.00 


MEDICAL  AND  SCIENTIFIC  PUBLICA  TIONS.  9 

DULLES.  What  to  Do  First,  In  Accidents  and  Poisoning.  By  C.  W.  DULLES,  M.D. 
Third  Edition,  Enlarged,  with  new  Illustrations.  Cloth.  .75 

DTJRKEE,  On  Gonorrhoea  and  Syphilis.  By  SILAS  DURKEE,  M.D.  Sixth  Edition. 
Revised  and  Enlarged,  with  Portrait  and  Eight  Colored  Illustrations.  Cloth,  $3.50 

EDIS.  Sterility  in  Women.  By  A.  W.  EDIS,  M.D.,  F.R.C.P.,  late  President  British 
Gynaecological  Society;  Senior  Physician,  Chelsea  Hospital  for  Women;  Physician 
to  British  Lying-in  Hospital,  etc.  Illustrated.  8vo.  Cloth,  $1.75 

EDWARDS.     Blight's    Disease.     How  a  Person  Affected  with  Bright's  Disease 

Ought  to  Live.     By  Jos.  F.  EDWARDS,  M.D.     2d  Ed.     Reduced  to        Cloth,  .50 

Vaccination  and  Smallpox.     Showing  the  Reasons  in  favor  of  Vaccination, 

and  the  Fallacy  of  the  Arguments  advanced  against  it,  with  Hints  on  the 

Management  and  Care  of  Smallpox  patients.  Cloth,  .50 

FAGGE.  The  Principles  and  Practice  of  Medicine.  By  C.  HILTON  FAGGE,  M.D., 
F.R.C.P.,  F  R.M.C.S.,  Examiner  in  Medicine,  University  of  London  ;  Physician  to, 
and  Lecturer  on  Pathology  in,  Guy's  Hospital ;  Senior  Physician  to  Evelina  Hos- 
pital for  Sick  Children,  etc.  Arranged  for  the' press  by  PHILIP  H.  PYE  SMITH, 
M.D.,  Lect.  on  Medicine  in  Guy's  Hospital.  Including  a  section  on  Cutaneous 
Affections,  by  the  Editor;  Chapter  on  Cardiac  Diseases,  by  SAMUEL  WILKES,  M.D., 
F.R.s.,and  Complete  Indexes  by  ROBERT  EDMUND  CARRINGTON.  2  vols.  Royal 
8vo.  Cloth,  $8.00;  Leather,  $ i o.oo  ;  Half  Russia,  $12.00. 

FENWICK'S  Outlines  of  Practice  of  Medicine.  With  Formulas  and  Illustra- 
tions. By  SAMUEL  FENWICK,  M.D.  12010.  Cloth,  $1.25 

FIELD.  Evacuant  Medication — Cathartics  and  Emetics.  By  HENRY  M.  FIELD, 
M.D.,  Professor  of  Therapeutics,  Dartmouth  Medical  College,  Corporate  Mem- 
ber Gynaecological  Society  of  Boston,  etc.  I2mo.  288  pp.  Cloth,  $1.75 

FILLEBROWN.  A  Text-Book  of  Operative  Dentistry.  Written  by  invitation 
of  the  National  Association  of  Dental  Faculties.  By  THOMAS  FILLEBROWN,  M.D., 
D.M.D.,  Professor  of  Operative  Dentistry  in  the  Dental  School  of  Harvard  Uni- 
versity;  Member  of  the  American  Dental  Assoc.,  etc.  Illus.  8vo.  Clo.,  $2.50 

FLAGG.  Plastics  and  Plastic  Fillings,  as  pertaining  to  the  filling  of  all  Cavities 
of  Decay  in  Teeth  below  medium  in  structure,  and  to  difficult  and  inaccessible 
cavities  m  teeth  of  all  grades  of  structure.  By  J.  FOSTER  FLAGG,  D.D.S.,  Professor 
of  Dental  Pathology  in  Philadelphia  Dental  College.  Third  Revised  Edition. 
With  many  Illustrations.  8vo.  Cloth,  $4.00 

FLOWER'S  Diagrams  of  the  Nerves  of  the  Human  Body.  Exhibiting  their 
Origin,  Divisions  and  Connections,  with  their  Distribution  to  the  various  Regions 
of  the  Cutaneous  Surface  and  to  all  the  Muscles.  By  WILLIAM  H.  FLOWER, 
F.R.C.S.,  F.R.S.,  Hunterian  Professor  of  Comparative  Anatomy,  and  Conservator 
of  the  Museum  of  the  Royal  College  of  Surgeons.  Third  Edition,  thoroughly 
revised.  With  six  Large  Folio  Maps  or  Diagrams.  4to.  Cloth,  $3.50 

FLUCKIGER.  The  Cinchona  Barks  Pharmacognostically  Considered.  By 
Professor  FRIEDRICH  FLt)CKiGER,  of  Strasburg.  Translated  by  FREDERICK  B. 
POWER,  PH.D.  With  8  Lithographic  Plates.  Royal  octavo.  Cloth,  $1.50 

FOTHERGILL.  On  the  Heart  and  Its  Diseases.  With  Their  Treatment.  In- 
cluding the  Gouty  Heart.  By  J.  MILNER  FOTHERGILL,  M.D.,  Member  of  the 
Royal  College  of  Physicians  of  London.  2d  Ed.  Rewritten.  8vo.  Cloth,  $3.50 

FOWLER'S  Dictionary  of  Practical  Medicine.  By  Various  Writers.  An  Ency- 
clopedia of  Medicine.  Edited  by  JAMES  KINGSTON  FOWLER,  M.A.,  M.D.,  F.R.C.P., 
Senior  Asst.  Physician  to,  and  Lecturer  on  Pathological  Anatomy  at,  the  Mid- 
dlesex Hospital  and  the  Hospital  for  Consumption  and  Diseases  of  the  Chest, 
Brompton,  London.  8vo.  Just  Ready.  Cloth,  $5.00 ;  Half  Morocco,  $6.00 

FOX.  Water,  Air  and  Food.  Sanitary  Examinations  of  Water,  Air  and  Food. 
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10  P.BLAKISTON,  SON  6-  CO.'S 

FOX   AND   GOULD.     Compend  on  Diseases  of  the  Eye  and  Refraction, 

including  Treatment  and  Surgery.  By  L.WEBSTER  Fox,  M.D.,  Chief  Clinical 
Assistant,  Ophthalmological  Department,  Jefferson  Medical  College  Hospital ; 
Ophthalmic  Surgeon,  Germantown  Hospital,  Philadelphia ;  late  Clinical  Assistant 
at  Moorfields,  London,  England,  etc.,  and  GEO.  M.  GOULD,  M.D.  Second  Edition. 
Enlarged.  71  Illustrations  and  39  Formulas.  Being  No.  8,  ?  Quiz- Compend  ? 
Series.  Cloth,  $1.00.  Interleaved  for  the  addition  of  notes,  $1.25 

FRANKLAND'S  Water  Analysis.  For  Sanitary  Purposes,  with  Hints  for  the  In- 
terpretation of  Results.  By  E.  FRANKLAND,  M.D.,  F.R.S.  Illustrated.  I2mo. 

Cloth,  $1.00 

FULLERTON.  Obstetrical  Nursing.  A  Handbook  for  Nurses,  Students  and 
Mothers.  By  ANNA  M.  FULLERTON,  M.D.,  Demonstrator  of  Obstetrics  in  the 
Woman's  Medical  College ;  Physician  in  charge  of,  and  Obstetrician  and 
Gynaecologist  to,  the  Woman's  Hospital,  Philadelphia,  etc.  34  Illustrations, 
several  of  which  are  original.  I2mo.  212  pages.  Cloth,  $1.25 

GALABIN'S  Midwifery.  A  Manual  for  Students  and  Practitioners.  By  A.  LEWIS 
GALABIN,  M.D.,  F.R.C.P.,  Professor  of  Midwifery  at  and  Obstetric  Physician  to, 
Guy's  Hospital,  London.  227  Illustrations.  Cloth,  $3.00;  Leather,  $3.50 

GARDNER.  The  Brewer,  Distiller  and  Wine  Manufacturer.  A  Handbook  for 
all  Interested  in  the  Manufacture  and  Trade  of  Alcohol  and  Its  Compounds. 
Edited  by  JOHN  GARDNER,  F.C.S.  Illustrated.  Cloth,  $1.75 

Bleaching,  Dyeing,  and  Calico  Printing.  With  Formulae.    Illustrated.     $1.75 
Acetic  Acid,  Vinegar,  Ammonia  and  Alum.     Illustrated.  Cloth,  $1.75 

GARROD.  On  Rheumatism.  A  Treatise  on  Rheumatism  and  Rheumatic  Arthritis. 
BY  ARCHIBALD  EDWARD  GARROD,  M.A.  Oxon.,  M.D.,  M.R.C.S.  Eng.,  Asst.  Phy- 
sician, West  London  Hospital.  Illustrated.  Octavo.  Cloth,  $6  oo 

GIBBES'S  Practical  Histology  and  Pathology.  By  HENEAGE  GIBBES,  M.B.  i2mo. 
Third  Edition.  Cloth,  $1.75 

GILLIAM'S  Pathology.  The  Essentials  of  Pathology ;  a  Handbook  for  Students. 
By  D.  TOD  GILLIAM,  M.D.,  Professor  of  Physiology,  Starling  Medical  College, 
Columbus,  O.  With  47  Illustrations.  I2mo.  Cloth,  $2.00 

GLISAN'S  Modern  Midwifery.  A  Text-book.  By  RODNEY  GLISAN,  M.D.,  Emeritus 
Professor  of  Midwifery  and  Diseases  of  Women  and  Children  in  Willamette 
Univ.,  Portland,  Oregon.  129  Illus.  8vo.  2d  Edition.  Cloth,  $3.00 

GOODHART  and  STARR'S  Diseases  of  Children.  The  Student's  Guide  to  the 
Diseases  of  Children.  By  J.  F.  GOODHART,  M.D.,  F.R.C.P.,  Physician  to  Evelina 
Hospital  for  Children;  Demonstrator  of  Morbid  Anatomy  at  Guy's  Hospital. 
Second  American  from  the  Third  English  Edition.  Rearranged  and 
Edited,  with  notes  and  additions,  by  Louis  STARR,  M.D.,  Clinical  Professor  of  Dis- 
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Hospital.  With  many  ne'w  prescriptions.  Cloth,  $3.00;  Leather,  $3.50 

GORGAS'S  Dental  Medicine.  A  Manual  of  Materia  Medica  and  Therapeutics. 
By  FERDINAND  J.  S.  GORGAS,  M.D.,  D.D.S.,  Professor  of  the  Principles  of  Dental 
Science,  Dental  Surgery  and  Dental  Mechanism  in  the  Dental  Department  of 
the  University  of  Maryland.  Thiid  Edition.  Enlarged.  8vo.  Cloth,  $3.50 

GOULD'S  New  Medical  Dictionary.  Including  all  the  Words  and  Phrases  used 
in  Medicine,  with  their  proper  Pronunciation  and  Definitions,  based  on  Recent 
Medical  Literature.  By  GEORGE  M.  GOULD,  B.A.,  M.D.,  Ophthalmic  Surgeon  to 
the  Philadelphia  Hospital,  etc.,  With  Tables  of  the  Bacilli,  Micrococci,  Leuco- 
maines,  Ptomaines,  etc.,  of  the  Arteries,  Muscles,  Nerves,  Ganglia  and  Plexuses; 
Mineral  Springs  of  U.  S.,  Vital  Statistics,  etc.  Small  octavo,  520  pages. 

Half  Dark  Leather,  $3.25;  Half  Morocco,  Thumb  Index,  $4.25 


MEDICAL  AND  SCIENTIFIC  PUBLICA  TIONS.  11 

GOWERS,  Manual  of  Diseases  of  the  Nervous  System.  A  Complete  Text-book, 
By  WILLIAM  R.  GOWERS,  M.D.,  Prof.  Clinical  Medicine,  University  College, 
London.  Physician  to  National  Hospital  for  the  Paralyzed  and  Epileptic.  341 
Illustrations  and  1360  pages.  Octavo.  New  Edition  Preparing. 

Diagnosis  of  Diseases  of  the  Brain.    8vo.    Second  Ed.    Illus.    Cloth,  $2.00 
Diagnosis  of  Diseases  of  the  Spinal  Cord.    4th  Edition.  Preparing. 

Medical  Ophthalmoscopy.  A  Manual  and  Atlas,  with  Colored  Autotype  and 
Lithographic  Plates  and  Wood-cuts,  comprising  Original  Illustrations  of  the 
changes  of  the  Eye  in  Diseases  of  the  Brain,  Kidney,  etc.  Third  Edition. 
Revised,  with  the  assistance  of  R.  MARCUS  GUNN,  F.R.C.S.,  Surgeon,  Royal 
London  Ophthalmic  Hospital,  Moorfields.  Octavo.  Cloth,  $5.50 

Syphilis  and  the  Nervous  System.  Being  the  Lettsomian  Lectures  for  1 889. 
8vo.  In  Press. 

GROSS'S  Biography  of  John  Hunter.  John  Hunter  and  His  Pupils.  By  Profes- 
sor S.  D.  GROSS,  M.D.  With  a  Portrait.  8vo.  Paper,  .75;  Cloth,  $1.25 

GREENHOW.  Chronic  Bronchitis,  especially  as  connected  with  Gout,  Emphysema, 
aud  Diseases  of  the  Heart.  By  E.  HEADLAM  GREENHOW,  M.D.  i2mo. 

Paper,  .75;  Cloth,  $1.25 

GRIFFITH'S  Graphic  Clinical  Chart.  Designed  by  J.  P.  CROZER  GRIFFITH, 
M.D.,  Instructor  in  Clinical  Medicine  in  the  University  of  Pennsylvania.  Printed 
in  three  colors.  Sample  copies  free.  Put  up  in  loose  packages  of  50,  .50 

Price  to  Hospitals,  500  copies,  $4.00;  1000  copies,  $7.50.  With  name  of  Hos- 
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GROVES  AND  THORP.  Chemical  Technology.  A  new  and  Complete  Work. 
The  Application  of  Chemistry  to  the  Arts  and  Manufactures.  Edited  by 
CHARLES  E.  GROVES,  F.R.S.,  and  WM.  THORP,  B.SC.,  F.I.C.  In  about  eight  vol- 
umes, with  numerous  illustrations.  Each  volume  sold  separately, 

Vol.  I.  FUEL.  By  Dr.  E.  J.  MILLS,  F.R.S.,  Professor  of  Chemistry,  Anderson 
College,  Glasgow;  and  Mr.  F.  J.  ROWAN,  assisted  by  an  American  expert.  607 
Illustrations  and  4  plates.  Octavo.  Cloth,  7.50;  Half  Morocco,  $9.00 

HABERSHON.  On  Some  Diseases  of  the  Liver.  By  S.  O.  HABERSHON,  M.D., 
F.R.C.P.,  late  Senior  Physician  to  Guy's  Hospital.  A  New  Edition.  Cloth,  #1.50 

HADDON'S  Embryology.  An  Introduction  to  the  Study  of  Embryology.  For 
the  Use  of  Students.  By  A.  C.  HADDON,  M.A.,  Prof,  of  Zoology,  Royal  College 
of  Science,  Dublin.  190  Illustrations.  Cloth,  $6.00 

HALE.  On  the  Management  of  Children  in  Health  and  Disease.  A  Book  for 
Mothers.  By  AMIE  M.  HALE,  M.D.  New  Enlarged  Edition.  I2mo.  Cloth,  .75 

HARE.  Mediastinal  Disease.  The  Pathology,  Clinical  History  and  Diagnosis  of 
Affections  of  the  Mediastinum  other  than  those  of  the  Heart  and  Aorta,  with 
tables  giving  the  Clinical  History  of  520  cases.  The  essay  to  which  was  awarded 
the  Fothergillian  Medal  of  the  Medical  Society  of  London,  1888.  By  H.  A. 
HARE,  M.D.  (Univ.  of  Pa.),  Demonstrator  of  Therapeutics  and  Instructor  in  Phy- 
sical Diagnosis  in  the  Medical  Department,  and  Instructor  in  Physiology  in  the 
Biological  Department,  Univ  of  Pa.  8vo.  Illustrated  by  Six  Plates.  Cloth,  $2.00 

HARLAN.  Eyesight,  and  How  to  Care  for  It.  By  GEORGE  C.  HARLAN,  M.D., 
Prof,  of  Diseases  of  the  Eye,  Philadelphia  Polyclinic.  Illustrated.  Cloth,  .50 

HARLEY.  Diseases  of  the  Liver,  With  or  Without  Jaundice.*  Diagnosis  and 
Treatment.  By  GEORGE  HARLEY,  M.D.  With  Colored  Plates  and  Numerous 
Illustrations.  8vo.  Price  reduced.  Cloth,  $3.00  ;  Leather,  $4.00 

HARRIS.  On  the  Chest.  Including  the  Principal  Affections  of  the  Pleurae,  Lungs, 
Pericardium,  Heart  and  Aorta.  By  VINCENT  D.  HARRIS,  F.R.C.P.,  Physician  to 
the  Victoria  Park  Hospital  for  Diseases  of  the  Chest,  London.  With  55  Illus- 
trations. Cloth,  $2.50 


12  P.  BLAKISTON,  SON  <S-  CO.'S 

HARRIS'S  Principles  and  Practice  of  Dentistry.  Including  Anatomy,  Physi- 
ology, Pathology,  Therapeutics,  Dental  Surgery  and  Mechanism.  By  CHAPIN  A. 
HARRIS,  M.D.,  D.D.S.,  late  President  of  the  Baltimore  Dental  College,  author  of 
"Dictionary  of  Medical  Terminology  and  Dental  Surgery."  Twelfth  Edition. 
Revised  and  Edited  by  FERDINAND  J.  S.  GORGAS,  A.M.,  M.D.,  D.D.S.,  author  ot 
"  Dental  Medicine ;"  Professor  of  the  Principles  of  Dental  Science,  Dental 
Surgery  and  Dental  Mechanism  in  the  University  of  Maryland.  Two  Full-page 
Plates  and  1086  Illustrations.  1225  pages.  8vo.  Cloth,  $7.00;  Leather,  $8.00 

Medical  and  Dental  Dictionary.  A  Dictionary  of  Medical  Terminology, 
Dental  Surgery,  and  the  Collateral  Sciences.  Fourth  Edition,  carefully 
Revised  and  Enlarged.  By  FERDINAND  J.  S.  GORGAS,  M.D.,  D.D.S.,  Prof,  of 
Dental  Surgery  in  the  Baltimore  College.  8vo.  Cloth,  $6.50  ;  Leather,  $7  50 

HARTRIDGE.  Refraction.  The  Refraction  of  the  Eye.  A  Manual  for  Students. 
By  GUSTAVUS  HAKTRIDGE,  F.R.C.S.;  Consulting  Ophthalmic  Surgeon  to  St.  Bar- 
tholomew's Hospital ;  Ass't  Surgeon  to  the  Royal  Westminster  Ophthalmic  Hos- 
pital, etc.  96  Illustrations  and  Test  Types.  Fourth  Edition.  Cloth,  $2.00 

HARTSHORNE.  Our  Homes.  Their  Situation,  Construction,  Drainage,  etc.  By 
HENRY  HARTSHORNE,  M.D.  Illustrated.  Cloth,  .50 

HATFIELD.  Diseases  of  Children.  By  MARCUS  P.  HATFIELD,  Professor  of 
Diseases  of  Children,  Chicago  Medical  College.  With  a  Colored  Plate.  Being 
NO.IJ.,?  Quiz- Compend?  Series.  I2mo.  Cloth,  $1.00 

Interleaved  for  the  addition  of  notes,  $1.25 

HEADLAND'S  Action  of  Medicines.  On  the  Action  of  Medicines  in  the  System. 
By  F.  W.  HEADLAND,  M.D.  Ninth  American  Edition.  8vo.  Cloth,  $3.00 

HEATH'S  Operative  Surgery.  A  Course  of  Operative  Surgery,  consisting  of  a 
Series  of  Plates,  Drawn  from  Nature  by  M.  Leveille,  of  Paris.  With  Descriptive 
Text  of  Each  Operation.  By  CHRISTOPHER  HEATH,  F.R.C.S.,  Holme  Professor 
of  Clinical  Surgery  in  University  College,  London.  Quarto.  Second  Edition. 
Revised.  Sold  by  Subscription.  Cloth,  $12.00 

Minor  Surgery  and  Bandaging.  Ninth  Edition.  Revised  and  Enlarged. 
With  142  Illustrations.  I2mo.  Cloth,  $2.00 

Practical  Anatomy.  A  Manual  of  Dissections.  Seventh  London  Edition. 
24  Colored  Plates,  and  nearly  300  other  Illustrations.  Cloth,  $5.00 

Injuries  and  Diseases  of  the  Jaws.  Third  Edition.  Revised,  with  over 
150  Illustrations.  8vo.  Cloth,  $4.50 

Lectures  on  Certain  Diseases  of  the  Jaws,  delivered  at  the  Royal  College  of 
Surgeons  of  England,  1887.  64  Illustrations.  8vo.  Boards,  #1.00 

HENRY.  Anaemia.  •'  A  Practical  Treatise.  By  FRED'K  P.  HENRY,  M.D.,  Prof. 
Clinical  Med.  Phila.  Polyclinic,  Physician  to  Episcopal  and  Phila.  Hospitals,  to 
Home  for  Consumptives,  etc.  I2mo.  Half  Cloth,  .75 

HIGGENS'  Ophthalmic  Practice.     A  Manual  for  Students  and  Practitioners.     By 

CHARLES  HIGGENS,  F.R.C.S.    Ophthalmic  Surgeon  at  Guy's  Hospital.     Practical 

Series.     See  Page  19.  Cloth,  $1.75 

Ophthalmic  Practice.    A  Handbook.    Second  Edition.    32mo.      Cloth,  .50 

HILL  AND  COOPER.  Venereal  Diseases.  The  Student's  Manual  of  Venereal 
Diseases,  being  a  concise  description  of  those  Affections  and  their  Treatment. 
By  BERKELEY  HILL,  M.D.,  Professor  of  Clinical  Surgery,  University  College,  and 
ARTHUR  COOPER,  M.D.,  Late  House  Surgeon  to  the  Lock  Hospital,  London. 
4th  Edition.  i2mo.  Cloth,  #1.00 


MEDICAL  AND  SCIENTIFIC  PUBLICATIONS.  13 

HOLDEN'S  Anatomy.  A  Manual  of  the  Dissections  of  the  Human  Body.  By 
LUTHER  HOLDEN,  F.R.C.S.  Fifth  Edition.  Carefully  Revised  and  Enlarged. 
Specially  concerning  the  Anatomy  of  the  Nervous  System,  Organs  of  Special 
Sense,  etc.  By  JOHN  LANGTON,  F.R.C.S.,  Surgeon  to,  and  Lecturer  on  Anatomy 
at,  St.  Bartholomew's  Hospital.  208  Illustrations.  8vo. 

Oilcloth  Covers,  for  the  Dissecting  Room,  $4.50;  Cloth,  $5.00;  Leather,  $6.00 

Human  Osteology.  Comprising  a  Description  of  the  Bones,  with  Colored 
Delineations  of  the  Attachments  of  the  Muscles.  The  General  and  Micro- 
scopical Structure  of  Bone  and  its  Development.  Carefully  Revised.  By 
the  Author  and  Prof.  STEWART,  of  the  Royal  College  of  Surgeons'  Museum. 
With  Lithographic  Plates  and  Numerous  Illustrations,  yth  Ed.  Cloth,  $6.00 

Landmarks.     Medical  and  Surgical.     4th  Edition.     8vo.  Cloth,  $1.25 

HOLLAND.  The  Urine,  the  Common  Poisons  and  the  Milk.  Memoranda,  Chem- 
ical and  Microscopical,  for  Laboratory  Use.  By  J.  W.  HOLLAND,  M.D.,  Professor 
of  Medical  Chemistry  and  Toxicology  in  Jefferson  Medical  College,  of  Philadel- 
phia. Third  Edition.  Revised  and  Enlarged.  Illustrated  and  Interleaved. 
I2mo.  Cloth,  $1.00 

HORWITZ'S  Compend  of  Surgery,  including  Minor  Surgery,  Amputations,  Frac- 
tures, Dislocations,  Surgical  Diseases,  and  the  Latest  Antiseptic  Rules,  etc.,  with 
Differential  Diagnosis  and  Treatment.  By  ORVILLE  HORWITZ,  B.S.,  M.D.,  Dem- 
onstrator of  Anatomy,  Jefferson  Medical  College ;  Chief,  Out- Patient  Surgical 
Department,  Jefferson  Medical  College  Hospital.  Third  Edition.  Very  much 
Enlarged  and  Rearranged.  91  Illustrations  and  77  Formulae.  I2mo.  No.qfQuiz- 
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HUFELAND.  Long  Life.  Art  of  Prolonging  Life.  By  C.  W.  HUFELAND. 
Edited  by  ERASMUS  WILSON,  M.D.  i2mo.  Cloth,  $1.00 

HUGHES.  Compend  of  the  Practice  of  Medicine.  Fourth  Edition.  Revised  and 
Enlarged.  By  DANIEL  E.  HUGHES,  M.D.,  Demonstrator  of  Clinical  Medicine  a 
Jefferson  Medical  College,  Philadelphia.  In  two  parts.  Being  Nos.  2  and  j» 
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PART  I. — Continued,  Eruptive  and  Periodical  Fevers,  Diseases  of  the  Stomach. 
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vous System  ;  Diseases  of  the  Blood,  etc. 

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Physicians'  Edition. — In  one  volume,  including  the  above  two  parts,  a  sec- 
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462  pages.  Full  Morocco,  Gilt  Edge,  $2.50 

HUMPHREY.  A  Manual  for  Nurses.  Including  general  Anatomy  and  Physiology, 
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bridge, England.  I2mo.  Illustrated.  242  pages.  Cloth,  $1.25 

JACOBSON.  Operations  of  Surgery.  By  W.  H.  A.  JACOBSON,  B.A.  OXON., 
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JAMES  on  Sore  Throat.  Its  Nature,  Varieties  and  Treatment,  including  its  Con- 
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vised and  Enlarged.  Colored  Plates  and  Wood-cuts.  Paper  .75  ;  Cloth,  $1.25 

JONES'  Aural  Surgery.  A  Practical  Handbook  on  Aural  Surgery.  By  H. 
MACNAUGHTON  JONES,  M.D.,  Surgeon  to  the  Cork  Ophthalmic  and  Aural  Hospital. 
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14  P.  BLAKISTON,  SON  <S-  CO.'S 

KEATING.  How  to  Examine  for  Life  Insurance.  A  Practical  Handbook.  Bv 
JOHN  M.  KEATING,  President  of  the  Association  of  Life-Insurance  Medical  Direc- 
tors. With  3  Full-page  Plates  and  other  Illustrations.  8vo.  Cloth,  net,  $2.00. 

KIRKES'  Physiology.  (Authorized  Edition.}  A  Handbook  of  Physiology. 
Twelfth  London  Edition,  Revised  and  Enlarged.  By  W.  MORRANT  BAKER, 
M.D.  460  Illustrations.  I2mo.  880  Pages.  Cloth,  $4.00;  Leather,  #5  oo 

LANDIS'  Compend  of  Obstetrics  ;  especially  adapted  to  the  Use  of  Students  an'1 
Physicians.  By  HENRY  G.  LANDIS,  M.D.,  Professor  of  Obstetrics  and  Diseases 
of  Women,  in  Starling  Medical  College,  Columbus,  Ohio.  Fourth  Edition. 
Enlarged.  With  Many  Illustrations.  No.  5  f  Quiz-  Compend ?  Series. 

Cloth,  $1.00;  interleaved  for  the  addition  of  Notes,  $1.25 

LANDOIS.  A  Text-Book  of  Human  Physiology  ;  including  Histology  and  Micro- 
scopical Anatomy,  with  special  reference  to  the  requirements  of  Practical  Medi- 
cine. By  DR.  L.  LANDOIS,  Professor  of  Physiology  and  Director  of  the  Physio- 
logical Institute  in  the  University  of  Greifswald.  Third  American,  translated 
from  the  Sixth  German  Edition,  with  additions,  by  WM.  STIRLING,  M.D.,  D.SC., 
Brackenbury  Professor  of  Physiology  and  Histology  in  Owen's  College,  Man- 
chester ;  Examiner  in  Physiology  in  University  of  Oxford,  England.  With  692 
Illustrations.  8vo.  Cloth,  $6.50;  Leather,  $7.50 

LEBER  AND  ROTTENSTEIN.  Dental  Caries  and  Its  Causes.,  An  Investigation 
into  the  Influence  of  Fungi  in  the  Destruction  of  the  Teeth.  By  Drs.  LEBER 
and  ROTTENSTEIN.  Illustrated.  Paper,  .75  ;  Cloth,  $1.25 

LEE.  The  Microtomist's  Vade  Mecum.  Second  Edition.  A  Handbook  of 
Methods  of  Microscopical  Anatomy.  By  ARTHUR  BOLLES  LEE,  Asst.  in  the  Rus- 
sian Laboratory  of  Zoology,  at  Villefranche-sur-Mer  (Nice).  660  Formulae,  etc. 
Enlarged  and  Revised.  Cloth,  $4.00 

LEFFM ANN'S  Compend  of  Chemistry,  Inorganic  and  Organic.  Including  Urine 
Analysis.  By  HENRY  LEFFMANN,  M.D.,  Prof,  of  Chemistry  and  Metallurgy  in 
the  Penna.  College  of  Dental  Surgery,  and  in  the  Wagner  Free  Institute  of 
Science,  Philadelphia.  No.  10  ? Quiz- Compend ?  Seties.  Third  Edition.  Re- 
written and  Adapted  for  Students  of  Medicine  and  Dentistry.  I2mo. 

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Penna.  College  of  Dental  Surgery.  Hygienist  and  Food  Inspector  Penna.  State 
Board  of  Agriculture,  etc.;  and  WILLIAM  BEAM,  A.M.,  formerly  Chief  Chemist 
B.  &  O.  R.  R.  Second  Edition.  Enlarged.  Illustrated.  I2mo.  Cloth,  $1.25 
Progressive  Exercises  in  Practical  Chemistry.  A  Laboratory  Handbook. 
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Illustrated.  I2mo.  Cloth,  .75 

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MEDICAL  AND  SCIENTIFIC  PUBL1CA  TIONS.  15 

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16  P.  BLAKISTON,  SON  <S-  CO.'S 

MARSHALL  &  SMITH.  On  the  Urine.  The  Chemical  Analysis  of  the  Urine. 
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MEDICAL  Directory  of  Philadelphia  and  Camden,  1889.  Containing  lists  of 
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MEYER.  Ophthalmology.  A  Manual  of  Diseases  of  the  Eye.  By  DR.  EDOUARD 
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MEDICAL  AND  SCIENTIFIC  PUBLICA  TIONS.  17 

MORTON  on  Refraction  of  the  Eye.  Its  Diagnosis  and  the  Correction  of  its  Errors. 
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OSTROM.  Massage  and  the  Original  Swedish  Movements.  Their  Application 
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18  P.  BLAKISTON,  SON  <S-  CO.'S  PUBLICATIONS. 

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THE  PRACTICAL  SERIES. 


THREE  NEW  VOLUMES. 


PARKES.  Hygiene  and  Public  Health.  A  Practical  Manual.  By  Louis  C. 
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sician to  Out-patients,  Queen  Charlotte's  Lying-in  Hospital ;  Examiner  in  Mid- 
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146  Engravings.  Second  Edition,  Revised.  Cloth,  $2.50 

BTTXTOII.  On  Anaesthetics.  A  Manual  of  their  Uses  and  Administration.  By 
DUDLEY  WILMOT  BUXTON,  M.D.,  B.S.,  Ass't  to  Prof,  of  Med.,  and  Administrator 
of  Anaesthetics,  University  College  Hospital,  London.  Illustrated. 

Second  Edition  in  Press. 


MONEY.  On  Children.  Treatment  of 
Disease  in  Children,  including  the  Out- 
lines of  Diagnosis  and  the  Chief 
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M.D.,  M.R.C.P.,  Ass't  Physician  to  the 
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Chest  Hospital,  London.  I2mo.  560 
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PRITCHARD.  On  the  Ear.  Handbook 
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of  Aural  Surgery,  King's  College, 
London,  Aural  Surgeon  to  King's 
College  Hospital,  Senior  Surgeon  to 
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BARRETT.  Dental  Surgery  for  Gen- 
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COLLIE  On  Fevers.  A  Practical  Treat- 
ise on  Fevers,  Their  History,  Etiology. 
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RALFE.    Diseases  of  the  Kidney  and 

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REEVES.  Bodily  Deformities  and 
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20  P.  BLAKISTON,  SON  S-  CO.'S 

POTTER.  Compend  of  Anatomy,  including  Visceral  Anatomy.  Formerly  pub- 
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Aural  Surgeon  to  King's  College  Hospital,  Senior  Surgeon  to  the  Royal  Ear 
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RALEE.     Diseases  of  the  Kidney  and  Urinary  Derangements.     By  C.  H.  RALFE. 

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REEVES.     Bodily  Deformities  and  their  Treatment.     A  Handbook  of  Practical 

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RICHARDSON.  Long  Life,  and  How  to  Reach  It.  By  J.  G.  RICHARDSON,  Prof, 
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With  569  Illustrations.  8vo.  Cloth,  $4.50;  Leather,  $5.50 

RIGBY'S  Obstetric  Memoranda.    4th  Ed.    By  MEADOWS.    321110.         Cloth,  .50 

RICHTER'S  Inorganic  Chemistry.    A  Text-book  for  Students.    By  Prof.  VICTOR 

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Edition.     Authorized  Translation   by  EDGAR  F..  SMITH,  M.A.,  PH.D.,  Prof,  of 

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ROBERTS.  Bow-Legs.  Clinical  Lectures  on  Orthopaedic  Surgery.  By  A.  SYDNEY 
ROBERTS,  M.D.,  Instructor  in  Orthopaedic  Surg.  in  the  Univ.  of  Penn'a,  Surg.  to 
the  Univ.  Hospital.  Illustrated.  I2mo  Cloth,  .50;  Boards,  .50 

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Materia  Medica  and  Pharmacy.    A  Compend  for  Students.       Cloth,  $2.00 

ROBINSON.  Latin  Grammar  of  Pharmacy  and  Medicine.  By  D.  H.  ROBINSON, 
PH.D.,  Professor  of  Latin  Language  and  Literature,  University  of  Kansas,  Law- 
rence. With  an  Introduction  by  L.  E.  SAYRE,  PH.G.,  Professor  of  Pharmacy  in, 
and  Dean  of  the  Dept.  of  Pharmacy,  University  of  Kansas.  I2mo.  Cloth,  $2.00 

SANDERSON'S  Physiological  Laboratory.  A  Handbook  of  the  Physiological 
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SCANZONI.  Sexual  Organs  of  Women.  A  Practical  Treatise  on  the  Diseases 
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and  Diseases  of  Females,  University  of  Wiirzburg,  etc.  Edited  by  A.  K.  GARD- 
NER, A.M.,  M.D.  60  Illustrations.  Fourth  Edition.  Octavo.  Cloth,  $4.00 

SCHNEE.  Diabetes,  its  Cause  and  Permanent  Cure.  From  the  standpoint  of  ex- 
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at  Carlsbad.  Translated  from  the  German  by  R.  L.  TAFEL,  A.M.,  PH.D.  Re- 
vised and  Enlarged  by  the  author.  Octavo.  Cloth,  $2.00 

SEWELL.  Dental  Surgery,  including  Special  Anatomy  and  Surgery.  By  HENRY 
SEWELL,  M.R.C.S.,  L.D.S.,  President  Odontological  Society  of  Great  Britain.  3d 
Edition,  greatly  enlarged,  with  about  200  Illustrations.  Cloth,  $3.00 

SMITH'S  Wasting  Diseases  of  Infants  and  Children.  By  EUSTACE  SMITH,  M.D., 
F.R.C.P.,  Physician  to  the  East  London  Children's  Hospital.  Fifth  London 
Edition,  Enlarged.  8vo.  Cloth,  $3.00 

Clinical  Studies  of  Diseases  in  Children.    Second  Edition.       Cloth,  $2.50 

SMITH.  Abdominal  Surgery.  Being  a  Systematic  Description  of  all  the  Princi- 
pal Operations.  By  J.  GREIG  SMITH,  M.A.,  F.R.S.E.,  Surg.  to  British  Royal  In- 
firmary. Illustrated.  Third  Edition.  Cloth,  $7.00 

SMITH.  Electro-Chemical  Analysis.  By  EDGAR  F.  SMITH,  Prof,  of  Analytical 
Chemistry,  University  of  Penna.  26  Illustrations.  I2mo.  Cloth,  $1.00 

SMITH  (TYLER).  Lectures  on  Obstetrics.  Delivered  at  St.  Mary's  Hospital. 
With  an  Introductory  Lecture  on  the  History  and  Art  of  Midwifery,  and  Copious 
Annotations.  By  A.  K.  GARDNER,  A.M.,  M.D.  233  lllus.  3d  Ed.  8vo.  Cloth,  #4.00 

STAMMER.  Chemical  Problems,  with  Explanations  and  Answers.  By  KARL 
STAMMER.  Translated  from  the  2d  German  Edition,  by  Prof.  W.  S.  HOSKINSON, 
A.M.,  Wittenberg  College,  Springfield,  Ohio.  I2mo.  Cloth.  .75 

STARR  and  WALKER.  Physiological  Action  of  Medicines.  Prepared  for  the 
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Enlarged.  321110.  Cloth,  .75 

STARR.  The  Digestive  Organs  in  Childhood.  Second  Edition.  The  Diseases 
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M.D..  late  Clinical  Prof,  of  Diseases  of  Children  in  the  Hospital  of  the  University 
of  Penn'a;  Physician  to  the  Children's  Hospital,  Phila.  Second  Edition. 
Revised  and  Enlarged.  Illustrated  by  two  Colored  Lithograph  Plates  and 
numerous  wood-engravings.  Crown  Octavo.  Cloth,  $2.25 

The  Hygiene  of  the  Nursery,  including  the  General  Regimen  and  Feed. 
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Emergencies  of  Early  Life.  Second  Edition.  Enlarged.  24  Illustrations. 
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cal Pharmacy,  Phila.  College  of  Pharmacy  ;  Demonstrator  and  Lect.  in  Pharma- 
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22  P.  BLAKISTON,  SON  &*  CO.'S 

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mental Physiology,  with  Special  Reference  to  Practical  Medicine.  By  W.  STIR- 
LING, M.D.,  SC.D.,  Prof,  of  Phys.,  Owens  College,  Victoria  University,  Manchester. 
Examiner  in  Honors  School  of  Science,  Oxford,  England.  142  Illustrations. 
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Outlines  of  Practical  Histology.  A  Manual  for  Students.  With  344  Illus- 
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STOCKEN'S  Dental  Materia  Medica.  Dental  Materia  Medica  and  Therapeutics, 
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STRAHAN.  Extra-Uterine  Pregnancy.  The  Diagnosis  and  Treatment  of  Extra- 
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of  Philadelphia.  By  JOHN  STRAHAN,  M.D.  (Univ.  of  Ireland),  late  Res.  Surgeon 
Belfast  Union  Infirmary  and  Fever  Hospital.  Octavo.  '  Cloth,  $1.50 

BUTTON'S  Volumetric  Analysis.  A  Systematic  Handbook  for  the  Quantitative 
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SUTTON.  Ligaments.  Their  Nature  and  Morphology.  By  JOHN  BLAND  SUTTON, 
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Dem.  of  Anatomy,  Middlesex  Hospital,  London.  Illustrated.  I2mo.  Cloth,  $1.25 

SWAIN.  Surgical  Emergencies,  together  with  the  Emergencies  Attendant  on 
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SWANZY.  Diseases  of  the  Eye  and  their  Treatment.  A  Handbook  for  Physi- 
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the  National  Eye  and  Ear  Infirmary  ;  Ophthalmic  Surgeon  to  the  Adelaide  Hos- 
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S WAYNE'S  Obstetric  Aphorisms,  for  the  Use  of  Students  commencing  Midwifeiy 
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SYMONDS.  Manual  of  Chemistry,  for  the  special  use  of  Medical  Students.  By 
BRANDRETH  SYMONDS,  A.M.,  M.D.,  Asst.  Physician  Roosevelt  Hospital,  Out- 
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lustrations. 8vo.  Cloth,  $4.25  ;  Leather,  $5.00 
Index  of  Dental  Periodical  Literature  8vo.  Cloth,  $2.00 

TALBOT.  Irregularities  of  the  Teeth,  and  Their  Treatment.  By  EUGENE  S. 
TALBOT,  M.D.,  Professor  of  Dental  Surgery  Woman's  Medical  College,  and 
Lecturer  on  Dental  Pathology  in  Rush  Medical  College,  Chicago.  Second  Edi- 
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(169  of  which  are  original).  261  pages.  Cloth,  $3.00 

TANNER'S  Index  of  Diseases  and  their  Treatment.  By  THOS.  HAWKES  TANNER, 
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TILT'S  Change  of  Life  in  Women,  in  Health  and  Disease.  A  Practical  Treatise 
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TILT,  M.D.  Fourth  London  Edition.  8vo.  Paper  cover,  .75  ;  Cloth,  $1.25 

TOMES'  Dental  Anatomy.  A  Manual  of  Dental  Anatomy,  Human  and  Compara- 
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Dental  Surgery.  A  System  of  Dental  Surgery.  By  JOHN  TOMES,  F.R.S. 
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TRIMBLE.  Practical  and  Analytical  Chemistry.  Being  a  complete  course  in 
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TURNBULL'S  Artificial  Anaesthesia.  The  Advantages  and  Accidents  of  Artifi- 
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TUSON.  Veterinary  Pharmacopoeia.  Including  the  Outlines  of  Materia  Medica 
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24  P.  BLAKISTON,  SON  &>  CO.'S 

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Anatomy  in  the  University  of  Pennsylvania.  Including  a  Section  on  Retinitis  in 
Bright's  Disease.  By  WM.  F.  NORRIS,  M.D.,  Clin.  Prof,  of  Ophthalmology,  in  Univ. 
of  Penna.  With  Colored  Plates  and  many  Wood  Engravings.  8vo.  Cloth,  $3.50 

Guide  to  the  Examination  of  Urine.    Seventh  Edition.    For  the  Use  of 

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Cell  Doctrine.  Its  History  and  Present  State.  With  a  Copious  Bibliography 
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VAN  HAELIN6EN  on  Skin  Diseases.  A  Practical  Manual  of  Diagnosis  and 
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VAN  NUYS  on  The  Urine.  Chemical  Analysis  of  Healthy  and  Diseased  Urine, 
Qualitative  and  Quantitative.  By  T.  C.  VAN  NUYS,  Professor  of  Chemistry 
Indiana  University.  39  Illustrations.  Octavo.  Cloth,  $2.00 

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Cellular  Pathology,  as  based  upon  Physiological  and  Pathological  Histology. 
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WALSH  AM.  Manual  of  Practical  Surgery.  For  Students  and  Physicians.  By 
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WARREN,  D.D.S.,  Clinical  Chief,  Penn'a  College  of  Dental  Surgery,  Phila.  Illus. 
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By  C.  J.  B.  WILLIAMS,  M.D.  Second  Edition.  Enlarged  and  Rewritten.  By  C. 
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eases of  the  Bladder  and  Urethra.  By  Dr.  F.  WINCKEL,  Professor  of 
Gynaecology,  and  Director  of  the  Royal  University  Clinic  for  Women,  in  Munich. 
Translated  by  special  authority  of  Author  and  Publisher,  under  the  supervision 
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WOLFF.  Manual  of  Applied  Medical  Chemistry  for  Students  and  Practitioners  of 
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WOODY.  Essentials  of  Chemistry  and  Urinalysis.  By  SAM  E.  WOODY,  A.M., 
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WYNTER  and  WETHERED.  Clinical  and  Practical  Pathology.  A  Manual 
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istrar and  late  Dem.  of  Anat.  and  Chem.  at  the  Middlesex  Hospital,  and 
FRANK  J.  WETHERED,  M.D.,  Asst.  Phys.  to  the  City  of  London  Hospital  for  Dis. 
of  the  Chest.  4  Colored  Plates  and  67  other  Illustrations.  8vo.  Cloth,  $4.00 
WYTHE  on  the  Microscope.  A  Manual  of  Microscopy  and  Compendium  of  the 
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YEO'S  Manual  of  Physiology.  Fourth  Edition.  A  Text-book  for  Students  of 
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price  at  which  they  have  been  published  is  an  additional  point  in  their  favor.  Full  circular,  descriptive  of 
the  Series,  will  be  sent  upon  application. 

WALSHAM'S  PRACTICAL  SURGERY.  A  Manual  for  Students  and  Physicians.  By  WM.  J. 
WALSHAM,  M.D.,  Asst.  Surgeon  to,  and  Demonstrator  of  Surgery  in,  St.  Bartholomew's  Hospital;  Sur- 
geon to  Metropolitan  Free  Hospital,  London,  etc.  236  Illust.  656  pp.  t 

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From  the  Polyclinic. 

"  While  evidently  intended  to  be  a  text-book  for  students,  and  therefore  small  in  size  and  compactly  written,  is  neverthe- 
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involved  in  the  treatment  of  the  ordinary  run  of  surgical  cases.  The  author  seems  to-be  a  conservative  and  judicious  surgeon 

PARVIN'S-WINCKEL'S  DISEASES  OF  WOMEH.  Second  Edition.  A  Treatise  on  the  Dis- 
eases of  Women.  Including  the  Diseases  of  the  Bladder  and  Urethra.  By  DR.  F.  WINCKEL,  Professor 
of  Gynaecology  and  Director  of  the  Royal  University  Clinic  for  Women,  in  Munich.  Revised  and  Edited 
by  THEOPHILUS  PARVIN,  M.D.,  Professor  of  Obstetrics  and  Diseases  of  Women  and  Children  in  Jeffer- 
son Medical  College.  Illustrated  by  150  fine  Engravings  on  Wood,  most  of  which  are  new.  760  pp. 

Cloth,  $300;  Leather,  $3.50 

GALABIN'S  MIDWIFERY.  A  Manual  of  Widwifery.  By  AIFRED  LEWIS  GALABIN,  M.A.,  M.D., 
Obstetric  Physician  and  Lecturer  on  Midwifery  and  the  Diseases  of  Women  at  Guy's  Hospital,  London; 
Examiner  in  Midwifery  to  the  Conjoint  Examining  Board  of  England.  227  Illustrations.  753  pages. 

Cloth,  $3.00;  Leather,  $3.50 
From  the  Archives  of  Gyntecology,  New  York. 

"  The  illustrations  are  mostly  NEW  and  WELL  EXECUTED,  and  we  heartily  commend  this  book  as  far  superior  to  any  manual 

YEO'S^MANUAL  OF  PHYSIOLOGY.  Fourth  Edition.  A  New  Text-book  for  Students.  By 
GERALD  F.  YEO,  M.D.,  F.R.C.S.,  Professor  of  Physiology  in  King's  College,  London.  321  Illustra- 
tions and  a  Glossary.  758  pages.  Cloth,  $3.00;  Leather,  53-5° 

RICHTER'S  ORGANIC  CHEMISTRY.  By  PROF.  VICTOR  VON  RICHTER,  University  of  Breslau. 
Authorized  translation.  First  American,  from  the  Fourth  German  Edition.  By  EDGAR  F.  SMITH,  M.D., 
PH.D  ,  Translator  of  Richter's  Inorganic  Chemistry ;  Prof,  of  Chemistry  in  Wittenberg  College,  Spring- 
field, Ohio;  formerly  in  the  Laboratories  of  the  University  of  Pennsylvania;  Member  of  the  Chemical 
Societies  of  Berlin  and  Paris,  of  the  Academy  of  Natural  Sciences  of  Philadelphia,  etc.  Illustrated. 
710  pages.  Cloth,  $300;  Leather.  $3.50 

GOODHARTAND  STARR,  DISEASES  OF  CHILDREN.  Second  Edition.  By  J.  F.GOOL-HART, 
M.D.,  Physician  to  the  Evelina  Hospital  for  Children;  Assistant  Physician  to  Guy's  Hospital,  London. 
Second  American  from  third  English  Edition.  Revised  and  Edited  by  Louis  STARR,  M.D.,  Clinical 
Professor  of  Diseases  of  Children  in  the  Hospital  of  the  University  of  Pennsylvania,  and  Physician  to  the 
Children's  Hospital,  Phila.  With  many  new  Prescriptions  and  Directions  for  making  Artificial  Human 
Milk,  for  the  Artificial  Digestion  of  Milk,  etc.  760  pages.  Cloth,  $3.00;  Leather,  $3.50 

From  The  New  York  Medical  Record. 

"As  it  is  said  of  some   men,  to  it  might  be  said  ot  some  books,  that  they  are  'born  to  greatness.'     This  new  volume  has 

we  believe,  a  mission,  particularly  in  the  hands  of  the  young  members  of  the  profession.     In  these  days  of  prolixity  in  medical 

literature,  it  is  refreshing  to  meet  with  an  author  who  knows  both  what  to  say  and  when  he  has  said  it." 

WARING'S  PRACTICAL  THERAPEUTICS.  Fourth  Edition.  A  Manual  of  Practical  Thera- 
peutics, considered  with  reference  to  Articles  of  the  Materia  Medica.  Containing,  also,  an  Index  of 
Diseases,  with  a  list  of  Medicines  applicable  as  Remedies,  and  a  full  Index  of  the  Medicines  and 
Preparations  noticed  in  the  work.  By  EDWARD  JOHN  WARING,  M.D.,  F.R.C.P.,  F.L.S.,  etc.  4th 
Edition.  Rewritten  and  Revised.  Edited  by  DUDLEY  W.  BUXTON.  M.D.,  Asst.  to  the  Prof,  of  Medicine 
at  University  College  Hospital;  Member  of  the  Royal  College  of  Physicians  of  London.  666  pages. 

Cloth,  $3.00;  Leather,  $3.50 

From  The  Kansas  Citv  Medical  Record. 

''As  a  work  of  reference  it  excels,  on  account  of  the  several  complete  indexes  added  to  this  edition.     It  was  deservedly 

popular  in  former  editions,  and  will  be  more  so  in  the  one  before  us,  on  account  of  the  careful  arrangement  of  the  subjects." 

REESE'S  MEDICAL  JURISPRUDENCE  AND  TOXICOLOGY.  Second  Edition.  By  JOHN  J. 
REESE,  M.D.,  Professor  of  Medical  Jurisprudence  and  Toxicology  in  the  University  of  Pennsylvania ;  late 
President  of  the  Medical  Jurisprudence  Society  of  Philadelphia;  Physician  to  St.  Joseph's  Hospital; 
Member  of  the  College  of  Physicians  of  Phila.;  Corresponding  Membtr  of  the  New  York  Medico- Legal 
Society,  etc.  2d  Edition.  Revised  and  Enlarged.  654  pages.  Cloih,  $300;  Leather,  #3.50 

THE  MOST  PRACTICAL  SERIES  OF  TEXT-BOOKS. 


JUST  PUBLISHED.     THIRD  EDITION. 

HUMAN  PHYSIOLOGY. 

BY  LANDOIS  AND  STIRLING. 

With  692  Illustrations. 

THIRD   AMERICAN,  FROM    THE   SIXTH    GERMAN    EDITION. 

A  Text-Book  of  Human  Physiology,  including  Histology  and  Microscopical  Anatomy, 
with  special  reference  to  the  requirements  of  Practical  Medicine.  •  By 
Dr.  L.  LANDOIS,  Professor  of  Physiology  and  Director  of  the  Physiological  Institute, 
University  of  Greifswald.     Translated^  from  the  Fifth  German  Edition,  with  addi- 
tions  by  WM.  STIRLING,  M.D.,  SC.D.,  Brackenbury,  Professor  of    Physiology  and 
Histology  in  Owen's  College  and  Victoria  University,  Manchester;    Examiner  in 
the  Honors'  School  ofScience,  University  of  Oxford,  England.      Third  Edition, 
revised  and  enlarged.     692  Illustrations. 
"A   BRIDGE    BETWEEN    PHYSIOLOGY   AND    PRACTICAL    MEDICINE." 

One  Volume.    Eoyal  Octavo.    Cloth,  $6.50 ;  leather,  $7.50. 

From  the  Prefaces  to  the  English  Edition. 

The  fact  that  Prof.  Landois'  book  has  passed  through  four  large  editions  in  the  original  since  1880,  and 
that  in  barely  six  months'  time  a  second  edition  of  the  English  has  been  called  for,  shows  that  in  some 
special  way  it  has  met  a  want.  The  characteristic  which  has  thus  commended  the  work  will  be  found 
mainly  to  lie  in  its  eminent  practicability;  and  it  is  this  consideration  which  has  induced  me  to  undertake  the 
task  of  putting  it  into  English.  Landois'  work,  in  fact,  forms  a  Bridge  between  Physiology  and  the  Practice 
of  Medicine.  It  never  loses  sight  of  the  fact  that  the  student  of  to-day  is  the  practicing  physician  of 
to-morrow.  In  the  same  way,  the  work  offers  to  the  busy  physician  in  practice  a  ready  means  of  refreshing 
his  memory  on  the  theoretical  aspects  of  Medicine.  He  can  pass  backward  from  the  examination  of  patho- 
logical phenomena  to  the  normal  processes,  and,  in  the  study  of  these,  find  new  indications  and  new  lights 
for  the  appreciation  and  treatment  of  the  cases  under  consideration.  With  this  object  in  view,  all  the 
methods  of  investigation  which  may,  to  advantage,  be  used  by  the  practitioner,  are  carefully  and  fully 
described.  Many  additions,  and  about  one  hundred  illustrations,  have  been  introduced  into  this  second 
English  edition,  and  the  whole  work  carefully  revised. 

PRESS  NOTICES. 

"  Most  effectively  aids  the  busy  physician  to  trace  from  morbid  phenomena  back  the  course  of  divergence  from 
healthy  physical  operations,  and  to  gather  in  this  way  new  lights  and  novel  indications  for  the  COMPREHENSION  AND  TREATMENT 
of  the  maladies  with  which  he  is  called  upon  to  cope." — American  Journal  of  Medical  Sciences. 

"  I  know  of  no  book  which  is  its  equal  in  the  applications  to  the  needs  of  clinical  medicine." — Prof.  Harrison  Allen,  late 
Professor  of  Physiology,  University  of  Pennsylvania. 

"  We  have  no  hesitation  in  saying  that  THIS  is  THE  WORK  to  which  the  PRACTITIONER  will  turn  whenever  he  desires  light 
thrown  upon  the  phenomena  of  a  COMPLICATED  OR  IMPORTANT  CASE." — Edinburgh  Medical  Journal. 

"  So  great  are  the  advantages  offered  by  Prof.  LANDOIS'  TEXT-BOOK,  from  the  EXHAUSTIVE  and  EMINENTLY  PRACTICAL 
manner  in  which  the  subject  is  treated,  that  it  has  passed  through  FOUR  large  editions  in  the  same  number  of  years.  .  .  . 
Dr.  STIRLING'S  annotations  have  materially  added  to  the  value  of  the  work.  Admirably  adapted  for  the  PRACTITIONER.  .  .  . 
With  this  Text-book  at  command,  NO  STUDENT  COULD  FAIL  IN  HIS  EXAMINATION." — The  Lancet. 

"One  of  the  MOST  PRACTICAL  WORKS  on  Physiology  ever  written,  forming  a  '  bridge  '  between  Physiology  and  Practical 
Medicine.  .  .  .  Its  chief  merits  are  its  completeness  and  conciseness.  .  .  .  The  additions  by  the  Editor  are  able  and  judicious. 
.  .  .  EXCELLENTLY  CLHAR,  ATTRACTIVE  and  SUCCINCT." — British  Medical  Journal. 

"  The  great  subjects  dealt  with  are  treated  in  an  admirably  clear,  terse,  and  happily  illustrated  manner." — Practitioner. 

"  Unquestionably  the  most  admirable  exposition  of  the  relations  of  Human  Physiology  to  Practical  Medicine  ever  laid 
before  English  readers  " — Stuaents'  Journal. 

"  As  a  work  of  reference,  LANDOIS  and  STIRLING'S  Treatise  OUGHT  TO  TAKE  THE  FOREMOST  PLACE  among  the  text- 
books in  the  English  language.  The  wood-cuts  are  noticeable  for  their  number  and  beauty." — Glasgow  Medical  Journal. 

"Landois'  Physiology  is,  without  question,  the  best  text-book  on  the  subject  that  has  ever  been  written." 
— New  York  Medical  Record. 

"  The  chapter  on  the  Brain  and  Spinal  Cord  will  be  a  rrost  valuable  one  for  the  general  reader,  the  translator's  notes  adding 
not  a  little  to  its  importance.  The  sections  on  Sight  and  Hearing  are  exhaustive.  .  .  .  The  Chemistry  of  the  Urine  is  thoroughly 
considered.  ...  In  its  present  form,  the  value  of  the  original  has  been  greatly  increased.  .  .  .  The  text  is  smooth,  accurate, 
and  unusually  fiee  from  Germanisms  ;  in  fact,  it  is  good  English." — New  York  Medical  Journal . 

"  It  is  not  for  the  physiological  student  alone  that  Prof.  Landois'  book  possesses  great  value,  for  IT  HAS  BEEN  ADDRESSED 
TO  THE  PRACTITIONER  OF  MEDICINE  as  well,  who  will  find  here  a  direct  application  of  physiological  to  pathological  processes." 
Medical  Bulletin. 

P.  BLAKISTON,  SON  &  CO.,  Publishers,  1012  Walnut  St.,  Philadelphia. 


DISEASES  OF  THE  SKIN, 

BY  T.  MCCALL  ANDERSON,  M.D., 

Professor  of  Clinical  Medicine  in  the  University  of  Glasgow. 
ASSISTED  BY 

DR.  JAMES  CHRISTIE,  Sec'y  London  Epidemiological  Society  for  Indian  Ocean  and  East  Africa;  Mem. 
Medical  Soc.  of  Bombay,  etc.  DR.  HECTOR  C.  CAMERON,  Surgeon  and  Lecturer  to  Western  Infirmary, 
Glasgow;  Surgeon  to  Glasgow  Hospital  for  Children,  etc.  WILLIAM  MACEWEN,  M.B.,  M.D.,  Lecturer  on 
Systematic  and  Clinical  Surgery,  Royal  Infirmary;  Surgeon  to  Royal  Infirmary  and  Children's  Hospital, 
Glasgow,  etc. 

WITH  COLORED  PLATES  AND  NUMEROUS  WOOD  ENGRAVINGS. 

Octavo.     650  Pages.     Cloth,  $4.50  ;  Leather,  $5.50. 

A  treatise  on  Diseases  of  the  Skin,  with  reference  to  Diagnosis  and  Treatment, 
including  an  Analysis  of  11,000  Consecutive  Cases.  Thoroughly  illustrated  by  new  and 
handsome  wood  engravings,  and  several  colored  and  steel  plates  prepared,  under  the 
direction  of  the  author,  from  special  drawings  by  Dr.  John  Wilson. 

PARTICULARLY  STRONG  IN  TREATMENT. 

8s&*  Special  attention  is  given  to  the  Differential  Diagnosis  of  Skin  Diseases  and  to  the 
treatment.  There  are  over  150  prescriptions,  which  will  serve  as  hints  to  the  physician 
in  dealing  with  obstinate  and  chronic  cases. 

There  has  been  no  complete  treatise  on  Dermatology  issued  for  several  years  ;  Professor 
Anderson  has,  therefore,  chosen  an  opportune  time  to  publish  his  book. 


ILLUSTRATING  ONE  OF  THE  DISEASES  OF  THE  HAIR  (See  fig. fy, page  7). 

For  nearly  twenty-five  years  Professor  Anderson  has  been  a  general  practitioner  and  a 
hospital  physician,  with  unusual  opportunities  for  the  study  of  this  class  of  diseases,  though 
not  a  "specialist,"  as  the  term  is  understood.  His  experience  is,  therefore,  of  great 
value,  and  the  physician  will  feel  that,  in  consulting  this  work,  he  is  reading  the  expe- 
riences of  a  man  situated  as  himself — with  the  same  difficulties  of  diagnosis  and  treatment, 
and  who  has  surmounted  them  successfully.  We  believe  this  to  be  a-  valuable  feature  of 
the  book  that  will  be  recognized  at  once;  for  it  is  undoubtedly  a  fact  that  a  work  like 
the  present  contains  much  practical  information  and  many  hints  not  to  be  found  else- 
where. Professor  Anderson  is  particularly  happy  in  illustrating  the  impor- 
tant relations  subsisting  between  the  general  economy  and  its  covering,  and 
his  ideas  of  pathology  and  therapeutics,  including  a  consideration  of  all  the  general 
and  local  manifestations  of  the  common  diseases  of  the  economy  which  are  manifested 
upon  the  surface,  will  find  many  appreciative  readers. 

Diseases  of  the  hair  receive  full  systematic  treatment. 

"  We  welcome  Dr.  Anderson's  work  not  only  as  a  friend,  but  as  a  benefactor  to  the  profession,  because  the  author  has 
stricken  off  mediaeval  shackles  of  insuperable  nomenclature  and  made  crooked  ways  straight  in  the  diagnosis  and  treatment  of 
this  hitherto  but  little  understood  class  of  diseases.  The  chapter  on  Eczema  is,  alone,  worth  the  price  of  the  book." — Nashville 
Medical  A  ews. 


NEW  AND 
REVISED 
EDITIONS 


}  PQU1Z-COMPENDS.P 


A  SERIES  OF  PRACTICAL  MANUALS  FOR  THE  PHYSICIAN  AND  STUDENT. 

Compiled  in  accordance  with  the  latest  teachings  of  prominent  lecturers 
and  the  most  popular  Text-books. 

Bound  in  Cloth,  each  $1.00.     Interleaved,  for  the  Addition  of  Notes,  $1.25. 

They  form  a  most  complete,  practical  and  exhaustive  set  of  manuals,  containing  information 
nowhere  else  collected  in  such  a  practical  shape.  Thoroughly  up  to  the  times  in  every  respect, 
containing  many  new  prescriptions  and  formulae,  and  over  300  illustrations,  many  of  which  have 
been  drawn  and  engraved  specially  for  this  series.  The  authors  have  had  large  experience  as 
quiz-masters  and  attaches  of  colleges,  with  exceptional  opportunities  for  noting  the  most  recent 
advances  and  methods.  The  arrangement  of  the  subjects,  illustrations,  types,  etc.,  are  all  of  the 
most  approved  form.  They  are  constantly  being  revised,  so  as  to  include  the  latest  and  best 
teachings,  and  can  be  used  by  students  of  any  college  of  medicine,  dentistry  and  pharmacy. 
No.  i.  Human  Anatomy.  Fifth  Edition,  including  Visceral  Anatomy,  formerly 

published  separately.      16  Lithograph  Plates,  Tables,  and  117  Illustrations.     By 

SAMUEL  O.  L.  POTTER,  M.A.,  M.D.,  late  A.  A.  Surgeon,  U.  S.  Army.    Professor  of  Practice, 

Cooper  Med.  College,  San  Francisco. 
Nos.  2  and  3.     Practice  of   Medicine.      Fourth   Edition,   Enlarged.      By  DANIEL   E. 

HUGHES,  M.D.,  late  Demonstrator  of  Clinical  Medicine  in  Jefferson  Med.  College,  Phila. ; 

Physician-in  Chief,  Philadelphia  Hospital.     In  two  parts. 

PART  I. — Continued,  Eruptive  and  Periodical  Fevers,  Diseases  of  the  Stomach,  Intestines,  Peritoneum, 
Biliary  Passages,  Liver,  Kidneys,  etc.  (including  Tests  for  Urine),  General  Diseases,  etc. 

PART  II.  —  Diseases  of  the  Respiratory  System  (including  Physical  Diagnosis),  Circulatory  System  and 
Nervous  System  ;  Diseases  of  the  Blood,  etc. 

*$*  These  little  books  can  be  regarded  as  a  full  set  of  notes  upon  the  Practice  of  Medicine,  containing  the 
Synonyms,  Definitions,  Causes,  Symptoms,  Prognosis,  Diagnosis,  Treatment,  etc.,  of  each  disease,  and  including 
a  number  of  prescriptions  hitherto  unpublished. 

No.  4.  Physiology,  including  Embryology.  Fifth  Edition.  By  ALBERT  P.  BRUBAKER, 
M.D.,  Prof,  of  Physiology,  Penn'a  College  of  Dental  Surgery;  Demonstrator  of  Physiology 
in  Jefferson  Med.  College,  Phila.  Revised,  Enlarged  and  Illustrated. 

No.  5.  Obstetrics.  Illustrated.  Fourth  Edition.  For  Physicians  and  Students.  By 
HENRY  G.  LANDIS,  M.D.,  Prof,  of  Obstetrics  and  Diseases  of  Women,  in  Starling  Medical 
College,  Columbus.  Revised  Edition.  New  Illustrations. 

No.  6.  Materia  Medica,  Therapeutics  and  Prescription  Writing.  Fifth  Revised 
Edition.  With  especial  Reference  to  the  Physiological  Action  of  Drues,  and  a  complete 
article  on  Prescription  Writing.  Based  on  the  Last  Revision  (Sixth)  of  the  U.  S.  Pharma- 
copoeia, and  including  many  unofficinal  remedies.  By  SAMUEL  O.  L.  POTTER,  M.A.,  M.D., 
late  A.  A.  Surg.  U.  S.  Army ;  Prof,  of  Practice,  Cooper  Med.  College,  San  Francisco.  5th 
Edition.  Improved  and  Enlarged. 

No.  7.  Gynaecology.  A  Compend  of  Diseases  of  Women.  By  HENRY  MORRIS,  M.D., 
Demonstrator  of  Obstetrics,  Jefferson  Medical  College,  Philadelphia.  Many  Illustrations. 

No.  8.  Diseases  of  the  Eye  and  Refraction,  including  Treatment  and  Surgery.  By  L. 
WEBSTER  Fox,  M.D.,  Chief  Clinical  Assistant  Opthalmological  Dept.,  Jefferson  Medical 
College,  etc.,  and  GEO.  M.  GOULD,  M  D.  71  Illustrations,  39  Formulae.  2d  Edition. 

No.  9.  Surgery,  Minor  Surgery  and  Bandaging.  Illustrated.  Fourth  Edition.  Includ- 
ing Fractures,  Wounds,  Dislocations,  Sprains,  Amputations  and  other  operations;  Inflam- 
mation, Suppuration,  Ulcers,  Syphilis,  Tumors,  Shock,  etc.  Diseases  of  the  Spine,  Ear, 
Bladder,  Testicles,  Anus,  and  other  Surgical  Diseases.  By  ORVILLE  HORWITZ,  A.M.,  M.D., 
Demonstrator  of  Surgery,  Jefferson  Medical  College.  84  Formulae  and  136  Illustrations. 

No.  10.  Medical  Chemistry.  Third  Edition.  Inorganic  and  Organic,  including  Urine 
Analysis.  For  Medical  and  Dental  Students.  By  HENRY  LF.FFMANN,  M.D.,  Prof,  of  Chem- 
istry in  Penn'a  College  of  Dental  Surgery,  Phila.  Third  Edition.  Revised  and  Enlarged. 

No.  II.  Pharmacy.  Based  upon  "Remington's  Text-Book  of  Pharmacy."  By  F.  E. 
STEWART,  M.D.,  PH.G.,  Professor  of  Pharmacy,  Powers  College  of  Pharmacy;  late  Quiz- 
Master  at  Philadelphia  College  of  Pharmacy.  Third  Edition.  Revised. 

No.  12.  Veterinary  Anatomy  and  Physiology.  Illustrated.  By  WM.  R.  BALLOU,  M.D., 
Prof,  of  Equine  Anatomy,  New  York  College  of  Veterinary  Surgeons,  etc.  29  Illustrations. 

No.  13.  Dental  Pathology  and  Dental  Medicine.  Containing  all  the  most  noteworthy 
points  of  interest  to  the  Dental  student.  By  GEO.  W.  WARREN,  D.D.S.,  Clinical  Chief, 
Penn'a  College  of  Dental  Surgery,  Philadelphia.  Illus. 

No.  14.  Diseases  of  Children.  By  MARCUS  P.  HATFIELD,  Professor  of  Diseases  of 
Children,  Chicago  Medical  College.  With  Colored  Plate. 

These  books  are  constantly  revised  to  keep  up  with  the  latest  teachings  and  discoveries. 


"IT  STANDS  WITHOUT  AN  EQUAL  AS  THE  MOST  COMPLETE  WORK  ON  PRACTICE  IN 
THE  ENGLISH  LANGUAGE."— New  York  Medical  Journal. 

FAGGE'S  PRACTICE  OF  MEDICINE, 

Two  Large  Royal  Octavo  Volumes.     Containing  over  1900  Pages. 
PRICE,  HANDSOMELY   BOUND  IN  CLOTH,  S8.OO. 

The  Principles  and  Practice  of  Medicine. 

BY  CHARLES  HILTON  FAGGE,  M.D.,  F.R.C.P.,  F.R.M.C.S., 

Examiner  in  Medicine,  University  of  London;  Physician  to,  and  Lecturer  on  Pathology  in,  Guy's  Hospital; 
Senior  Physician  to  Evelina  Hospital  for  Sick  Children,  etc. 

EDITED   AND   ARRANGED    FOR   THE   PRESS 

BY  P.  H.  PYE-SMITH,  M.D.,  F.R.C.P., 

Lecturer  on  Medicine  in  Guy's  Hospital,  London,  etc. , 

WITH  A  SECTION  ON  CUTANEOUS  AFFECTIONS,  BY  THE  EDITOR,  A  CHAPTER  ON  CAR- 
DIAC DISEASES,  BY  SAMUEL  WlLKES,  M.  D.,  F.  R.  S.,  AND  TWO  INDEXES,  ONE  OF 
AUTHORS  AND  ONE  OF  SUBJECTS,  BY  ROBERT  EDMUND  CARRINGTON. 

Two  Volumes.  Royal  Octavo.  1900  Pages. 

Price  in  Cloth,  $3.00.    Full  Leather,  $10.00.     Half  Morocco,  $12.00.    Half  Russia,  $12.00. 


It  is  based  on  laborious  researches  into  the  pathological  and  clinical  records  of 
Guy's  Hospital,  London,  during  the  twenty  years  in  which  the  author  has  held  office 
there  as  Medical  Registrar,  as  Pathologist,  and  as  Physician.  Familiar  beyond  most, 
if  not  all,  of  his  contemporaries,  with  modern  medical  literature,  a  diligen'.  reader  of 
French  and  German  periodicals,  Dr.  Fagge,  with  his  remarkably  retentive  memory  and 
methodical  habits,  was  able  to  bring  to  his  work  of  collection  and  criticism  almost 
unequaled  opportunities  of  extensive  experience  in  the  wards  and  dead  house.  The 
result  is  that  which  will  probably  be  admitted  to  be  a  fuller,  more  original,  and  more 
elaborate  text-book  on  medicine  than  has  yet  appeared.  It  is  the  first  of  importance 
emanating  from  Guy's  Hospital,  and  the  only  two-volume  work  on  the  Practice  of 
Medicine  that  has  been  issued  for  a  number  of  years.  Several  subjects,  such  as 
Syphilis,  that  are  usually  omitted  or  but  slightly  spoken  of  in  a  general  work  of  this 
character,  receive  full  attention. 

Dr.  Walter  Moxon,  one  of  Dr.  Fagge's  contemporaries,  and  a  great  personal 
friend,  writes  of  him,  in  a  recent  number  of  the  London  Lancet : — 

"  Fagge  was,  to  my  mind,  the  type  of  true  medical  greatness.  I  believe  he  was  capable  of  any  kind  of 
excellence.  His  greatness  as  a  physician  became  evident  to  observers  of  character  very  soon  after  his  brilliant 
student  career  had  placed  him  on  the  staff  of  Guy's  Hospital;  he  did  not  merely  group  already  known  facts, 
but  he  found  new  facts.  Former  volumes  of  Guy's  Hospital  Reports  contain  ample  and  most  valuable  proof  of 
his  greatness  as  a  physician.  '  His  power  of  observation  was  sustained  by  immense  memory,  and  brought  into 
action  by  vivid  and  constant  suggestiveness  of  intelligence.  He  was  a  physician  by  grace  of  nature,  and  being 
gifted  with  a  quickness  of  perception,  a  genius  for  clinical  facts  and  a  patience  in  observation,  he  was  at  once 
recognized  as  a  successful  practitioner  and  a  leading  figure  in  the  hospital  and  among  the  profession. 


NEW  TEXT-BOOKS. 


Macalister's  Human  Anatomy.     816  Illustrations  (400  of 
which  are  Original).     Just  Ready. 

A  NEW  TEXT  BOOK  for  Students  and  Practitioners,  Systematic  and  Topographical, 
including  the  Embryology,  Histology  and  Morphology  of  Man.  With  special 
reference  to  the  requirements  of  Practical  Surgery  and  Medicine. 
By  ALEX.  MACALISTER,  M.D.,  F.R.S.,  F.S.A.,  Professor  of  Anatomy  in  the  Univer- 
sity of  Cambridge,  England;  Examiner  in  Zoology  and  Comparative  Anatomy, 
University  of  London  ;  formerly  Professor  of  Anatomy  and  Surgery,  University 
of  Dublin.  With  816  Illustrations,  400  of  which  are  original.  Octavo. 

Cloth,  $7.50;  Leather,  $8.50 

>  ***  Professor  Macalister's  reputation  as  an  Anatomist  and  Zoologist  is  such  that 
nothing  need  be  said  of  the  scientific  value  of  this  book.  Regarding  the  illustrations, 
printing  and  binding  we  may  say,  however,  that  the  workmanship  is  of  the  best 
character  in  every  respect.  No  expense  has  been  spared  to  make  a  handsome  vol- 
ume, the  400  original  illustrations  adding  greatly  to  its  appearance  as  well  as  to  its 
practical  value  as  a  working  book  for  students  and  physicians. 

Potter's  Materia  Medica,  Pharmacy  and  Therapeutics. 
Second  Edition.     Revised  and  Enlarged. 

A   HANDBOOK   OF   MATERIA   MEDICA,  PHARMACY  AND  THERAPEUTICS — including 

the  Physiological  Action  of  Drugs,  Special  Therapeutics  of  Diseases,  Official  and 
Extemporaneous  Pharmacy,  etc.  By  SAM'L  O.  L.  POTTER,  M.A.,  M.D.,  Professor 
of  the  Practice  of  Medicine  in  Cooper  Medical  College,  San  Francisco;  Late 
A.  A.  Surgeon,  U.  S.  Army,  Author  of  "Speech  and  its  Defects,"  and  the  "Quiz- 
Compends"  of  Anatomy  and  Materia  Medica,  etc.  Revised,  Enlarged  and  Im- 
oroved.  Octavo.  With  Thumb  Index  in  each  copy. 

Cloth,  $4.00;  Leather,  $5.00 

"  The  author  has  aimed  to  embrace  ia  a  single  volume  the  essentials  of  practical  materia 
medica  and  therapeutics,  and  has  produced  a  book  small  enough  for  easy  carriage  and  easy  ref- 
erence, large  enough  to  contain  a  carefully  digested,  but  full,  clear  and  well-arranged  mass  of 
information.  He  has  not  adhered  to  any  pharmacopoeia,  as  is  the  case  of  certain  recent  manuals, 
thereby  limiting  his  woik,  and  in  this  day  of  new  remedies  causing  c  nstant  disappointment,  but 
has  brought  it  up  to  date  in  the  most  satisfactory  way.  No  new  remedy  of  any  acknowledged 
value  is  omitted  from  this  list.  Under  each  the  section  on  physiological  action  and  therapeutics 
has  been  written  with  care.  ...  In  the  enumeration  of  drugs  suited  to  different  disorders  a 
very  successful  efiort  at  discrimination  has  been  made,  both  in  the  stage  of  disease  and  in  the 
cases  peculiarly  suited  to  the  remedy.  It  is  no  mere  list  of  diseases  followed  by  a  catalogue 
of  drugs,  but  is  a  digest  of  modern  therapeutics,  and  as  such  will  prove  of  immense  use  to  its 
possessor." — The  Therapeutic  Gazette. 

Winckel's  Obstetrics.     Original  Illustrations. 

A  TEXT-BOOK   OF   OBSTETRICS,  INCLUDING  THE  PATHOLOGY   AND  THERAPEUTICS 

OF  THE  PUERPERAL  STATE.  By  DR.  F.  WiNCKEL,  Professor  of  Gynaecology, 
and  Director  of  the  Royal  University  Clinic  for  Women,  in  Munich.  Authorized 
Translation,  by  J.  CLIFTON  EDGAR,  M.D.,  Adjunct  Professor  to  the  Chair  of 
Obstetrics,  Medical  Dept.,  University,  of  the  City  of  New  York,  with  nearly  200 
handsome  illustrations,  the  majority  of  which  are  original  with  this  work.  Octavo. 

Cloth,  $6.00;  Leather,  #7.00 


PUBLISHED  ANNUALLY. 


1891. 


NOW  READY.     40™  YEAR. 


T HE  PHYSICIAN'S  VISITING  ]JST. 


(LINDSAY  &  BLAKISTON'S.) 

CONTENTS. 


ALMANAC  for  1890  and  1891. 

TABLE  OF  SIGNS  to  be  used  in  keeping  accounts. 

MARSHALL  HALL'S  READY  METHOD  IN  ASPHYXIA. 

POISONS  AND  ANTIDOTES,  revised  for  1890. 

THE  METRIC  OR  FRENCH  DECIMAL  STSTBM  OF 
WEIGHTS  AND  MEASURES. 

DOSE  TABLE,  revised  and  rewritten  for  1890,  by  Hc- 
BART  AMORY  HARE,  M.D,  Demonstrator  of  Thera- 
peutics, University  of  Pennsylvania. 

LIST  OF  NEW  REMEDIES  for  1890,  by  same  author. 

AIDS  TO  DIAGNOSIS  AND  TREATMENT  OF  DISEASES  OF 
THE  EYE,  DR.  L.  WEBSTER  Fox,  Clinical  Asst.  Eye 
Dept.,  Jefferson  Medical  College  Hospital,  and  G. 
M.  GOULD,  M.D. 

DIAGRAM  SHOWING  ERUPTION  OF  MILK  TEETH,  DR. 
Louis  STARR,  Prof,  of  Diseases  of  Children,  Univer- 
sity Hospital,  Philadelphia. 


POSOLOGICAL  TABLE,  MEADOWS. 

DISINFECTANTS  AND  DISINFECTING. 

EXAMINATION  OF  URINE,  DR.  J.  D ALAND,  based  up<n 
Tyson's  "  Practical  Examination  of  Urine."  6tn 
Edition. 

INCOMPATIBILITY,  DR.  S.  O.  L.  POTTER. 

A  NEW  COMPLETE  TABLE  FOR  CALCULATING  THE 
PERIOD  OF  UTERO-GESTATION. 

SYLVESTER'S  METHOD  FOR  ARTIFICIAL  RESPIRATION. 
Illustrated. 

DIAGRAM  OF  THE  CHEST. 

BLANK  LEAVES,  suitably  ruled,  for  Visiting  Lists, 
Monthly  Memoranda,  Addresses  of  Patients  and 
others ;  Addresses  of  Nurses,  their  references,  etc. ; 
Accounts  asked  for;  Memoranda  of  Wants  ;  Obstet- 
ric and  Vaccination  Engagements  ;  Record  of  Births 
and  Deaths  ;  Cash  Account,  etc. 


REGULAR   EDITION. 


For  25  Patients  weekly. 
50 

75        " 

TOO 

50     " 

IOO  "  " 


For  25  Patients  weekly. 
50 

50        «' 


2  Vols. 
2  Vols. 


Jan.  to  June 
July  to  Dec. 
Jan.  to  June 
July  to  Dec. 


Tucks,  pockets  and  Pencil,  $1.00 

1.25 
1.50 

2.00 
"  "  "  2.50 

3.00 


INTERLEAVED  EDITION. 

Interleaved,  tucks  and  Pencil, 

2  Vols     !  Jan'  to  June  I 
2  vois.    |julyto  Dec  j 


1.25 
1.50 

3-00 


PERPETUAL  EDITION,  without  Dates. 
No.  1.     Containing  space  for  over  1300  names,  with  blank  page  opposite  each 

Visiting  List  page.     Bound  in  Red  Leather  cover,  with  pocket  and  Pencil, 
No.  2.     Containing  space  for  2600  names,  with  blank  page  opposite  each 

Visiting  List  page.     Bound  like  No.  I,  with  Pocket  and  Pencil,     .... 


Sl.23 

1.50 

MONTHLY  EDITION,  without  Dates. 

No.  1.     Bound  without  Flap  or  Pencil, 75 

No.  2,        "      with  Tucks,  Pencil,  etc., i.oc 

These  lists,  without  dates,  can  be  commenced  at  any  time,  and  used  until  full, 
and  are  particularly  useful  to  young  physicians  unable  to  estimate  the  number  of 
patients  they  may  have  during  the  first  years  of  Practice,  and  to  physicians  in  locali- 
ties where  epidemics  occur  frequently.  In  the  Monthly  Edition  the  patient's  name 
has  to  be  entered  but  once  each  month. 

"  For  completeness,  compactness,  and  simplicity  of  arrangement  it  is  excelled  by  none  in  the  market." — ff.  Tf 
Medical  Record. 

' '  The  book  is  convenient  in  form,  not  too  bulky,  and  in  every  respect  the  very  best  Visiting  List  published.' 
—  Canada  Medical  and  Surgical  Journal. 

"  After  all  the  trials  made,  there  are  none  superior  to  it." — Gaillard's  Medical  Journal. 

"  The  most  popular  Visiting  List  extant."— Buffalo  Medical  and  Surgical  Journal. 

"  We  have  used  it  for  years,  and  do  not  hesitate  to  pronounce  it  equal,  if  not  superior,  to  any."— Soutkeri 
Clinic. 

This  is  not  a  complicated  system  of  keeping  accounts,  but  a  plain,  systematic 
record  which,  with  the  least  expenditure  of  time  and  trouble,  keeps  an  accurate  and 
concise  list  of  daily  visits,  engagements,  etc. 


